Lincoln Electric LF-72 Base Model, Bench Model Standard Duty, Bench Model Heavy Duty, LF-74 Wire Feeder Service Manual
Below you will find brief information for Wire Feeder LF-72 Base Model, Wire Feeder LF-72 Bench Model Standard Duty, Wire Feeder LF-72 Bench Model Heavy Duty. The LF-72 wire feeder models are designed for use with Lincoln Electric welding power sources. The wire feeders offer a variety of features, including a wide range of wire feed speeds, adjustable pressure arms, and compatibility with a variety of welding guns and torches. These models are suitable for a variety of welding applications, including MIG, TIG, and flux-cored welding.
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LF-72/74
For use with machines having Code Number : 11075 thru 11293
SVM171-A
January, 2007
Safety Depends on You
Lincoln arc welding and cutting equipment is designed and built with safety in mind. However, your overall safety can be increased by proper installation
. . . and thoughtful operation on your part.
DO NOT INSTALL,
OPERATE OR REPAIR THIS
EQUIPMENT WITHOUT READ-
ING THIS MANUAL AND THE
SAFETY PRECAUTIONS CON-
TAINED THROUGHOUT. And, most importantly, think before you act and be careful.
SERVICE MANUAL
Copyright © 200
7 Lincoln Global Inc.
• World's Leader in Welding and Cutting Products •
• Sales and Service through Subsidiaries and Distributors Worldwide •
Cleveland, Ohio 44117-1199 U.S.A. TEL: 1-888-935-3877 FAX: 216.486.1751 WEB SITE: www.lincolnelectric.com
i
SAFETY
WARNING
CALIFORNIA PROPOSITION 65 WARNINGS
Diesel engine exhaust and some of its constituents are known to the State of California to cause cancer, birth defects, and other reproductive harm.
The Above For Diesel Engines
The engine exhaust from this product contains chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm.
The Above For Gasoline Engines
i
ARC WELDING CAN BE HAZARDOUS. PROTECT YOURSELF AND OTHERS FROM POSSIBLE SERIOUS INJURY OR DEATH.
KEEP CHILDREN AWAY. PACEMAKER WEARERS SHOULD CONSULT WITH THEIR DOCTOR BEFORE OPERATING.
Read and understand the following safety highlights. For additional safety information, it is strongly recommended that you purchase a copy of “Safety in Welding & Cutting - ANSI Standard Z49.1” from the American Welding Society, P.O. Box 351040,
Miami, Florida 33135 or CSA Standard W117.2-1974. A Free copy of “Arc Welding Safety” booklet E205 is available from the
Lincoln Electric Company, 22801 St. Clair Avenue, Cleveland, Ohio 44117-1199.
BE SURE THAT ALL INSTALLATION, OPERATION, MAINTENANCE AND REPAIR PROCEDURES ARE
PERFORMED ONLY BY QUALIFIED INDIVIDUALS.
FOR ENGINE powered equipment.
1.a. Turn the engine off before troubleshooting and maintenance work unless the maintenance work requires it to be running.
____________________________________________________
1.b. Operate engines in open, well-ventilated areas or vent the engine exhaust fumes outdoors.
1.h. To avoid scalding, do not remove the radiator pressure cap when the engine is hot.
ELECTRIC AND
MAGNETIC FIELDS may be dangerous
____________________________________________________
1.c. Do not add the fuel near an open flame welding arc or when the engine is running. Stop the engine and allow it to cool before refueling to prevent spilled fuel from vaporizing on contact with hot engine parts and igniting. Do not spill fuel when filling tank. If fuel is spilled, wipe it up and do not start engine until fumes have been eliminated.
____________________________________________________
1.d. Keep all equipment safety guards, covers and devices in position and in good repair.Keep hands, hair, clothing and tools away from V-belts, gears, fans and all other moving parts when starting, operating or repairing equipment.
____________________________________________________
1.e. In some cases it may be necessary to remove safety guards to perform required maintenance. Remove guards only when necessary and replace them when the maintenance requiring their removal is complete.
Always use the greatest care when working near moving parts.
___________________________________________________
1.f. Do not put your hands near the engine fan.
Do not attempt to override the governor or idler by pushing on the throttle control rods while the engine is running.
2.a. Electric current flowing through any conductor causes localized Electric and Magnetic Fields (EMF). Welding current creates EMF fields around welding cables and welding machines
2.b. EMF fields may interfere with some pacemakers, and welders having a pacemaker should consult their physician before welding.
2.c. Exposure to EMF fields in welding may have other health effects which are now not known.
2.d. All welders should use the following procedures in order to minimize exposure to EMF fields from the welding circuit:
2.d.1. Route the electrode and work cables together - Secure them with tape when possible.
2.d.2. Never coil the electrode lead around your body.
2.d.3. Do not place your body between the electrode and work cables. If the electrode cable is on your right side, the work cable should also be on your right side.
___________________________________________________
1.g. To prevent accidentally starting gasoline engines while turning the engine or welding generator during maintenance work, disconnect the spark plug wires, distributor cap or magneto wire as appropriate.
2.d.4. Connect the work cable to the workpiece as close as possible to the area being welded.
2.d.5. Do not work next to welding power source.
Mar ‘95
ii
ELECTRIC SHOCK can kill.
3.a. The electrode and work (or ground) circuits are electrically “hot” when the welder is on.
Do not touch these “hot” parts with your bare skin or wet clothing. Wear dry, hole-free gloves to insulate hands.
3.b. Insulate yourself from work and ground using dry insulation.
Make certain the insulation is large enough to cover your full area of physical contact with work and ground.
In addition to the normal safety precautions, if welding must be performed under electrically hazardous conditions (in damp locations or while wearing wet clothing; on metal structures such as floors, gratings or scaffolds; when in cramped positions such as sitting, kneeling or lying, if there is a high risk of unavoidable or accidental contact with the workpiece or ground) use the following equipment:
• Semiautomatic DC Constant Voltage (Wire) Welder.
• DC Manual (Stick) Welder.
• AC Welder with Reduced Voltage Control.
3.c. In semiautomatic or automatic wire welding, the electrode, electrode reel, welding head, nozzle or semiautomatic welding gun are also electrically “hot”.
3.d. Always be sure the work cable makes a good electrical connection with the metal being welded. The connection should be as close as possible to the area being welded.
3.e. Ground the work or metal to be welded to a good electrical
(earth) ground.
3.f. Maintain the electrode holder, work clamp, welding cable and welding machine in good, safe operating condition. Replace damaged insulation.
3.g. Never dip the electrode in water for cooling.
3.h. Never simultaneously touch electrically “hot” parts of electrode holders connected to two welders because voltage between the two can be the total of the open circuit voltage of both welders.
3.i.
When working above floor level, use a safety belt to protect yourself from a fall should you get a shock.
3.j.
Also see Items 6.c. and 8.
SAFETY
ARC RAYS can burn.
4.a. Use a shield with the proper filter and cover plates to protect your eyes from sparks and the rays of the arc when welding or observing open arc welding. Headshield and filter lens should conform to ANSI Z87. I standards.
4.b. Use suitable clothing made from durable flame-resistant material to protect your skin and that of your helpers from the arc rays.
4.c. Protect other nearby personnel with suitable, non-flammable screening and/or warn them not to watch the arc nor expose themselves to the arc rays or to hot spatter or metal.
FUMES AND GASES can be dangerous.
5.a. Welding may produce fumes and gases hazardous to health. Avoid breathing these fumes and gases.When welding, keep your head out of the fume. Use enough ventilation and/or exhaust at the arc to keep fumes and gases away from the breathing zone.
When welding with electrodes which require special ventilation such as stainless or hard facing (see instructions on container or MSDS) or on lead or cadmium plated steel and other metals or coatings which produce highly toxic fumes, keep exposure as low as possible and below Threshold Limit Values (TLV) using local exhaust or mechanical ventilation. In confined spaces or in some circumstances, outdoors, a respirator may be required. Additional precautions are also required when welding on galvanized steel.
5. b. The operation of welding fume control equipment is affected by various factors including proper use and positioning of the equipment, maintenance of the equipment and the specific welding procedure and application involved. Worker exposure level should be checked upon installation and periodically thereafter to be certain it is within applicable OSHA PEL and ACGIH TLV limits.
5.c. Do not weld in locations near chlorinated hydrocarbon vapors coming from degreasing, cleaning or spraying operations.
The heat and rays of the arc can react with solvent vapors to form phosgene, a highly toxic gas, and other irritating products.
5.d. Shielding gases used for arc welding can displace air and cause injury or death. Always use enough ventilation, especially in confined areas, to insure breathing air is safe.
5.e. Read and understand the manufacturer’s instructions for this equipment and the consumables to be used, including the material safety data sheet (MSDS) and follow your employer’s safety practices. MSDS forms are available from your welding distributor or from the manufacturer.
5.f. Also see item 1.b.
AUG 06
ii
iii
WELDING SPARKS can cause fire or explosion.
6.a. Remove fire hazards from the welding area.
If this is not possible, cover them to prevent the welding sparks from starting a fire.
Remember that welding sparks and hot materials from welding can easily go through small cracks and openings to adjacent areas. Avoid welding near hydraulic lines. Have a fire extinguisher readily available.
6.b. Where compressed gases are to be used at the job site, special precautions should be used to prevent hazardous situations. Refer to “Safety in Welding and Cutting” (ANSI
Standard Z49.1) and the operating information for the equipment being used.
6.c. When not welding, make certain no part of the electrode circuit is touching the work or ground. Accidental contact can cause overheating and create a fire hazard.
6.d. Do not heat, cut or weld tanks, drums or containers until the proper steps have been taken to insure that such procedures will not cause flammable or toxic vapors from substances inside. They can cause an explosion even though they have been “cleaned”. For information, purchase “Recommended
Safe Practices for the Preparation for Welding and Cutting of
Containers and Piping That Have Held Hazardous
Substances”, AWS F4.1 from the American Welding Society
(see address above).
6.e. Vent hollow castings or containers before heating, cutting or welding. They may explode.
6.f. Sparks and spatter are thrown from the welding arc. Wear oil free protective garments such as leather gloves, heavy shirt, cuffless trousers, high shoes and a cap over your hair. Wear ear plugs when welding out of position or in confined places.
Always wear safety glasses with side shields when in a welding area.
6.g. Connect the work cable to the work as close to the welding area as practical. Work cables connected to the building framework or other locations away from the welding area increase the possibility of the welding current passing through lifting chains, crane cables or other alternate circuits.
This can create fire hazards or overheat lifting chains or cables until they fail.
6.h. Also see item 1.c.
SAFETY
CYLINDER may explode if damaged.
7.a. Use only compressed gas cylinders containing the correct shielding gas for the process used and properly operating regulators designed for the gas and pressure used. All hoses, fittings, etc. should be suitable for the application and maintained in good condition.
7.b. Always keep cylinders in an upright position securely chained to an undercarriage or fixed support.
7.c. Cylinders should be located:
• Away from areas where they may be struck or subjected to physical damage.
• A safe distance from arc welding or cutting operations and any other source of heat, sparks, or flame.
7.d. Never allow the electrode, electrode holder or any other electrically “hot” parts to touch a cylinder.
7.e. Keep your head and face away from the cylinder valve outlet when opening the cylinder valve.
7.f. Valve protection caps should always be in place and hand tight except when the cylinder is in use or connected for use.
7.g. Read and follow the instructions on compressed gas cylinders, associated equipment, and CGA publication P-l,
“Precautions for Safe Handling of Compressed Gases in
Cylinders,” available from the Compressed Gas Association
1235 Jefferson Davis Highway, Arlington, VA 22202.
iii
FOR ELECTRICALLY powered equipment.
8.a. Turn off input power using the disconnect switch at the fuse box before working on the equipment.
8.b. Install equipment in accordance with the U.S. National
Electrical Code, all local codes and the manufacturer’s recommendations.
8.c. Ground the equipment in accordance with the U.S. National
Electrical Code and the manufacturer’s recommendations.
Mar ‘95
iv
PRÉCAUTIONS DE SÛRETÉ
SAFETY
zones où l’on pique le laitier.
Pour votre propre protection lire et observer toutes les instructions et les précautions de sûreté specifiques qui parraissent dans ce manuel aussi bien que les précautions de sûreté générales suivantes:
iv
6. Eloigner les matériaux inflammables ou les recouvrir afin de prévenir tout risque d’incendie dû aux étincelles.
7. Quand on ne soude pas, poser la pince à une endroit isolé de la masse. Un court-circuit accidental peut provoquer un
échauffement et un risque d’incendie.
Sûreté Pour Soudage A L’Arc
1. Protegez-vous contre la secousse électrique: a. Les circuits à l’électrode et à la piéce sont sous tension quand la machine à souder est en marche. Eviter toujours tout contact entre les parties sous tension et la peau nue ou les vétements mouillés. Porter des gants secs et sans trous pour isoler les mains.
b. Faire trés attention de bien s’isoler de la masse quand on soude dans des endroits humides, ou sur un plancher metallique ou des grilles metalliques, principalement dans les positions assis ou couché pour lesquelles une grande partie du corps peut être en contact avec la masse.
c. Maintenir le porte-électrode, la pince de masse, le câble de soudage et la machine à souder en bon et sûr état defonctionnement.
d.Ne jamais plonger le porte-électrode dans l’eau pour le refroidir.
e. Ne jamais toucher simultanément les parties sous tension des porte-électrodes connectés à deux machines à souder parce que la tension entre les deux pinces peut être le total de la tension à vide des deux machines.
f. Si on utilise la machine à souder comme une source de courant pour soudage semi-automatique, ces precautions pour le porte-électrode s’applicuent aussi au pistolet de soudage.
8. S’assurer que la masse est connectée le plus prés possible de la zone de travail qu’il est pratique de le faire. Si on place la masse sur la charpente de la construction ou d’autres endroits
éloignés de la zone de travail, on augmente le risque de voir passer le courant de soudage par les chaines de levage, câbles de grue, ou autres circuits. Cela peut provoquer des risques d’incendie ou d’echauffement des chaines et des câbles jusqu’à ce qu’ils se rompent.
9. Assurer une ventilation suffisante dans la zone de soudage.
Ceci est particuliérement important pour le soudage de tôles galvanisées plombées, ou cadmiées ou tout autre métal qui produit des fumeés toxiques.
10. Ne pas souder en présence de vapeurs de chlore provenant d’opérations de dégraissage, nettoyage ou pistolage. La chaleur ou les rayons de l’arc peuvent réagir avec les vapeurs du solvant pour produire du phosgéne (gas fortement toxique) ou autres produits irritants.
11. Pour obtenir de plus amples renseignements sur la sûreté, voir le code “Code for safety in welding and cutting” CSA Standard
W 117.2-1974.
2. Dans le cas de travail au dessus du niveau du sol, se protéger contre les chutes dans le cas ou on recoit un choc. Ne jamais enrouler le câble-électrode autour de n’importe quelle partie du corps.
3. Un coup d’arc peut être plus sévère qu’un coup de soliel, donc:
PRÉCAUTIONS DE SÛRETÉ POUR
LES MACHINES À SOUDER À
TRANSFORMATEUR ET À
REDRESSEUR
a. Utiliser un bon masque avec un verre filtrant approprié ainsi qu’un verre blanc afin de se protéger les yeux du rayonnement de l’arc et des projections quand on soude ou quand on regarde l’arc.
b. Porter des vêtements convenables afin de protéger la peau de soudeur et des aides contre le rayonnement de l‘arc.
c. Protéger l’autre personnel travaillant à proximité au soudage à l’aide d’écrans appropriés et non-inflammables.
4. Des gouttes de laitier en fusion sont émises de l’arc de soudage. Se protéger avec des vêtements de protection libres de l’huile, tels que les gants en cuir, chemise épaisse, pantalons sans revers, et chaussures montantes.
1. Relier à la terre le chassis du poste conformement au code de l’électricité et aux recommendations du fabricant. Le dispositif de montage ou la piece à souder doit être branché à une bonne mise à la terre.
2. Autant que possible, I’installation et l’entretien du poste seront effectués par un électricien qualifié.
3. Avant de faires des travaux à l’interieur de poste, la debrancher à l’interrupteur à la boite de fusibles.
4. Garder tous les couvercles et dispositifs de sûreté à leur place.
5. Toujours porter des lunettes de sécurité dans la zone de soudage. Utiliser des lunettes avec écrans lateraux dans les
Mar. ‘93
v
RETURN TO MAIN MENU
MASTER TABLE OF CONTENTS FOR ALL SECTIONS
Parts Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .P501 Series (LF-72)
P518 Series (LF-74) v
LF-72/74
Section A-1
TABLE OF CONTENTS
- INSTALLATION SECTION -
Section A-1
Installation ..............................................................................................................Section A
Base Model, Bench Model Standard Duty and Bench Model Heavy Duty...............A-18
LF-72/74 SINGLE/DUAL
A-2
INSTALLATION
TECHNICAL SPECIFICATIONS: LF-72 Wire Feeder
A-2
SPEC.# TYPE WIRE FEED SPEED RANGE
Wire Size
LF-72 Speed Solid Cored
K2327-1
Base Model
K2327-4
K2327-2 Bench Model 50-800 IPM
(1.27-20.3 m/m) Standard Duty
K2327-3 Bench Mode
Heavy Duty
.023 - 1/16 in.
.035 - 5/64 in
(0.6 - 1.6 mm) (0.9 - 2.0 mm)
CONTROL BOX, WIRE DRIVE AND COMPLETE UNITS
SPEC.# TYPE INPUT POWER PHYSICAL SIZE• TEMPERATURE RATING
Input Voltage Dimensions and Current Height Width Depth Operating Storage
K2327-1 LF-72 11.1“
( 282 mm)
10.2“ 12.9“
(259 mm) (328 mm)
Weight
43 Lbs
(19.7 Kg.)
K2327-4 Base Model 26.5 Lbs
(12.0 Kg)
Height
Dimensions
∆
Width Depth Weight
LF-72
K2327-2 24-42VAC
9 AMPS
12.6“
( 320 mm)
10.9“
(277 mm)
22.5“ 52.5 Lbs 14°F to 104°F -40°F to 85°F
(572 mm) (23.8 Kg.) (-10°C to 40°C) (-40°C to 85°C) Bench
Standard
Duty
Height
Dimensions
∆
Width Depth Weight
LF-72
K2327-3 15.3“
( 389 mm)
13.0“ 27.7“ 67.5 Lbs
(330 mm) (704 mm) (30.6 Kg.) Bench
Heavy
Duty
WELDING CAPACITY RATING
Amp Rating Duty Cycle
500 A
400 A
60%
100%
∆ Dimensions do not include wire reel.
LF-72/74
A-3
INSTALLATION
MOUNTING
SAFETY PRECAUTION
ELECTRIC SHOCK can kill.
• Only qualified personnel should perform this installation.
A-3
For location and size,
LF-72 Bench Model Rear
Mounting Holes (See Figure A.1) and for Bottom
Mounting Holes (See Figure A.2).
• Turn off the input power to the power source at the disconnect switch or fuse box before working on this equipment. Turn off the input power to any other equipment connected to the welding system at the disconnect switch or fuse box before working on this equipment.
FIGURE A.1
• Do not touch electrically hot parts.
----------------------------------------------------------------------------------------
LOCATION
The LF-72 may be placed on a bench or mounted on top of a welding power source.
Place the LF-72 in a clean and dry location.
Do not stack the LF-72.
FIGURE A.2
LF-72/74
A-4
BENCH MOUNT
INSTALLATION
BOOM MOUNT
The LF-72 mounts in a variety of configurations. As shipped from the factory, the LF-72 is suitable for bench mounting or placing directly on top of the welding power source (CV-xxx and DC-xxx product family only).
Bench Mount
A-4
When boom mounting, remove the wire reel stand (if assembled) and secure the wire feeder directly to the desired surface.
SWIVEL MOUNT
Both the standard duty bench model and heavy duty bench model may be mounted onto a swivel when a top a welding power source.
Swivel Kit and Bench Model, Standard Duty
SUSPENDED
Only suspend the wire feeder by the lift bail of the portability kit.
Swivel Kit and Base Model LF-72
WARNING
Alternative methods for hanging the wire feeder must not be used unless insulation is provided between the wire feeder enclosure and the hanging device.
------------------------------------------------------------------------
LF-72/74
A-5
INSTALLATION
SAFETY PRECAUTION
ELECTRIC SHOCK can kill.
• Only qualified personnel should perform this installation.
• Turn off the input power to the power source at the disconnect switch or fuse box before working on this equipment. Turn off the input power to any other equipment connected to the welding system at the disconnect switch or fuse box before working on this equipment.
• Do not touch electrically hot parts.
----------------------------------------------------------------------
WELD CABLE SIZES
Table A.1 has the copper cable sizes recommended for different currents and duty cycles. Lengths stipulated are the distance from the welder to work and back to the welder again. Cable sizes are increased for greater lengths primarily for the purpose of minimizing voltage in the welding circuit.
TABLE A.1
RECOMMENDED CABLE SIZES (RUBBER COVERED COPPER - RATED 75°C)**
A-5
Amperes
200
200
225
225
250
Percent
Duty
Cycle
CABLE SIZES FOR COMBINED LENGTHS OF ELECTRODE AND WORK CABLES
0 to 50 Ft.
50 to 100Ft.
100 to 150 Ft.
150 to 200 Ft.
200 to 250 Ft.
0 to 15 m 15 to 31 m
31 to 48 m 48 to 61 m
61 to 76 m
60
100
20
40 & 30
30
2
2
4 or 5
3
3
2
2
3
3
3
2
2
2
2
2
1
1
1
1
1
250
250
250
300
40
60
100
60
1
1
2
1
1
1
2
1
1
1
1
1
1
1
1
1/0
1/0
1/0
1/0
2/0
325
350
400
400
500
100
60
60
100
60
2/0
1/0
2/0
3/0
2/0
2/0
1/0
2/0
3/0
2/0
2/0
2/0
2/0
3/0
3/0
2/0
2/0
3/0
3/0
3/0
3/0
3/0
4/0
4/0
4/0
** Tabled values are for operation at ambient temperatures of 40°C and below. Applications above 40°C may require cables larger than recommended, or cables rated higher than 75°C.
1/0
1/0
1/0
1/0
1/0
LF-72/74
A-6
COAXIAL WELD CABLES
INSTALLATION
Coaxial welding cables are specially designed welding cables for pulse welding or STT welding. Coaxial weld cables feature low inductance, allowing fast changes in the weld current. Regular cables have a higher inductance which may distort the pulse or STT wave shape.
Inductance becomes more severe as the weld cables become longer.
A-6
A coaxial weld cable is constructed by 8 small leads wrapped around one large lead. The large inner lead connects to the electrode stud on the power source and the electrode connection on the wire feeder. The small leads combine together to form the work lead, one end attached to the power source and the other end to the work piece. (See Coaxial weld Cable below.)
Coaxial weld cables are recommended for all pulse and STT welding, especially when the total weld cable length (electrode cable + work cable) exceeds 50 feet
(7.6m)
WELD CABLE CONNECTION
Connect a work lead of sufficient size between the proper output stud on the power source and the work.
Be sure the connection to the work makes tight metal to metal electrical contact. Poor work lead connections can result in poor welding performance.
Work
Electrode
Work
Power Source
Work
Electrode
Coaxial Weld Cable
Wire Feeder
Electrode
Work
LF-72/74
A-7
INSTALLATION
ANALOG CONTROL CABLE
CONTROL CABLE CONNECTIONS
• All control cables can be connected end to end to extend their length.
The control cable connecting the wire feeder to the power source is specially made for the welding environment.
The wire feeder power requires overcurrent protection.
Connect the wire feeder only to power sources with overcurrent protection of no more than 15 amps.
POWER SOURCE
J
I
H
G
N
F
K
A
B
M
L
E
D
C
WIRE FEEDER
B
A
C
L
D
E
K
J
I
M
N
G
H
F
PIN
A
B
C
D
E
F
G
H
J
I
FUNCTION LEAD#
Unused
Reserved
Welding Output Control
(trigger from feeder)
Welding Output Control
(trigger from feeder)
Remote Voltage Control
(“+” supply from feeder or remote)
Remote Voltage Control
(control signal from feeder or remote)
Remote Voltage Control
(“-” supply from feeder or remote)
42 VAC
Reserved
Reserve for Future Use.
-------
-------
2
4
77
76
75
41
K
L
42 VAC
Reserve for Future Use.
42
M
N
Unused
Electrode voltage from feeder
-------
67
Do not use more than 100 ft (30.5 m) of control cable between the wire feeder and power source.
LF-72/74
A-7
A-8
NOTES
ANALOG MILLER CONTROL CABLE
ADAPTER K2335-1
This Lincoln Electric wire feeder may be mounted to a limited number of Miller Electric power sources. The Miller power source must have the amphenol pin definition shown in the table below for proper operation of the wire feeder.
Operation of Lincoln wire feeders on Miller power sources may result in lack of high speeds or reduce pull force on high wire feed speeds. Maximum wire feed speed for the LF-72 operating on a Miller power source is approximately 720ipm.
Be sure the Miller power source provides 24 VAC to the wire feeder and has overcurrent protection of no more than 15 amps. The power source must not exceed 113VDC peak.
POWER SOURCE
H
I
J
N
G
F
A
K
B
M
L
D
C
E
WIRE FEEDER
C
B
A
L
D
E
J
K
I
N
M
F
G
H
MILLER POWER SOURCE LINCOLN WIRE FEEDER
Pin Function Pin Function
A
B
C
D
E
24 VAC to feeder
Welding Output Control
+10VDC to feeder for remote control
Remote control common
0-10VDC from feeder for remote control.
I
D
C
E
G
F
42 VAC feeder
Welding Output Control
Welding Output Control
Remote Voltage Control ("+" supply, from power source)
Remote Voltage Control ("-" supply, from power source)
Remote Voltage Control (control signal from feeder or remote.)
Reserved for future use.
F
G
H
Current feedback to feeder.
Scaled 0-10V. 1 V = 100 amps.
Referenced to pin D.
24 VAC common.
Arc Voltage feedback to feeder.
Scaled 0-10V. 1 V = 10 Arc volts.
Referenced to pin D.
K
L
J
42 VAC to feeder
Reserved for future use.
I
J
K
L
M
N N Electrode voltage to power source (67)
Miller is a registered trademark not owned or licensed by The Lincoln Electric Company.
LF-72/74
A-8
A-9
INSTALLATION
WELDING GUN/WIRE FEEDER TRIGGER
CONNECTOR
A-9
REMOTE SENSE LEAD SPECIFICATIONS
Wire Feeder
Amphenol
Welding G un
Refer to the power source instruction manual for instructions for connecting the wire feeder for STT welding.
A
E
D
B
C
Trigger Lead
WIRE DRIVE SYSTEMS
Drive Roll Kits are designed to feed specific types and wire sizes. The LF-72 Bench Model comes with the combo KP1696-1. All other Drive Roll Kits listed are not included, but are available for ordering from the following tables:
Wire Feeder
Pin
A
B
C
D
E
-
-
-
Function
Gun Trigger
Common
Drive Roll Kits, Steel Wires
Includes: 2 Smooth V groove drive rolls and an inner wire guide.
HIGH FREQUENCY PROTECTION
Locate the LF-72 away from radio controlled machinery. The normal operation of the LF-72 may adversely affect the operation of RF controlled equipment, which may result in bodily injury or damage to the equipment
KP1696-030S
KP1696-035S
KP1696-045S
KP1696-052S
KP1696-1/16S
KP1696-1
KP1696-2
.023-.030 (0.6-0.8mm)
.035 (0.9mm)
.045 (1.2mm)
.052 (1.4mm)
1/16 (1.6mm)
.035, .O45 (0.9, 1.2mm)
.040 (1.0mm)
Drive Roll Kits, Cored Wires
Includes: 2 Knurled drive rolls and an inner wire guide.
KP1697-035C
KP1697-045C
KP1697-052C
KP1697-1/16C
KP1697-068
KP1697-5/64C
.030-.035" (0.8-0.9mm)
.040-.045" (1.0-1.2mm)
.052" (1.4mm)
1/16" (1.6mm)
.068-.072" (1.7-1.8mm)
5/64" (2.0mm)
Drive Roll Kits, Aluminum Wire
Includes: 2 polished U groove drive rolls, outer wire guide and an inner wire guide.
KP1695-035A
KP1695-040A
KP1695-3/64A
KP1695-1/16A
.035" (0.9 mm)
.040" (1.0mm)
3/64" (1.2mm)
1/16" (1.6mm)
DRIVE ROLLS
INNER WIRE
GUIDE
LF-72/74
A-10
INSTALLATION
WELDING GUNS, TORCHES AND ACCES-
SORIES
A-10
3. Fully insert the gun cable connector end into the gun receiver bushing and gently tighten the thumb screw as show in Figure A.3 below.
GUN RECEIVER BUSHING
The LF-72 wire feeder comes with a K1500-2 gun receiver bushing.
4. Connect the gun trigger connector to the trigger receptacle. Make sure that the key ways are aligned and insert.
MAGNUM GUN AND CABLE ASSEMBLIES
The LF-72 wire feeder model will accept a number of optional gun and cable assemblies. An example of installing the Gun and Cable is shown in Figure A.3
with a 15 ft. (4.6m) long Magnum 400 gun and cable.
1. Turn off power at the welding power source.
2. Unscrew Thumb screw on Wire Drive Unit, until tip of screw no longer protrudes into gun bushing hole as seen from the front of machine.
FIGURE A.3
LF-72 BASE MODEL
TRIGGER RECEPTACLE
GUN AND CABLE
GUN HANDLE
GUN TUBE
GUN NOZZLE
GUN RECEIVER BUSHING
(INTERCHANGABLE)
WIRE DRIVE UNIT
GUN TRIGGER
CONNECTOR
CABLE CONNECTOR
END K466-10
LF-72/74
A-11
INSTALLATION
PROCEDURE FOR CHANGING
DRIVE AND IDLE ROLL SETS
(See Figure A.4 )
WARNING
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the welding power source before installation or changing drive rolls and/or guides.
• Do not touch electrically live parts.
• When inching with the gun trigger, electrode and drive mechanism are "hot" to work and ground and could remain energized several seconds after the gun trigger is released.
• Only qualified personnel should perform maintenance work.
-----------------------------------------------------------------------
-
1. Turn power off at the welding power source.
2. Release the idle roll pressure arm.
3. Remove the outer wire guide by turning the knurled thumbscrews counter-clockwise to unscrew them from the feed plate.
4. Rotate the triangular lock and remove the drive
1. Turn power off at the welding power source.
2. Remove the welding wire from the wire drive.
3. Remove the thumb screw from the wire drive.
4. Remove the welding gun from the wire drive.
A-11
WIRE DRIVE CONFIGURATION
(See Figure A.5)
Changing the Gun Receiver Bushing
WARNING
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the disconnect switch or fuse box before attempting to connect or disconnect input power lines, output cables or control cables.
• Only qualified personnel should perform this installation.
------------------------------------------------------------------------
Tools required:
• 1/4" hex key wrench
Note: Some gun bushings do not require the use of the thumb screw.
5. Loosen the socket head cap screw that holds the connector bar against the gun bushing. Important:
Do not attempt to completely remove the socket head cap screw.
6. Remove the outer wire guide, and push the gun bushing out of the wire drive. Because of the precision fit, light tapping may be required to remove the gun bushing.
rolls.
FIGURE A.4
5. Remove the inner wire guide.
6. Insert the new inner wire guide, groove side out, over the two locating pins in the feed plate.
7. Install a drive roll on each hub assembly secure with the triangular lock.
8. Install the outer wire guide by aligning it with the pins and tightening the knurled thumbscrews.
9. Close the idle arm and engage the idle roll pressure arm. Adjust the pressure appropriately.
GUN RECEIVER BUSHING
FIGURE A.5
THUMB SCREW
OUTER WIRE GUIDE
CONNECTOR BLOCK
SOCKET HEAD
CAP SCREW
LOOSEN TIGHTEN
LF-72/74
A-12
INSTALLATION
7. Disconnect the shielding gas hose from the gun bushing, if required.
PRESSURE ARM ADJUSTMENT
WARNING
8. Connect the shielding gas hose to the new gun bushing, if required.
ELECTRIC SHOCK can kill.
9. Rotate the gun bushing until the thumb screw hole aligns with the thumb screw hole in the feed plate.
Slide the gun receiver bushing into the wire drive and verify the thumb screw holes are aligned.
10. Tighten the socket head cap screw.
11. Insert the welding gun into the gun bushing and tighten the thumb screw.
Gun Receiver
Bushing
For use With
K1500-1 K466-1 Lincoln gun connectors;
Innershield and Subarc guns)
A-12
• Turn the input power OFF at the welding power source before installation or changing drive rolls and/or guides.
• Do not touch electrically live parts.
• When inching with the gun trigger, electrode and drive mechanism are "hot" to work and ground and could remain energized several seconds after the gun trigger is released.
• Only qualified personnel should perform maintenance work.
------------------------------------------------------------------------
The pressure arm controls the amount of force the drive rolls exert on the wire. Proper adjustment of the pressure arm gives the best welding performance.
K1500-2 K466-2, K466-10 Lincoln gun connectors; Magnum 200/300/400 guns and compatible with Tweco®
#4)
Set the pressure arm as follows (See Figure A.6):
Aluminum wires between 1 and 3
Cored wires between 3 and 4
Steel, Stainless wires between 4 and 6
K1500-3 K1637-7 Lincoln gun connectors;
Magnum 550 guns and compatible with Tweco® #5)
FIGURE A.6
K1500-4
K1500-5
K489-7
K466-3 Lincoln gun connectors; compatible with Miller® guns.)
(Compatible with Oxo® guns.)
( Lincoln Fast-Mate guns.)
CORED WIRES
OUTERSHIELD
METALSHIELD
INNERS HIELD
1
3
5
2
4
6
SOLID WIRES
ALUMINUM
STEEL
STAINLE SS
LF-72/74
A-13
WIRE REEL LOADING
WARNING
INSTALLATION
A-13
3. Re-install the retaining collar. Make sure that the release bar snaps out and that the retaining collar fully engages the groove on the spindle.
FIGURE A.8
• Keep hands, hair, clothing and tools away from rotating equipment.
• Do not wear gloves when threading wire or changing wire spool.
• Only qualified personnel should install, use or service this equipment.
-----------------------------------------------------------------------
Retaining
Collar
Loading 10 to 15 lb. (4.5 – 6.8kg) Spools
A K468 spindle adapter is required for loading 2" wide spools on 2" (51mm) spindles. Use a K468-1 spindle adapter for loading 2-1/2" (64mm) wide spools. (See figure A.7 and figure A.8)
1. Squeeze the release bar on the retaining collar and remove it from the spindle.
2. Place the spindle adapter on the spindle, aligning the spindle brake pin with the hole in the adapter.
3. Place the spool on the spindle and align the adapter brake tab with one of the holes in the back side of the spool. An indicator mark on the end of the spindle shows the orientation of the brake tab. Be certain the wire feeds off of the spool in the proper direction.
4. Re-install the retaining collar. Make sure that the release bar snaps out and that the retaining collar fully engages the groove on the spindle.
FIGURE A.7
Adapter
Spindle Placement
The wire reel stand provides two mounting locations for the spindle. Each mounting location consists of a tube in the center of the mast and locating slots.
Loading 16 to 44 lb. (7.3 – 20kg) Spools
(See figure A.8)
1. Squeeze the release bar on the retaining collar and remove it from the spindle.
2. Place the spool on the spindle, aligning the spindle brake pin with one of the holes in the back side of the spool. An indicator mark on the end of the spindle shows the orientation of the brake holding pin.
Be certain the wire feeds off of the spool in the proper direction.
Loading 30 lb. (13.6 kg) Readi-Reels
A K363-P Readi-Reel adapter is required for loading these spools on 2" (51mm) spindles.
1. Squeeze the release bar on the retaining collar and remove it from the spindle.
2. Place the Readi-Reel adapter on the spindle, aligning the spindle brake pin with one of the holes in the adapter.
3. Re-install the retaining collar. Make sure that the release bar snaps out and that the retaining collar fully engages the groove on the spindle.
4. Rotate the spindle and adapter until the retaining spring is at the 12 o’clock position.
5. Position the Readi-Reel so that electrode de-reels in the proper direction.
6. Set one of the Readi-Reel inside cage wires on the slot in the retaining spring.
7. Lower the Read-Reel to depress the retaining spring and align the other inside cage wires with the grooves in the adapter.
8. Slide the cage all way onto the adapter until the retaining spring "pops up" fully.
Removing a Readi-Reel
1. To remove a Readi-Reel from the an adapter, depress the retaining spring with a thumb while pulling the Readi-Reel cage from the adapter with both hands. Do not remove the adapter from the spindle.
LF-72/74
A-14
INSTALLATION
FIGURE A.9
A-14
WELD WIRE ROUTING
The electrode supply may be either from reels, Readi-
Reels, spools, or bulk packaged drums or reels.
Observe the following precautions: a) The electrode must be routed to the wire drive unit so that the bends in the wire are at a minimum, and also that the force required to pull the wire from the reel into the wire drive unit is kept at a minimum.
b) The electrode is “hot” when the gun trigger is pressed and must be insulated from the boom and structure.
c) If more than one wire feed unit shares the same boom and are not sharing the some power source output stud, their wire and reels must be insulated from each other as well as insulated from their mounting structure.
LF-72/74
A-15
SHIELDING GAS CONNECTION
INSTALLATION
CYLINDER may explode if damaged.
A-15
5. Attach one end of the inlet hose to the outlet fitting of the flow regulator. Attach the other end to the welding system shielding gas inlet. Tighten the union nuts with a wrench.
• Keep cylinder upright and chained to support.
• Keep cylinder away from areas where it may be damaged.
• Never lift welder with cylinder attached.
• Never allow welding electrode to touch cylinder.
• Keep cylinder away from welding or other live electrical circuits.
------------------------------------------------------------------------
BUILD-UP OF SHIELDING GAS may harm health or kill.
6. Before opening the cylinder valve, turn the regulator adjusting knob counterclockwise until the adjusting spring pressure is released.
7. Standing to one side, open the cylinder valve slowly a fraction of a turn. When the cylinder pressure gage stops moving, open the valve fully.
8. The flow regulator is adjustable. Adjust it to the flow rate recommended for the procedure and process being used before making a weld.
• Shut off shielding gas supply when not in use.
SEE AMERICAN NATIONAL STANDARD Z-49.1,
"SAFETY IN WELDING AND CUTTING" PUB-
LISHED BY THE AMERICAN WELDING SOCIETY.
------------------------------------------------------------------------
Maximum inlet pressure is 100 psi. (6.9 bar.)
Install the shielding gas supply as follows:
1. Secure the cylinder to prevent it from falling.
2. Remove the cylinder cap. Inspect the cylinder valves and regulator for damaged threads, dirt, dust, oil or grease. Remove dust and dirt with a clean cloth.
DO NOT ATTACH THE REGULATOR IF OIL,
GREASE OR DAMAGE IS PRESENT! Inform your gas supplier of this condition. Oil or grease in the presence of high pressure oxygen is explosive.
3. Stand to one side away from the outlet and open the cylinder valve for an instant. This blows away any dust or dirt which may have accumulated in the valve outlet.
4. Attach the flow regulator to the cylinder valve and tighten the union nut(s) securely with a wrench.
Note: if connecting to 100% CO
2 cylinder, insert regulator adapter between regulator and cylinder valve.
If adapter is equipped with a plastic washer, be sure it is seated for connection to the CO
2 cylinder.
LF-72/74
A-16
INSTALLING ELECTRODE
CONDUIT KITS
WARNING
INSTALLATION
(For Codes 11209, 11210, 11211 and above)
To install Lincoln conduit: (See Figure A.10b)
A-16
1. Turn off power at the welding power source.
2. Remove the “O” ring holding the ball bushing assembly to the back of the wire feeder. Remove the ball bushing assembly.
FIGURE A.10b
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the disconnect switch before working on this equipment.
• Do not touch electrically hot parts.
------------------------------------------------------------------------
Electrode conduit is used when feeding wire drums, from boxes or large reels. For best feeding results, use the shortest conduit length possible and avoid sharp bends.
(For Codes 11075, 11076, 11077)
Tools required: (See Figure A.10a)
• Snap Ring Pliers
To install Lincoln conduit:
1. Turn off power at the welding power source.
2. Remove the snap ring holding the ball bushing assembly to the back of the wire feeder. Remove the ball bushing assembly.
FIGURE A.10a
"O" RING
3. Place a K1546-xx conduit connector into the back of the wire drive. Rotate the conduit connector to a position where the thumb screw does not interfere with the idle arm or door.
4. Tighten the set screw to secure the conduit connector in the wire drive.
5. Insert conduit through the sheet metal of the LF-72 and into the conduit connector.
Secure with the thumb screw.
FIGURE A.11
LF-72/74
A-17
WARNING
INSTALLATION
ALUMINUM WIRE PREPARATIONS
FIGURE A.12a
(For Codes 11209, 11210, 11211 and above)
Tools required: (See Figure A.12b)
• 9/64" Hex key wrench
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the disconnect switch before working on this equipment.
• Do not touch electrically hot parts.
1. Turn off power at the welding power source.
A-17
2. Remove the snap ring holding the ball bushing assembly to the back of the wire feeder. Remove the ball bushing assembly.
------------------------------------------------------------------------
Welding with aluminum filler wires requires extra care.
Aluminum wire is softer and not as stiff as steel wires, it is important to keep aluminum wire free of dirt and scratches. Limit gun length to 10 Ft.(3.0 m) for best results and use a spool cover if feeding from a spool.
"O" RING
To prevent scratching of the aluminum wire, remove the ball bearings from the ball housing as follows.
(For Codes 11075, 11076, 11077)
Tools required: (See Figure A.12a)
• Snap Ring Pliers
• 9/64" Hex key wrench
FIGURE A.12b
1. Turn off power at the welding power source.
2. Remove the snap ring holding the ball bushing assembly to the back of the wire feeder. Remove the ball bushing assembly.
3. Remove the three socket head cap screws from the ball bushing assembly.
Caution: as the screws are being loosened, the balls may fall free from the
assembly. Remove the balls and the steel washer.
FIGURE A.13
4. Place the ball bushing housing into the wire feeder case and secure with the snap ring or “O” ring depending on which code your machine uses.
LF-72/74
A-18
INSTALLATION
BASE MODEL
A-18
BENCH MODEL STANDARD DUTY
BENCH MODEL HEAVY DUTY
LF-72/74
A-19
INSTALLATION
TYPICAL SYSTEM CONFIGURATIONS
A-19
The LF-72 is capable of welding with many different welding processes. These processes may require reconfiguring the LF-72 with other products that may or may not be included with the model you purchased. Use the Table
1 below to identify the basic items which are included in the LF-72 to utilize the various Welding Processes that the machine is capable of controlling.
PART NO.
Description
Wire
Feeder
K2327-1 Base Model
Gun
TABLE 1
Wire Reel Stand
---
Drive Roll Kit CONTROL
CABLE
K2327-2 Bench Model,
Standard Duty
K2327-3 Bench Model,
Heavy Duty
LF-72
15', Magnum 400,
.035-.045 (0.9-1.2 mm)
Standard duty, up to
44 lb. (20 kg)spools.
Heavy Duty, up to
60 lb. (27.2 kg) coils.
.035-.045 combo
(0.9-1.2 mm) 10’ (3m)
K2327-4 Base Model
-------
LF-72/74
A-20
NOTES
A-20
LF-72/74
Section B-1
TABLE OF CONTENTS
- OPERATION SECTION -
Section B-1
Operation ................................................................................................................Section B
Recommended Processes and Required Equipment ..................................................B-3
LF-72/74 SINGLE/DUAL
B-2
WARNING
OPERATION
SAFETY PRECAUTIONS
Read this entire section of operating instructions before operating the machine.
B-2
The serviceability of a product or structure utilizing the LF-72 wire feeder is and must be the sole responsibility of the builder/user. Many variables beyond the control of The Lincoln Electric Company affect the results obtained in using the LF-72 wire feeder.
These variables include, but are not limited to, welding procedure, plate chemistry and temperature, weldment design, fabrication methods and service requirements. The available range of the LF-72 wire feeder may not be suitable for all applications, and the builder/user is and must be solely responsible for welding settings.
ELECTRIC SHOCK can kill.
• Unless using cold feed feature, when feeding with the gun trigger, the electrode and drive mechanism are always electrically energized and could remain energized several seconds after welding ceases.
• Do not touch electrically live parts or electrodes with your skin or wet clothing.
• Insulate yourself from the work and ground.
• Always wear dry insulating gloves.
-------------------------------------------------------------
ONLY QUALIFIED PERSONS SHOULD INSTALL,
USE OR SERVICE THIS EQUIPMENT. READ AND
FOLLOW THE MANUFACTURER’S INSTRUC-
TIONS, EMPLOYER’S SAFETY PRACTICES AND
MATERIAL SAFETY DATA SHEETS (MSDS) FOR
CONSUMABLES.
-----------------------------------------------------------
READ THIS WARNING, PROTECT YOURSELF &
OTHERS.
GRAPHIC SYMBOLS THAT APPEAR ON
THIS MACHINE OR IN THIS MANUAL
COLD FEED
POSITIVE OUTPUT
NEGATIVE OUTPUT
PROTECTIVE
GROUND
FUMES AND GASES can be dangerous.
• Keep your head out of fumes.
• Use ventilation or exhaust at the arc, or both, to keep fumes and gases from your breathing zone and general area.
WARNING OR
CAUTION
DANGEROUS
VOLTAGE
SHOCK
HAZARD
WELDING SPARKS can cause fire or explosion.
• Do not weld near flammable material.
• Do not weld on containers which have held flammable material.
WELDING
FUMES
EXPLOSION
ARC RAYS can burn.
• Wear eye, ear, and body protection.
GAS INPUT
-----------------------------------------------------------
Observe additional guidelines detailed in the beginning of this manual.
WORK
CONNECTION
LF-72/74
B-3
OPERATION
PROCESS LIMITATIONS
COMMON WELDING ABBREVIATIONS
WFS
• Wire Feed Speed
CV
• Constant Voltage
GMAW (MIG)
• Gas Metal Arc Welding
FCAW (Cable Innershield or Outershield)
• Flux Core Arc Welding
B-3
• Rated for up to 1/16(1.6 mm) solid electrode and 5/64
(2.0 mm) cored electrode.
• The maximum WFS is 800 in/min (20.3 M/min).
• The LF-72 is not recommended for GMAW-Pulse
(synergic), GTAW, GTAW-Pulse, SAW, CAG, SMAW.
• Do not use push-pull equipment with the LF-72.
• For K2327-2 Bench model, std. duty: Maximum spool size = 44 lb. (20 kg); 12 inch (300mm) diameter; 4 inch (100mm)
• For K2327-3 Bench model, heavy duty: Maximum spool size = 60 lb. (27.2 kg)
REQUIRED EQUIPMENT
PRODUCT DESCRIPTION
General Physical Description
Lincoln’s LF-72 is designed for use with the CV and DC family of power sources. These include:
The LF-72 is optimized for .035 through .045 (0.9mm
through 1.2mm) GMAW welding. The powerful 2 roll drive, heavy duty enclosure and wire reel stand combine to make an easy to install, easy to use wire feeder for everyday welding. Powering the wire drive is a high performance motor gearbox. A heavy duty hinged door opens easily, which provides an ample amount of room for assembling precision drive components and the welding gun. Also under the door is a convenient storage tray for contact tips and tools.
• CV-305
• CV-400
• CV-655
• DC-400
• DC-600
• Invertec™ V350
• Invertec™ V450
EQUIPMENT LIMITATIONS
Three packages are available. The basic unit consists of the wire drive box housing. The standard duty bench model targets users of 12" (305 mm)diameter spools.
The heavy duty bench model satisfies the needs of customers using 60 lb (27.2 kg) spools.
General Functional Description
• Maximum gun length =25 ft. (7.6m)
• Maximum conduit length = 30 ft. (9.1m)
• Maximum total control cable length = 100ft (31m)
• The LF-72 operates on 42VAC and not 115 VAC
• The K1733-1 wire straightener may not be used with the LF-72
• Gun bushings are required for welding guns that do not have a Magnum (Tweco #2-#4 compatible) back end.
• The LF-72 does not attach to K303 wire reel stands.
• The LF-72 is a highly versatile and economical choice of industrial feeders. Easy to use features are a calibrated WFS knob, cold-feed/ gas purge switch and trigger interlock.
• Several kits are available to expand the LF-72’s welding capability. The timer kit allows adjustment of burnback and postflow times. The remote voltage control kit includes a 0 to 10 dial for setting the welding voltage at the wire feeder. The swivel kit mounts to the lift bail of a power source and lets the feeder freely rotate so the gun cable stays straight.
RECOMMENDED PROCESSES
• GMAW .023-1/16 (0.6 - 1.6 mm) steel electrodes.
• FCAW .035 -5/64 (0.9 - 2.0mm) cored electrodes
LF-72/74
B-4
OPERATION
FRONT PANEL CONTROLS AND CONNECTIONS
FIGURE B.1 CASE FRONT CONTROLS
B-4
6
1
2
3
4
5
7
8
ITEM
3
4
1
2
7
8
5
6
DESCRIPTION
Location for
Optional Remote Voltage Control (See Accessory Section For Kit Number).
Location for
Optional Burnback and Postflow Timer Kit (See Accessory Section For Kit Number).
Thermal LED, Motor Overload.
Cold Feed - Gas Purge Switch, press the switch up to feed wire with weld output off.
Press the switch down for gas flow with weld output off.
2 step - Trigger Interlock switch.
Wire Feed Speed Knob.
Gun Receiver Bushing.
Trigger Connector 5-pin amphenol for connecting the MIG gun trigger. See Installation Section
for detail.
LF-72/74
B-5
OPERATION
1. REMOTE VOLTAGE CONTROL KIT
The
optional remote voltage control kit adjusts the arc voltage from the minimum to the maximum voltage of the welding power source. Rotate the knob counterclockwise to reduce the arc voltage and rotate the knob clockwise to raise the arc voltage.
B-5
3. THERMAL LED, MOTOR OVERLOAD
The thermal light illuminates when the wire drive motor draws too much current. If the thermal light illuminates, the wire drive will automatically shutdown for up to 30 seconds to allow the motor to cool. To start welding again, release the gun trigger, inspect the gun cable, liner (and conduit). Clean and make repairs as necessary. Start welding again when the problem has been safely resolved.
2. BURNBACK AND POSTFLOW TIMER KIT
The optional Burnback and Postflow Timer Kit gives control over the shielding gas at the end of the weld and prepares the end of the wire for the next arc start.
Additional shielding gas protection is often required when welding aluminum, stainless steel or exotic alloys.
For best results, keep the gun cable and conduit as straight as possible. Perform regular maintenance and cleaning on the gun liner, conduit and gun.
Always use quality electrode, such as L-50 or L-56 from Lincoln Electric.
4. COLD FEED/GAS PURGE SWITCH
Cold Feed and Gas Purge are combined into a single spring centered toggle switch.
To activate Cold Feeding, hold the switch in the UP position. The wire drive will feed electrode but neither the power source nor the gas solenoid will be energized. Adjust the speed of cold feeding by rotating the WFS knob. Cold feeding, or "cold inching" the electrode is useful for threading the electrode through the gun.
When stitch welding, set the postflow time to maximum for best results.
Burnback Timer
The burnback timer range is OFF to 0.25 seconds.
The burnback timer controls the additional amount of time the power source output remains ON after the wire drive has stopped feeding wire. Burnback adjustment prevents the wire from sticking to the weld at the end of a weld and helps to condition the wire for the next weld.
To set the burnback time, adjust the knob to approximately 0.03 seconds and then decrease or increase the time as desired.
Hold with toggle switch in the DOWN position to activate Gas Purge and let the shielding gas flow. The gas solenoid valve will energize but neither the power source output nor the drive motor will be turned on.
The Gas Purge switch is useful for setting the proper flow rate of shielding gas. Flow meters should always be adjusted while the shielding gas is flowing.
5. 2 STEP - TRIGGER INTERLOCK SWITCH
The 2 Step - Trigger Interlock switch changes the function of the gun trigger. 2
Step trigger operation turns welding on and off in direct response to the trigger.
Trigger Interlock operation allows welding to continue when the trigger is released for comfort on long welds.
Place the toggle switch in the DOWN position for 2
Step operation or in the UP position for Trigger
Interlock operation.
2 Step Trigger
Postflow Timer
The postflow timer range is OFF to 10 seconds.
Postflow is the time from when the power source output turns OFF until the postflow timer expires. Use postflow to protect the weld while the weld cools.
2 Step trigger operation is the most common. When the gun trigger is pulled, the welding power source energizes the electrode output and the wire feeder feeds wire for welding. The power source and wire feeder continue welding until the trigger is released.
LF-72/74 SINGLE/DUAL
B-6
Trigger Interlock
OPERATION
Trigger Interlock operation provides for operator comfort when making long welds. When the gun trigger is first pulled, the welding power source energizes the output and the wire feeder feeds wire for welding. The gun trigger is then released while the weld is made. To stop welding, the gun trigger is pulled again, and when it is released the welding power source output turns off and the wire feeder stops feeding wire.
CAUTION
• If the arc goes out while welding with trigger interlock operation, the electrode output from the welding power source remains energized and the wire feeder will continue to feed wire until the gun trigger is again pulled and then released.
------------------------------------------------------------------------
6. WIRE FEED SPEED KNOB
The large, calibrated wire feed speed knob makes for easy and accurate adjustment of the wire feed speed.
The knob rotates 3/4 turn. Turn the knob clockwise to increase the wire feed speed, and counter clockwise to reduce the wire feed speed.
The wire feed speed range is 50 to 800 in/min (1.27 -
20.3 m/min).
7. GUN RECEIVER BUSHING (K1500-2)
(K1500-2 bushing is standard on all LF-72's)
This Gun Receiver Bushing is used with Lincoln gun connectors, also with Magnum 200/300/400 guns and compatible with Tweco® #4).
8. TRIGGER CONNECTOR 5-PIN AMPHENOL
This is used for connecting the MIG gun trigger. See
Installation Section for detail.
B-6
LF-72/74
Section C-1
TABLE OF CONTENTS
- ACCESSORIES SECTION -
Section C-1
Accessories ............................................................................................................Section C
LF-72/74 SINGLE/DUAL
C-2
ACCESSORIES
OPTIONAL KITS:
K2329-1 Remote Voltage Control Kit.
Includes: 10k potentiometer, harness, knob and decal with a 0-10 scale and mounting hardware.
K2330-1 Timer Kit.
Includes: Panel and harness for adjusting burnback and postflow times.
K2328-1
K2331-1
K2332-1
K1796-xx
K1803-1
K1840-xx
K1841-xx
K1842-xx
Standard Duty Wire Reel Stand.
Includes: Wire Reel Stand for up to 44 lbs (20 kg) spools,
Spindle and mounting hardware.
Lift Bail Kit.
Includes: Insulated lift bail and hardware.
Swivel Kit.
(for use with Standard Duty Bench
Models)
Includes: Swivel adapter and mounting hardware for attaching to a power source lift bale.
Co-Axial Power Cable.
Work and Feeder Cables
Package.
Includes: Coaxial weld cable of length "xx". Ends of the weld cable have lug connections. Use for Pulse or STT welding.
Includes: Twist-Mate to Lug
2/0 cable 14' (1.2m) long with
Ground Clamp, and Twist-
Mate to Lug 2/0 Cable 9'
(2.7m) long.
Weld Power Cable, Twist-Mate to
Lug.
Includes: Twist-Mate to Lug,
1/0 cable of length "xx".
Weld Power Cable,
Twist-Mate to Twist-Mate.
Weld Power Cable, Lug to Lug.
Includes: Twist-Mate to Twist-
Mate, 1/0 Cable for 25' (7.6m) cables.
Includes: Twist-Mate to Twist-
Mate, 2/0 Cable for 50'
(15.2m) cables.
Includes: Lug to Lug, 3/0
Cable of length "xx" for lengths up to 60' (18.3m).
Lug to Lug, 4/0 Cable of length "xx" for lengths greater than 60' (18.3m).
LF-72/74
C-2
C-3
ACCESSORIES
OPTIONAL KITS:
K1797-xx
K2335-1
Control Cable.
Includes: 14 pin to 14 pin wire feeder to power source control cable.
Adapter for Miller Power Sources.
Includes: Adapter control cable for connecting a Lincoln
42 VAC wire feeder to a 24
VAC Miller power source.
K1520-1
K1798
K910-1
42 Volt Transformer Kit.
Adapter Cable for Control Cable to
Terminal Strip Power Sources.
Ground Clamp.
Includes: One transformer kit for operating a 42 VAC wire feeder on a power source supplying only 115 VAC.
Includes:
Includes: One 300 Amp
Ground Clamp.
K910-2 Ground Clamp.
Includes: One 500 Amp
Ground Clamp.
K1500-1
Gun Receiver Bushing (for guns with K466-1 Lincoln gun connectors; Innershield and Subarc guns.)
Includes: Gun receiver bushing, set screw and hex key wrench.
K1500-2
(standard on all
LF-72's)
Gun Receiver Bushing (for guns with
K466-2, K466-10 Lincoln gun connectors; Magnum 200/300/400 guns and compatible with Tweco® #4.)
Includes: Gun receiver bushing with hose nipple, set screw and hex key wrench.
K1500-3
Gun Receiver Bushing (for guns with K613-7 Lincoln gun connectors; Magnum 550 guns and compatible with Tweco® #5.)
Includes: Gun receiver bushing with hose nipple, set screw and hex key wrench.
K1500-4
K1500-5
Gun Receiver Bushing (for gun with K466-3 Lincoln gun connectors; compatible with Miller® guns.)
Includes: Gun receiver bushing with hose nipple, set screw and hex key wrench.
Gun Receiver Bushing (compatible with Oxo® guns.)
Includes: Gun receiver bushing with hose nipple, 4 guide tubes, set screw and hex key wrench.
C-3
LF-72/74
C-4
ACCESSORIES
OPTIONAL KITS:
K489-7
K466-2
K613-7
K1546-1
K1546-2
K435
K468
K363P
K438
K1504-1
Gun Receiver Bushing (for Lincoln
Fast-Mate guns.)
Includes: Gun receiver bushing with trigger connector.
Magnum 200/300/400 to K1500-2
Adapter.
Includes: Gun adapter, cotter pin, hex key wrench, wrench.
Magnum 550 to K1500-3 Adapter
Lincoln Conduit.
Includes: Trigger adapter, gun adapter and hex key wrench.
Incoming Bushing, for Lincoln
Conduit .025- 1/16" (0.6 - 1.6mm) wire.
Includes: Incoming bushing and hex key wrench.
Incoming Bushing, for Lincoln
Conduit 1/16-1/8" (1.6 - 3.2 mm ) wire.
Spindle Adapter, for mounting 14 lb. (6.4 kg) Innershield Coils on 2 in (51 mm) spindles.
Includes: Incoming bushing and hex key wrench.
Includes: Spindle Adapter made from 2 coil retainers.
(Electrode not included.)
Includes: Spindle Adapter.
Spindle Adapter, for mounting 8in
(203mm) diameter spools on 2 in
(51 mm) spindles.
Readi-Reel Adapter, for mounting
23-30 lb. (10.4 - 13.6 kg) reels to 2 in (51 mm) spindles.
Includes: Readi-Reel spool adapter. (Spool of electrode not included.)
Readi-Reel Adapter, for mounting
50-60 lb. (22.7 - 27.2 kg) reels to
2 in (51 mm) spindles. For use with Heavy Duty Bench models.
Includes: Readi-Reel spool adapter. (Spool of electrode not included.)
Coil Adapter, for mounting 50-60 lb. (22.7 - 27.2 kg) coils to 2 in (51 mm) spindles.
For use with heavy Duty Bench
Includes: 50-60 lb. (22.7 -
27.2 kg) coil adapter.
C-4
LF-72/74
C-5
ACCESSORIES
OPTIONAL KITS:
K1634-1
K1634-2
K659-1
3000290
K586-1
K1524-3
K163
K1557-1
K1556-1
Plastic Wire Cover for 30-44 lb.
(13.6 - 20.0 kg) Wire packages.
(For use with Standard Duty
Bench Models and Heavy Duty
Bench Models.)
Includes: Cover, backing plate, wire conduit, incoming bushing for .025 - 1/16" (0.6 -
1.6 mm) wire, incoming bushing for 1/16" - 1/8" (1.6 - 3.2
mm) wire, thumb screw, mounting hardware and hex key.
Plastic Wire Cover for up to 60 lb.
(27.2kg) Wire packages. (For use with Heavy Duty Bench Models.)
Gas Guard Regulator Includes: Gas Guard
Regulator and adjustment key.
Adjustable Gas Regulator
Deluxe Adjustable Gas Regulator
Includes: Gas Regulator for
Mixed Gases and 10' (3.0m)
Hose.
Includes: Deluxe Gas
Regulator for Mixed Gases,
Adapter for CO2 and 10'
(3.0m) Hose.
Includes: Heavy Duty Wire
Reel Stand.
Heavy Duty Universal Wire Reel
Stand. For spools up to 60 lb.
(27.2kg)
4 Wheeled Wire Feeder
Undercarriage (For use with
Standard Duty Bench Models and
Heavy Duty Bench Models.)
Includes: Undercarriage with
8" (203mm) rear wheels, 4"
(102mm)casters.
Swivel Platform (for use with
Heavy Duty Bench Models)
Includes: Swivel Platform and
Tray.
Light Duty Caster Kit (for use with
Heavy Duty Bench Models)
Includes: 2 Swivel Casters, 2
Fixed Casters, brackets and mounting hardware.
K1555-1
Insulated Lift Bail
(for use with Heavy Duty Bench
Models)
Includes: Insulated Lift Bail and mounting hardware.
C-5
LF-72/74
C-6
NOTES
C-6
LF-72/74
Section D-1
TABLE OF CONTENTS
- MAINTENANCE SECTION -
Section D-1
Maintenance ...........................................................................................................Section D
LF-72/74 SINGLE/DUAL
D-2
MAINTENANCE
Safety Precautions
WARNING
ELECTRIC SHOCK can kill.
MAINTENANCE
CALIBRATION SPECIFICATION
WARNING
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts such as output terminals or internal wiring.
• When inching with gun trigger, electrode and drive mechanism are “hot” to work and ground and could remain energized several seconds after the gun trigger is released.
• Turn OFF input power at welding power source before installation or changing drive roll and/or guide tubes.
• Welding power source must be connected to system ground per the National Electrical Code or any applicable local codes.
D-2
• Do not touch electrically live parts.
• When inching with the gun trigger, electrode, wire drive motor and drive mechanism are "hot" to work and ground and could remain energized several seconds after the gun trigger is released.
• Welding power source must be connected to system ground per the National Electrical Code or any applicable local codes.
• Only qualified personnel should perform maintenance work.
------------------------------------------------------------------------
Calibration of the LF-72 may be required when the p.c.
board, potentiometer or motor is replaced or serviced.
Calibration matches the scale on the name plate to the actual wire feed speed.
• Only qualified personnel should perform maintenance work.
------------------------------------------------------------------------
Observe all additional Safety Guidelines detailed throughout this manual.
ROUTINE MAINTENANCE
• Clean and tighten all weld terminals.
• Inspect all weld cables, control cables, gun cables and shielding gas hoses. Repair or replace as necessary.
To verify if calibration is necessary:
1. Turn off power to the LF-72.
2. Assemble .045 drive rolls, inner guide and the outer guide into the drive. Remove the gun from the wire feeder if assembled.
3. Load .045 wire into the drive. Cut the wire flush with the end of the gun bushing.
4. Set the WFS knob to 300 ipm.
5. Using the COLD FEED switch, feed wire for 10 seconds.
6. Cut the wire flush with the end of the gun bushing.
Measure the length of the wire. If the wire measures 50 ± 2.5 inches then calibration is not required.
PERIODIC MAINTENANCE
•
Clean drive roll grooves.
• Blow out or vacuum the inside of the feeder.
Tools required:
5/16" nut driver
3/4" open end wrench
WFS meter or RPM meter
Shorting plug. The shorting plug shorts pins 1
& 5 of connector J2 on the p.c. board. J2 is a
6 pin molex connector.
To calibrate the LF-72:
1. Turn off power to the LF-72.
2. Disconnect the electrode lead from the feedplate and from the welding power source.
3. Remove the 5 screws securing the wraparound.
(The door is not shown for clarity. “
LF-72/74
D-3
MAINTENANCE
FIGURE D.1
D-3
4. Open the idle arm.
5. Turn power on to the LF-72.
6. Adjust the WFS knob to 300 ipm. Center the knob pointer with the name plate graphics.Activate the gun trigger.
7. Insert the shorting plug into connector J2 on the p.c.
board. The shorting plug shorts pins 1 & 5.
(See Figure D.2)
8. Remove the shorting plug. Set aside.
(For Codes below 11289 use 9 thru 17)
9. Adjust the WFS knob to minimum.
10. Insert the shorting plug into connector J2.
11. Adjust the WFS knob until the motor measures 51
± 5.5 ipm. (9.5 ± 1.0 rpm).
12. Remove the shorting plug.
13. Adjust the WFS knob to maximum.
14. Insert the shorting plug into connector J2.
15. Adjust the WFS until the motor measures 793 ±
5.5 ipm (146.7 ± 1.0 rpm.)
16. Remove the shorting plug.
17. Release the gun trigger.
(For Codes above 11290 use 18)
18. Replace P2 from the harness into connector J2.
19. Turn off power.
20. Secure the wraparound to the LF-72 with 5 screws.
FIGURE D.2
J2 CONNECTOR
LF-72/74 SINGLE/DUAL
D-4
1. Center Assembly
2. Wire Drive Assembly
3. Wire Reel Stand LF-72
4. Wire Reel Stand LF-74
MAINTENANCE
D-4
2
FIGURE D.3 - MAJOR COMPONENT LOCATION
3
4
1
LF-72/74
Section AA-1
TABLE OF CONTENTS
- INSTALLATION SECTION -
Section AA-1
Installation ............................................................................................................Section AA
Welding Gun/Wire Feeder Trigger Connector ......................................................AA-9
Base Model, Bench Model and Extra Torque Bench Model ...................................AA-19
LF-72/74
AA-2
INSTALLATION
TECHNICAL SPECIFICATIONS: LF-74 Wire Feeder
AA-2
SPEC.#
Model
K2426-1
TYPE
Gearing
Normal Speed
GMAW
WIRE FEED SPEED RANGE
WFS Range Wire Sizes
FCAW
WFS Range
100 – 800 ipm
(2.5-20.3 m/min.)
.023 – 1/16"
(0.6 – 1.6mm)
100 – 800 ipm
(2.5-20.3 m/min.)
Wire Sizes
.030 - 5/64”
(0.8 - 2.0mm)
K2426-2 Normal Speed 100 – 800 ipm
(2.5-20.3 m/min.)
.023 – 1/16"
(0.6 – 1.6mm)
100 – 800 ipm
(2.5-20.3 m/min.)
.030 – 5/64"
(0.8 – 2.0mm)
K2426-3 Extra Torque
50 – 400 ipm
(1.3 – 10.4m/min)
.023 – 1/16"
(0.6 – 1.6mm)
CONTROL BOX, WIRE DRIVE AND COMPLETE UNITS
SPEC.# TYPE INPUT POWER PHYSICAL SIZE•
50 – 400 ipm
(1.3 – 10.4m/min)
.030 – 3/32"
(0.8 - 2.4mm)
TEMPERATURE RATING
Input Voltage and Current Height
Dimensions
Width Depth Weight Operating Storage
K2426-1
LF-74 11.1“
( 282 mm)
10.2“ 12.9“ 46 Lbs.
(259 mm) (328 mm) (20.9 Kg.)
Base Model
Height
Dimensions
∆
Width Depth Weight
LF-74
K2426-2
Bench
Heavy
Duty
24-42VAC
9 AMPS
50/60 Hz
15.3“
( 389 mm)
13.0“
(330 mm)
27.7“ 70.5 Lbs. 14°F to 104°F -40°F to 85°F
(704 mm) (32.0 Kg.) (-10°C to 40°C) (-40°C to 85°C)
Height
LF-74
K2426-3 Bench
Heavy
Duty
Extra Torque
WELDING CAPACITY RATING
Amp Rating Duty Cycle
600 A
500 A
60%
100%
∆ Dimensions do not include wire reel.
15.3“
( 389 mm)
Dimensions
∆
Width Depth Weight
13.0“ 27.7“ 70.5 Lbs.
(330 mm) (704 mm) (32.0 Kg.)
Model
K2426-1
Description
Base Model
ITEMS INCLUDED WITH EACH PRODUCT
Wire
Feeder
Wire Reel Stand Drive Roll Kit
-----------
Control Cable
K2426-2 Bench Model with
Heavy Duty Wire
Stand
K2426-3 Extra Torque
Model with Heavy
Duty Wire Stand
LF-74 Heavy Duty, up to 60lb.
(27.k kg) Coils
.035, .045 Combo
(0.9, 1.2mm)
LF-72/74
10Ft. (3m)
AA-3
INSTALLATION
MOUNTING
SAFETY PRECAUTION
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the welding power source before installation or changing drive rolls and/or guides.
AA-3
For location and size,
LF-74 Bench Model Rear
Mounting Holes (See Figure AA.1) and for Bottom
Mounting Holes (See Figure AA.2).
• Do not touch electrically live parts.
• When inching with the gun trigger, electrode and drive mechanism are "hot" to work and ground and could remain energized several seconds after the gun trigger is released.
• Welding power source must be connected to system ground per the National Electrical Code or any applicable local codes.
• Only qualified personnel should perform maintenance work.
FIGURE AA.1
----------------------------------------------------------------------------------------
LOCATION
The LF-74 may be placed on a bench, mounted on top of a welding power source or assembled to an appropriate boom.
Place the LF-74 in a clean and dry location.
Do not stack the LF-74.
FIGURE AA.2
1/4-20 THREADS
5/16-18 THREADS
LF-72/74
AA-4
BENCH MOUNT
INSTALLATION
BOOM MOUNT
The LF-74 mounts in a variety of configurations. As shipped from the factory, the LF-74 is suitable for bench mounting or placing directly on top of the welding power source (CV-xxx and DC-xxx product family only).
Bench Mount
AA-4
When boom mounting, remove the wire reel stand (if assembled) and secure the wire feeder directly to the desired surface.
SWIVEL MOUNT
The base model and heavy duty bench models may be mounted onto a swivel when a top a welding power source.
SUSPENDED
Only suspend the wire feeder by the handle/lift bail of the portability kit.
K2426-1 shown with K2328-1Standard Duty Wire Reel
Stand and K2331-1 Lift Bail
K1557-1Swivel Kit and Bench Model, with Heavy
Duty Wire Reel Stand.
K2332-1 Swivel Kit and Base Model LF-74
WARNING
Alternative methods for hanging the wire feeder must not be used unless insulation is provided between the wire feeder enclosure and the hanging device.
------------------------------------------------------------------------
LF-72/74
AA-5
INSTALLATION
SAFETY PRECAUTION
ELECTRIC SHOCK can kill.
• Only qualified personnel should perform this installation.
• Turn off the input power to the power source at the disconnect switch or fuse box before working on this equipment. Turn off the input power to any other equipment connected to the welding system at the disconnect switch or fuse box before working on this equipment.
• Do not touch electrically hot parts.
----------------------------------------------------------------------
WELD CABLE SIZES
Table A.1 has the copper cable sizes recommended for different currents and duty cycles. Lengths stipulated are the distance from the welder to work and back to the welder again. Cable sizes are increased for greater lengths primarily for the purpose of minimizing voltage in the welding circuit.
TABLE AA.1
RECOMMENDED CABLE SIZES (RUBBER COVERED COPPER - RATED 75°C)**
AA-5
CABLE SIZES FOR COMBINED LENGTHS OF ELECTRODE AND WORK CABLES
Amperes
Percent
Duty
Cycle
0 to 50 Ft.
0 to 15 m
50 to 100Ft.
15 to 31 m
100 to 150 Ft.
31 to 48 m
150 to 200 Ft.
48 to 61 m
200 to 250 Ft.
61 to 76 m
200
200
225
225
250
60
100
20
40 & 30
30
2
2
4 or 5
3
3
2
2
3
3
3
2
2
2
2
2
1
1
1
1
1
250
250
250
300
40
60
100
60
2
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1/0
1/0
1/0
1/0
2/0
325
350
400
400
500
100
60
60
100
60
2/0
1/0
2/0
3/0
2/0
2/0
1/0
2/0
3/0
2/0
2/0
2/0
2/0
3/0
3/0
2/0
2/0
3/0
3/0
3/0
3/0
3/0
4/0
4/0
4/0
** Tabled values are for operation at ambient temperatures of 40°C and below. Applications above 40°C may require cables larger than recommended, or cables rated higher than 75°C.
1/0
1/0
1/0
1/0
1/0
LF-72/74
AA-6
COAXIAL WELD CABLES
INSTALLATION
Coaxial welding cables are specially designed welding cables for pulse welding welding. Coaxial weld cables feature low inductance, allowing fast changes in the weld current. Regular cables have a higher inductance which may distort the pulse wave shape. Inductance becomes more severe as the weld cables become longer.
WELD CABLE CONNECTION
AA-6
A coaxial weld cable is constructed by 8 small leads wrapped around one large lead. The large inner lead connects to the electrode stud on the power source and the electrode connection on the wire feeder. The small leads combine together to form the work lead, one end attached to the power source and the other end to the work piece. (See Coaxial weld Cable below.)
Coaxial weld cables are recommended for all pulse welding, especially when the total weld cable length
(electrode cable + work cable) exceeds 50 feet (7.6m).
Connect a work lead of sufficient size between the proper output stud on the power source and the work.
Be sure the connection to the work makes tight metal to metal electrical contact. Poor work lead connections can result in poor welding performance.
Coaxial Weld Cable
Work
Electrode
Work
Power Source
Work
Electrode
Coaxial Weld Cable
Wire Feeder
Electrode
Work
LF-72/74
AA-7
INSTALLATION
ANALOG CONTROL CABLE
CONTROL CABLE CONNECTIONS
K1797-xx
The control cable connecting the wire feeder to the power source is specially made for the welding environment.
The wire feeder power requires overcurrent protection.
Connect the wire feeder only to power sources with overcurrent protection of no more than 15 amps.
POWER SOURCE
J
I
H
G
N
F
K
A
B
M
L
E
D
C
WIRE FEEDER
A
B
C
L
D
E
K
J
I
M
N
G
H
F
PIN
A
B
C
D
E
F
G
H
J
I
FUNCTION LEAD#
Reserved
Reserved
Welding Output Control
(trigger from feeder)
Welding Output Control
(trigger from feeder)
Remote Voltage Control
(“+” supply from feeder or remote)
-------
-------
2
4
77
Remote Voltage Control
(control signal from feeder or remote)
Remote Voltage Control
(“-” supply from feeder or remote)
76
75
Reserved
42 VAC 41
Reserved
K
L
42 VAC
Reserved
42
M
N
Reserved
Electrode voltage from feeder
-------
67
Do not use more than 100 ft (30.5 m) of control cable between the wire feeder and power source.
LF-72/74
AA-7
AA-8
INSTALLATION
ANALOG MILLER CONTROL CABLE
ADAPTER K2335-1
This Lincoln Electric wire feeder may be mounted to a limited number of Miller Electric power sources. The
Miller power source must have the circular connector pin definition shown in the table below for proper operation of the wire feeder. Be sure the Miller power source provides 24 VAC to the wire feeder and has overcurrent protection of no more than 15 amps. The power source must not exceed 113VDC peak.
Operation of Lincoln wire feeders on Miller power sources may result in lack of high wire feed speeds or reduced pull force at high wire feed speeds.
Approximate maximum WFS for Lincoln wire feeders operating with 24 VAC:
LF-72
LF-74
LF-74, extra torque
720 ipm
720 ipm
360 ipm
AA-8
Pin
D
E
F
A
B
C
G
H
POWER SOURCE
H
I
J
N
G
F
A
K
B
M
L
D
C
E
MILLER POWER SOURCE
Function Pin
24 VAC to feeder
Welding Output Control
+10VDC to feeder for remote control
Remote control common
0-10VDC from feeder for remote control.
F
Current feedback to feeder.
Scaled 0-10V. 1 V = 100 amps.
Referenced to pin D.
24 VAC common.
Arc Voltage feedback to feeder.
Scaled 0-10V. 1 V = 10 Arc volts.
Referenced to pin D.
K
L
J
I
D
C
E
G
WIRE FEEDER
C
B
A
L
D
E
J
K
I
N
M
F
G
H
LINCOLN WIRE FEEDER
Function
42 VAC feeder
Welding Output Control
Welding Output Control
Remote Voltage Control ("+" supply, from power source)
Remote Voltage Control ("-" supply, from power source)
Remote Voltage Control (control signal from feeder or remote.)
Reserved for future use.
42 VAC to feeder
Reserved for future use.
N N Electrode voltage to power source (67)
Miller is a registered trademark not owned or licensed by The Lincoln Electric Company.
LF-72/74
AA-9
INSTALLATION
WELDING GUN/WIRE FEEDER TRIGGER
CONNECTOR
Drive Roll Kits, Cored Wires
Includes: 4 Knurled drive rolls and inner wire guide.
AA-9
Wire Feeder
Amphenol
A
B
E
D
C
Trigger Lead
Welding G un
KP1505-035C
KP1505-045C
KP1505-052C
KP1505-1/16C
.030-.035" (0.8-0.9mm)
.040-.045" (1.0-1.2mm)
.052" (1.4mm)
1/16" (1.6mm)
Drive Roll Kits, Steel or Cored Wires
Includes: 4 Knurled drive rolls and inner wire guide.
Wire Feeder
Pin
A
B
C
D
E
-
-
-
Function
Gun Trigger
Common
KP1505-068
KP1505-5/64
KP1505-3/32
.068-.072" (1.8mm)
5/64" (2.0mm)
3/32" (2.4mm)
HIGH FREQUENCY PROTECTION
Drive Roll Kits, Aluminum Wire
Includes: 4 polished U groove drive rolls, outer wire guide and inner wire guide.
Locate the LF-74 away from radio controlled machinery. The normal operation of the LF-74 may adversely affect the operation of RF controlled equipment, which may result in bodily injury or damage to the equipment.
KP1507-035A
KP1507-040A
KP1507-3/64A
KP1507-1/16A
.035" (0.9 mm)
.040" (1.0mm)
3/64" (1.2mm)
1/16" (1.6mm)
REMOTE SENSE LEAD SPECIFICATIONS
DRIVE ROLLS
Refer to the power source instruction manual for instructions for connecting the wire feeder for STT welding.
WIRE DRIVE SYSTEMS
Drive Roll Kits, Steel Wires
Includes: 4 Smooth V groove drive rolls and inner wire guide.
KP1505-030S
KP1505-035S
KP1505-045S
KP1505-052S
KP1505-1/16S
.023-.030 (0.6-0.8mm)
.035 (0.9mm)
.045 (1.2mm)
.052 (1.4mm)
1/16 (1.6mm)
INNER WIRE
GUIDE
LF-72/74
AA-10
INSTALLATION
WELDING GUNS, TORCHES AND ACCES-
SORIES
AA-10
3. Fully insert the gun cable connector end into the gun receiver bushing and gently tighten the thumb screw as show in Figure AA.3 below.
GUN RECEIVER BUSHING
The LF-74 wire feeder comes with a K1500-2 gun receiver bushing.
4. Connect the gun trigger connector to the trigger receptacle. Make sure that the key ways are aligned and insert.
MAGNUM GUN AND CABLE ASSEMBLIES
The LF-74 wire feeder model will accept a number of optional gun and cable assemblies. An example of installing the Gun and Cable is shown in Figure AA.3
with a 15 ft. (4.6m) long Magnum 400 gun and cable.
1. Turn off power at the welding power source.
2. Unscrew Thumb screw on Wire Drive Unit, until tip of screw no longer protrudes into gun bushing hole as seen from the front of machine.
FIGURE AA.3
LF-72/74
AA-11
INSTALLATION
WIRE DRIVE CONFIGURATION
(See Figure AA.5)
Changing the Gun Receiver Bushing
WARNING
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the welding power source before installation or changing drive rolls and/or guides.
• Do not touch electrically live parts.
• When inching with the gun trigger, electrode and drive mechanism are "hot" to work and ground and could remain energized several seconds after the gun trigger is released.
• Only qualified personnel should perform maintenance work.
------------------------------------------------------------------------
Tools required:
• 1/4" hex key wrench
Note: Some gun bushings do not require the use of the thumb screw.
AA-11
7. Disconnect the shielding gas hose from the gun bushing, if required.
8. Connect the shielding gas hose to the new gun bushing, if required.
9. Rotate the gun bushing until the thumb screw hole aligns with the thumb screw hole in the feed plate.
Slide the gun receiver bushing into the wire drive and verify the thumb screw holes are aligned.
10. Tighten the socket head cap screw.
11. Insert the welding gun into the gun bushing and tighten the thumb screw.
Gun Receiver
Bushing
K1500-1
K1500-2
For use With
K466-1 Lincoln gun connectors;
Innershield and Subarc guns)
K466-2, K466-10 Lincoln gun connectors; Magnum 200/300/400 guns and compatible with Tweco®
#2 - #4)
1. Turn power off at the welding power source.
2. Remove the welding wire from the wire drive.
3. Remove the thumb screw from the wire drive.
4. Remove the welding gun from the wire drive.
K1500-3
5. Loosen the socket head cap screw that holds the connector bar against the gun bushing.
Important:
Do not attempt to completely remove the socket head cap screw.
K1500-4
6. Remove the outer wire guide, and push the gun bushing out of the wire drive. Because of the pre-
K1500-5 cision fit, light tapping may be required to remove the gun bushing.
K489-7
FIGURE AA.5
K1637-7 Lincoln gun connectors;
Magnum 550 guns and compatible with Tweco® #5)
K466-3 Lincoln gun connectors; compatible with Miller® guns.)
(Compatible with Oxo® guns.)
( Lincoln Fast-Mate guns.)
GUN RECEIVER BUSHING
LOOSEN
CAP
SCREW
TIGHTEN
CAP
SCREW
THUMB
SCREW
CONNECTOR
BAR
SOCKET
HEAD CAP
SCREW
LF-72/74
AA-12
INSTALLATION
ASSEMBLY OF DRIVE ROLLS AND WIRE
GUIDES
WARNING
To install drive rolls and wire guides:
(See Figure AA.7 and AA.7a)
1. Turn off power at the welding power source.
AA-12
2. Open pressure arms.
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the welding power source before installation or changing drive rolls and/or guides.
• Do not touch electrically live parts.
• When inching with the gun trigger, electrode and drive mechanism are "hot" to work and ground and could remain energized several seconds after the gun trigger is released.
• Only qualified personnel should perform maintenance work.
------------------------------------------------------------------------
To remove drive rolls and wire guides:
(See Figure AA.6)
3. Assemble the inner wire guide.
4. Slide the drive rolls onto the drive hubs.
(See figure
AA.7)
5. Close the pressure arms.
6. Rotate 4 triangular rings to the locked position. (See figure
AA.7a)
7. Assemble the outer wire guide.
8. Adjust the pressure arms to the recommended setting.
FIGURE AA.7
1. Turn power off at the welding power source.
2. Remove the outer wire guide.
3. Rotate 4 triangular rings to the unlocked position.
4. Open the pressure arms.
5. Remove the drive rolls and inner wire guide.
DRIVE HUBS
PRESSURE ARMS
IN OPEN POSITION
INNER WIRE GUIDE
DRIVE ROLLS
FIGURE AA.6
2 PRESSURE ARMS
ROTATE DOWN
FIGURE AA.7a
4 TRIANGULAR RINGS
IN UNLOCKED POSITION
TRIANGULAR RING IN
UNLOCKED POSITION
SLIDE DRIVE ROLL
ON DRIVE HUB
TRIANGULAR RING IN
LOCKED POSITION
OUTER WIRE GUIDE
LF-72/74
AA-13
INSTALLATION
PRESSURE ARM ADJUSTMENT
WARNING
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the welding power source before installation or changing drive rolls and/or guides.
• Do not touch electrically live parts.
• When inching with the gun trigger, electrode and drive mechanism are "hot" to work and ground and could remain energized several seconds after the gun trigger is released.
• Only qualified personnel should perform maintenance work.
------------------------------------------------------------------------
The pressure arm controls the amount of force the drive rolls exert on the wire. Proper adjustment of both pressure arm gives the best welding performance. For best results, set both pressure arms to the same value.
Set the pressure arm as follows (See Figure AA.8):
Aluminum wires between 1 and 3
Cored wires between 3 and 4
Steel, Stainless wires between 4 and 6
FIGURE AA.8
AA-13
CORED WIRES
OUTERSHIELD
METALSHIELD
INNERS HIELD
1
3
5
2
4
6
SOLID WIRES
ALUMINUM
STEEL
STAINLE SS
LF-72/74
AA-14
INSTALLATION
SHIELDING GAS CONNECTION
CYLINDER may explode if damaged.
AA-14
6. Before opening the cylinder valve, turn the regulator adjusting knob counterclockwise until the adjusting spring pressure is released.
• Keep cylinder upright and chained to support.
• Keep cylinder away from areas where it may be damaged.
• Never lift welder with cylinder attached.
• Never allow welding electrode to touch cylinder.
• Keep cylinder away from welding or other live electrical circuits.
------------------------------------------------------------------------
BUILD-UP OF SHIELDING GAS may harm health or kill.
7. Standing to one side, open the cylinder valve slowly a fraction of a turn. When the cylinder pressure gage stops moving, open the valve fully.
8. The flow regulator is adjustable. Adjust it to the flow rate recommended for the procedure and process being used before making a weld.
• Shut off shielding gas supply when not in use.
SEE AMERICAN NATIONAL STANDARD Z-49.1,
"SAFETY IN WELDING AND CUTTING" PUB-
LISHED BY THE AMERICAN WELDING SOCIETY.
------------------------------------------------------------------------
Maximum inlet pressure is 100 psi. (6.9 bar.)
Install the shielding gas supply as follows:
1. Secure the cylinder to prevent it from falling.
2. Remove the cylinder cap. Inspect the cylinder valves and regulator for damaged threads, dirt, dust, oil or grease. Remove dust and dirt with a clean cloth.
DO NOT ATTACH THE REGULATOR IF OIL,
GREASE OR DAMAGE IS PRESENT! Inform your gas supplier of this condition. Oil or grease in the presence of high pressure oxygen is explosive.
3. Stand to one side away from the outlet and open the cylinder valve for an instant. This blows away any dust or dirt which may have accumulated in the valve outlet.
4. Attach the flow regulator to the cylinder valve and tighten the union nut(s) securely with a wrench.
Note: if connecting to 100% CO
2 cylinder, insert regulator adapter between regulator and cylinder valve.
If adapter is equipped with a plastic washer, be sure it is seated for connection to the CO
2 cylinder.
5. Attach one end of the inlet hose to the outlet fitting of the flow regulator. Attach the other end to the welding system shielding gas inlet. Tighten the union nuts with a wrench.
LF-72/74
AA-15
WIRE REEL LOADING
WARNING
INSTALLATION
AA-15
3. Re-install the retaining collar. Make sure that the release bar snaps out and that the retaining collar fully engages the groove on the spindle.
FIGURE AA.10
• Keep hands, hair, clothing and tools away from rotating equipment.
• Do not wear gloves when threading wire or changing wire spool.
• Only qualified personnel should install, use or service this equipment.
-----------------------------------------------------------------------
Retaining
Collar
Loading 10 to 15 lb. (4.5 – 6.8kg) Spools
A K468 spindle adapter is required for loading 2" wide spools on 2" (51mm) spindles. Use a K468-1 spindle adapter for loading 2-1/2" (64mm) wide spools. (See figure AA.9 and figure AA.10)
1. Squeeze the release bar on the retaining collar and remove it from the spindle.
2. Place the spindle adapter on the spindle, aligning the spindle brake pin with the hole in the adapter.
3. Place the spool on the spindle and align the adapter brake tab with one of the holes in the back side of the spool. An indicator mark on the end of the spindle shows the orientation of the brake tab. Be certain the wire feeds off of the spool in the proper direction.
4. Re-install the retaining collar. Make sure that the release bar snaps out and that the retaining collar fully engages the groove on the spindle.
FIGURE AA.9
Adapter
Loading 30 lb. (13.6 kg) Readi-Reels
A K363-P Readi-Reel adapter is required for loading these spools on 2" (51mm) spindles.
1. Squeeze the release bar on the retaining collar and remove it from the spindle.
2. Place the Readi-Reel adapter on the spindle, aligning the spindle brake pin with one of the holes in the adapter.
3. Re-install the retaining collar. Make sure that the release bar snaps out and that the retaining collar fully engages the groove on the spindle.
4. Rotate the spindle and adapter until the retaining spring is at the 12 o’clock position.
5. Position the Readi-Reel so that electrode de-reels in the proper direction.
6. Set one of the Readi-Reel inside cage wires on the slot in the retaining spring.
7. Lower the Read-Reel to depress the retaining spring and align the other inside cage wires with the grooves in the adapter.
8. Slide the cage all way onto the adapter until the retaining spring "pops up" fully.
Removing a Readi-Reel
Spindle Placement
The wire reel stand provides two mounting locations for the spindle. Each mounting location consists of a tube in the center of the mast and locating slots.
Loading 16 to 44 lb. (7.3 – 20kg) Spools
1. Squeeze the release bar on the retaining collar and remove it from the spindle.
2. Place the spool on the spindle, aligning the spindle brake pin with one of the holes in the back side of the spool. An indicator mark on the end of the spindle shows the orientation of the brake holding pin.
Be certain the wire feeds off of the spool in the proper direction.
1. To remove a Readi-Reel from the an adapter, depress the retaining spring with a thumb while pulling the Readi-Reel cage from the adapter with both hands. Do not remove the adapter from the spindle.
LF-72/74
AA-16
INSTALLATION
FIGURE AA.11
AA-16
WELD WIRE ROUTING
The electrode supply may be either from reels, Readi-
Reels, spools, or bulk packaged drums or reels.
Observe the following precautions: a) The electrode must be routed to the wire drive unit so that the bends in the wire are at a minimum, and also that the force required to pull the wire from the reel into the wire drive unit is kept at a minimum.
b) The electrode is “hot” when the gun trigger is pressed and must be insulated from the boom and structure.
c) If more than one wire feed unit shares the same boom and are not sharing the some power source output stud, their wire and reels must be insulated from each other as well as insulated from their mounting structure.
LF-72/74
AA-17
INSTALLING ELECTRODE
CONDUIT KITS
INSTALLATION
AA-17
4. Loosen the set screw on the feed plate and remove the incoming bushing.
FIGURE AA.12a
WARNING
SET
SCREW
CONDUIT
CONNECTOR
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the disconnect switch before working on this equipment.
• Do not touch electrically hot parts.
------------------------------------------------------------------------
Electrode conduit is used when feeding from wire drums, boxes or large reels. For best feeding results, use the shortest conduit length possible and avoid sharp bends.
Tools required:
• 1/8" Hex key wrench
• 5/16" Nut Driver
To install Lincoln conduit:
1. Turn off power at the welding power source.
FIGURE AA.12
MOUNTING SCREWS *
SECURING WIRE DRIVE PANEL
THUMB
SCREW
5. Insert the conduit connector into the feed plate and secure with the set screw. Rotate the conduit connector so the thumb screw does not interfere with the idle arm or door.
6. Mount the wire drive panel to the sheet metal housing with the six screws.
7. Insert conduit through the sheet metal of the LF-74 and into the conduit connector. Secure with the thumb screw.
INCOMING
BUSHING
BALL
BUSHING
ASSEMBLY
O-RING
SET SCREW
MOUNTING SCREWS*
SECURING WIRE DRIVE PANEL
*REMOVE 6 MOUNTING SCREWS
2. Remove the o-ring holding the ball bushing assembly to the back of the wire feeder. Remove the ball bushing assembly.
3. Remove the six screws securing the wire drive panel to the sheet metal housing.
LF-72/74
AA-18
INSTALLATION
ALUMINUM WIRE PREPARATIONS
WARNING
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the disconnect switch before working on this equipment.
• Do not touch electrically hot parts.
------------------------------------------------------------------------
Welding with aluminum filler wires requires extra care.
Aluminum wire is softer and not as stiff as steel wires, it is important to keep aluminum wire free of dirt and scratches. Limit gun length to 10 Ft.(3.0 m) for best results and use a spool cover if feeding from a spool.
To prevent scratching of the aluminum wire, remove the ball bearings from the ball housing as follows.
Tools required: (See Figure AA.12b)
• 9/64" Hex key wrench
1. Turn off power at the welding power source.
2. Remove the o-ring holding the ball bushing assembly to the back of the wire feeder. Remove the ball bushing assembly.
FIGURE AA.12b
FIGURE AA.13
AA-18
4. Place the ball bushing housing into the wire feeder case and secure with the “O” ring.
"O" RING
3. Remove the three socket head cap screws from the ball bushing assembly.
Caution: as the screws are being loosened, the balls may fall free from the
assembly. Remove the balls and the steel washer.
LF-72/74
AA-19
INSTALLATION
BASE MODEL (K2426-1)
AA-19
BENCH MODEL WITH HEAVY DUTY WIRE STAND (K2426-2)
EXTRA TORQUE BENCH MODEL WITH HEAVY DUTY WIRE STAND (K2426-3)
LF-72/74
AA-20
COMMON EQUIPMENT SET-UPS
INSTALLATION
FIGURE AA.14 GENERAL FABRICATION
AA-20
Item
1A
1B
1C
1D
2A
2B
3
4A
4B
5
K#
K2426-2
See welding gun literature
K586-1
K1557-1
K1803-1
K2400-1
Description
LF-74 Bench Model with Heavy Duty Wire Reel Stand
.035, .045 (0.9mm, 1.2mm) Drive Roll Kit
10' (3m) Control Cable
Magnum Gun
Deluxe Regulator for Mixed Shielding Gases
Shielding Gas Hose
Swivel Kit
Ground Clamp
Weld Power Cables, Twist-Mate to Lug (2 included)
CV-305
LF-72/74
AA-21
FIGURE AA.15 HIGH VOLUME
PRODUCTION
INSTALLATION
AA-21
Item
1A
1B
1C
-
1D
2
3
4
5A
5B
6
7
8
9
10
11
K#
K2426-1
K1797-xx
See Welding Gun Literature
K2329-1
K2330-1
See Welding Arm Literature
K586-1
K884-xx
K2175-xx
K1346-13
K910-xx
K1842-xx
K1546-1
Description
LF-74, Base Model
.035, .045 (0.9, .1.2mm) Drive Roll Kit
10' (3m) Control Cable.
Control Cable Extension
Welding Gun
Remote Voltage Control Kit
Timer Kit
Welding Arm
Deluxe Gas Regulator for Mixed Gases
Shielding Gas Hose
Accu-Trak Drum Payoff Kit (Round)
Accu-Pak Box Payoff Kit (Square)
CV-400
Ground Clamp
Weld Power Cable, Lug to Lug
Incoming Bushing, .035-1/16 (0.9 - 1.6 mm)
Conduit
LF-72/74
AA-22
1
INSTALLATION
FIGURE AA.16 PORTABLE WELDING
7
2
3A
5A
6
7A
3C, 4
AR NIN
RE MO TE
ON
OF
PO ER
elit, Lore ree
Lore ree ipsu lore t do lore gna dolo gna r sit uam dolo um aliq ons am uam ecte m ip Lore re m uism era r ad sum dolo ecte tinc ipis
Lore ipsu uam euis ipis nt u
Lore ipsu re m dolo dolo uam euis ecte i cin
Lore ipsu uam ecte d tin dolo euis cidu
Lore ipsu uam cidu ecte
Lore dolo h eu i cin ipsu uam ecte cidu d tin
Lore dolo euis i cin
W dolo uam euis ecte cidu d tin uam ecte d tin d tin i cin euis cidu
W AR
NIN
G
G cidu ecte i cin
Lore ipsu
Lore ipsu re m
Lore ipsu Lore ipsu dolo
AV dolo uam h eu
AT
ISO uam euis ecte cidu d tin uam h eu uam d tin ecte cidu cidu d tin cing i cin d tin i cin cidu cing i cin
TE
AU i cin
DE
IO
N
N ree t do lore
Lore ree ipsu ma ipsu lore gna aliq gna gna uam r sit aliq euis mo am h e era tetu
Lore ecte er a unt ipsu tue ipis iscin ipsu Lore dolo r ad ipis ipsu Lore dolo uam euis
Lore sum re m dolo uam d tin ecte uam ecte cidu euis d tin ecte cidu cidu i cin iscin uam ecte cidu d tin iscin ecte d tin iscin cidu
P
O
W
E
R
W
A
V
E
3
5
5
10
9
5C
AA-22
8
3D
5C
6
7
7A
8
9
Item
1
2
3A
3C
3D
4
5A
10
K#
See Welding Gun Literature
K2329-1
K2426-3
KPxxx
K1797-xx
K2331-1
K163
K1634-2
K586-1
K1803-1
See Power Source or Engine
Drive Literature
Description
Lincoln InnerShield Gun.
Remote Voltage Control Kit.
LF-74 Extra Torque Bench Model with Heavy Duty Wire Reel Stand
10' (3m) Control Cable.
.035, .045 (0.9, 1.2mm)Drive roll Kit
Control Cable Extension. Add cables to extend up to 110' (30m)
Insulated Lift Bail Kit
4 Wheeled Undercarriage
Plastic Wire Cover for 50-60lb. Wire Packages
Deluxe Gas Regulator
Shielding Gas Hose
Ground Clamp
Weld Power Cables, Twist Mate to Lug
Welding Power Source
LF-72/74
Section BB-1
TABLE OF CONTENTS
- OPERATION SECTION -
Section BB-1
Operation..............................................................................................................Section BB
Recommended Processes and Required Equipment ...............................................BB-3
POWER FEED 10M SINGLE/DUAL
BB-2
SAFETY PRECAUTIONS
OPERATION
BB-2
GRAPHIC SYMBOLS THAT APPEAR ON
THIS MACHINE OR IN THIS MANUAL
Read this entire section of operating instructions before operating the machine.
COLD FEED
WARNING
POSITIVE OUTPUT
ELECTRIC SHOCK can kill.
• Unless using cold feed feature, when feeding with the gun trigger, the electrode and drive mechanism are always electrically energized and could remain energized several seconds after welding ceases.
• Do not touch electrically live parts or electrodes with your skin or wet clothing.
• Insulate yourself from the work and ground.
• Always wear dry insulating gloves.
-------------------------------------------------------------
ONLY QUALIFIED PERSONS SHOULD INSTALL,
USE OR SERVICE THIS EQUIPMENT. READ AND
FOLLOW THE MANUFACTURER’S INSTRUCTIONS,
EMPLOYER’S SAFETY PRACTICES AND MATERI-
AL SAFETY DATA SHEETS (MSDS) FOR CONSUM-
ABLES.
-----------------------------------------------------------
READ THIS WARNING, PROTECT YOURSELF &
OTHERS.
FUMES AND GASES can be dangerous.
• Keep your head out of fumes.
• Use ventilation or exhaust at the arc, or both, to keep fumes and gases from your breathing zone and general area.
NEGATIVE OUTPUT
PROTECTIVE
GROUND
WARNING OR
CAUTION
DANGEROUS
VOLTAGE
SHOCK
HAZARD
WELDING
FUMES
EXPLOSION
GAS INPUT
WELDING SPARKS can cause fire or explosion.
• Do not weld near flammable material.
• Do not weld on containers which have held flammable material.
ARC RAYS can burn.
• Wear eye, ear, and body protection.
WORK
CONNECTION
COMMON WELDING ABBREVIATIONS
WFS
• Wire Feed Speed
CV
• Constant Voltage
-----------------------------------------------------------
Observe additional guidelines detailed in the beginning of this manual.
GMAW (MIG)
• Gas Metal Arc Welding
FCAW (Innershield or Outershield)
• Flux Core Arc Welding
LF-72/74
BB-3
PRODUCT DESCRIPTION
OPERATION
General Physical Description
The LF-74 is optimized for GMAW and FCAW welding.
The powerful 4 roll MaxTrac™ drive, heavy duty enclosure and wire reel stand combine to make an easy to install, easy to use wire feeder for everyday welding.
Powering the wire drive is a high performance motor gearbox. A heavy duty hinged door opens easily, which provides an ample amount of room for assembling precision drive components and the welding gun.
RECOMMENDED PROCESSES
•
GMAW
•
FCAW
BB-3
General Functional Description
The LF-74 fulfills the need for an economical wire feeder with a high performance wire drive. Functional features included are those that offer the most value – a
WFS knob with a calibrated printed scale, cold-feed/ gas purge switch, trigger interlock switch and tachometer motor control.
MaxTrac™ technology delivers great feeding because:
• Patent pending drive rolls improve traction.
• The precision machined, rigid aluminum alloy frame results in maximum drive roll clamping pressure.
• Drive hubs with steel inner cores have 3 ball bearings inside each hub.
• The drive hubs are supported by large, heat treated and ground shafts for maximum rigidity and accurate drive roll alignment.
• Patent pending dual spring pressure arms have sensitivity for feeding soft wires without crushing them, and have plenty of compression force for feeding solid or stiff wires.
PROCESS LIMITATIONS
• The LF-74 is not recommended for GMAW-Pulse
Synergic, GTAW, GTAW-Pulse, CAG, SMAW
• The LF-74 is not compatible with push-pull equipment.
• For the heavy duty bench models K2426-2 and
K2426-3, the maximum spool size = 60 lb. (27.2 kg).
REQUIRED EQUIPMENT
Lincoln’s LF-74 is designed for use with the CV and DC family of power sources. These include:
• CV-250
• CV-300
• DC-400
• DC-600
• CV-305
• CV-400
• CV-655
• DC-655
• Invertec V350
Easy to configure, easy to service parts give
MaxTrac™ drives the edge in productivity.
• Patented split wire guides fully support the wire and virtually eliminate birdnesting.
• No tools required to change the drive rolls and wire guides.
• Changeable gun bushings easily accept guns from many manufacturers.
• Brass-to-brass connections between the electrode connection and the gun minimize voltage drop variations, resulting in consistent arc performance all day, every day.
OTHER COMPATIBLE POWER SOURCES
• Ranger 250
• Ranger 305
• Commander 300
• Vantage 300
• Vantage 500
• Air Vantage 500
Three models of the LF-74 are available to satisfy many customer set-ups:
• The base model is enhanced for GMAW welding with consumables from bulk packages or when a boom mounting is required.
• The bench model with heavy duty wire reel stand targets operators performing GMAW or FCAW welding using consumables on spools.
• The high torque model features high ratio gearing for feeding larger diameter FCAW or GMAW wires.
All models use a high performance motor-gear box with an integrated tachometer.
EQUIPMENT LIMITATIONS
• Maximum GMAW gun length = 25’ (7.6m)
• Maximum FCAW gun length = 15’ (4.6m)
• Maximum conduit length = 30' (9.1m)
• Maximum total control cable length = 100ft (31m)
• The LF-74 operates on 24-42VAC and not 115 VAC
• The K1733-1 and K1733-3 wire straighteners are not compatible with the LF-74
• Gun bushings are required for welding guns that do not have a Magnum (Tweco #2-#4 compatible) back end.
• The LF-74 does not attach to K303 or K377 wire reel stands.
LF-72/74
BB-4
OPERATION
FRONT PANEL CONTROLS AND CONNECTIONS
FIGURE BB.1 CASE FRONT CONTROLS
BB-4
1
2
3
4
5
6
7
8
ITEM
3
4
1
2
5
6
7
8
DESCRIPTION
Wire Feed Speed Knob.
Location for
Optional Remote Voltage Control (See Accessory Section For Kit Number).
Location for
Optional Burnback and Postflow Timer Kit (See Accessory Section For Kit Number).
Thermal LED, Motor Overload.
Cold Feed - Gas Purge Switch, press the switch up to feed wire with weld output off. Press the switch down for gas flow with weld output off.
2 step - Trigger Interlock switch.
Gun Receiver Bushing.
Trigger Connector 5-pin amphenol for connecting the MIG gun trigger. See Installation Section
for detail.
LF-72/74
BB-5
OPERATION
1. WIRE FEED SPEED KNOB
The large, calibrated wire feed speed knob makes for easy and accurate adjustment of the wire feed speed.
The knob rotates 3/4 turn. Turn the knob clockwise to increase the wire feed speed, and counter clockwise to reduce the wire feed speed.
BB-5
To set the burnback time, adjust the knob to approximately 0.03 seconds and then decrease or increase the time as desired.
K2426-1 and K2426-2 models:
These wire feeders are factory configured for normal speed operation.
The normal wire feed speed range is 100 to 800 in/min
(2.5 - 20.3 m/min).
K2426-3 model:
The wire feed speed range on the extra torque model is 50 to 400 in/min (1.3 – 10.2 m/min)
2. REMOTE VOLTAGE CONTROL KIT
The
optional remote voltage control kit adjusts the arc voltage from the minimum to the maximum voltage of the welding power source. Rotate the knob counterclockwise to reduce the arc voltage and rotate the knob clockwise to raise the arc voltage.
3. BURNBACK AND POSTFLOW TIMER KIT
The optional Burnback and Postflow Timer Kit gives control over the shielding gas at the end of the weld and prepares the end of the wire for the next arc start.
Additional shielding gas protection is often required when welding aluminum, stainless steel or exotic alloys.
When stitch welding, set the postflow time to maximum for best results.
Burnback Timer
The burnback timer range is OFF to 0.25 seconds.
The burnback timer controls the additional amount of time the power source output remains ON after the wire drive has stopped feeding wire. Burnback adjustment prevents the wire from sticking to the weld at the end of a weld and helps to condition the wire for the next weld.
Postflow Timer
The postflow timer range is OFF to 10 seconds.
Postflow is the time from when the power source output turns OFF until the postflow timer expires. Use postflow to protect the weld while the weld cools.
4. THERMAL LED, MOTOR OVERLOAD
The thermal light illuminates when the wire drive motor draws too much current. If the thermal light illuminates, the wire drive will automatically shutdown for up to 30 seconds to allow the motor to cool. To start welding again, release the gun trigger, inspect the gun cable, liner (and conduit). Clean and make repairs as necessary. Start welding again when the problem has been safely resolved.
For best results, keep the gun cable and conduit as straight as possible. Perform regular maintenance and cleaning on the gun liner, conduit and gun.
Always use quality electrode, such as L-50 or L-56 from Lincoln Electric.
5. COLD FEED/GAS PURGE SWITCH
Cold Feed and Gas Purge are combined into a single spring centered toggle switch.
To activate Cold Feeding, hold the switch in the UP position. The wire drive will feed electrode but neither the power source nor the gas solenoid will be energized.
Adjust the speed of cold feeding by rotating the WFS knob. Cold feeding, or "cold inching" the electrode is useful for threading the electrode through the gun.
Hold the toggle switch in the DOWN position to activate Gas Purge and let the shielding gas flow. The gas solenoid valve will energize but neither the power source output nor the drive motor will be turned on. The Gas Purge switch is useful for setting the proper flow rate of shielding gas. Flow meters should always be adjusted while the shielding gas is flowing.
LF-72/74
BB-6
6. 2 STEP - TRIGGER INTERLOCK
SWITCH
The 2 Step - Trigger Interlock switch changes the function of the gun trigger. 2
Step trigger operation turns welding on and off in direct response to the trigger.
Trigger Interlock operation allows welding to continue when the trigger is released for comfort on long welds.
OPERATION
Place the toggle switch in the DOWN position for 2
Step operation or in the UP position for Trigger
Interlock operation.
2 Step Trigger
BB-6
7. GUN RECEIVER BUSHING (K1500-2)
(K1500-2 bushing is standard on all LF-74's)
This Gun Receiver Bushing is used with Lincoln gun connectors, also with Magnum 200/300/400 guns and compatible with Tweco® #2-#4).
8. TRIGGER CONNECTOR 5-PIN AMPHENOL
This is used for connecting the MIG gun trigger. See
Installation Section for detail.
2 Step trigger operation is the most common. When the gun trigger is pulled, the welding power source energizes the electrode output and the wire feeder feeds wire for welding. The power source and wire feeder continue welding until the trigger is released.
Trigger Interlock
Trigger Interlock operation provides for operator comfort when making long welds. When the gun trigger is first pulled, the welding power source energizes the output and the wire feeder feeds wire for welding. The gun trigger is then released while the weld is made. To stop welding, the gun trigger is pulled again, and when it is released the welding power source output turns off and the wire feeder stops feeding wire.
CAUTION
• If the arc goes out while welding with trigger interlock operation, the electrode output from the welding power source remains energized and the wire feeder will continue to feed wire until the gun trigger is again pulled and then released.
------------------------------------------------------------------------
LF-72/74
Section CC-1
TABLE OF CONTENTS
- ACCESSORIES SECTION -
Section CC-1
Accessories .........................................................................................................Section CC
POWER FEED 10M SINGLE/DUAL
CC-2
ACCESSORIES
OPTIONAL KITS:
K2329-1 Remote Voltage Control Kit.
Includes: 10k potentiometer, harness, knob and decal with a 0-10 scale and mounting hardware.
K2330-1 Timer Kit.
Includes: Panel and harness for adjusting burnback and postflow times.
K2328-1
K2331-1
K2332-1
K1796-xx
K1803-1
K1840-xx
K1841-xx
K1842-xx
Standard Duty Wire Reel Stand.
Lift Bail Kit.
for use with K2328-1
Swivel Kit.
(for use with K2328-1 Standard
Duty Bench Models)
Includes: Wire Reel Stand for up to 44 lbs (20 kg) spools,
Spindle and mounting hardware.
Includes: Insulated lift bail and hardware.
Includes: Swivel adapter and mounting hardware for attaching to a power source lift bale.
Co-Axial Power Cable.
Work and Feeder Cables
Package.
Includes: Coaxial weld cable of length "xx". Ends of the weld cable have lug connections. Use for Pulse or STT welding.
Includes: Twist-Mate to Lug
2/0 cable 14' (1.2m) long with
Ground Clamp, and Twist-
Mate to Lug 2/0 Cable 9'
(2.7m) long.
Weld Power Cable, Twist-Mate to
Lug.
Includes: Twist-Mate to Lug,
1/0 cable of length "xx".
Weld Power Cable,
Twist-Mate to Twist-Mate.
Weld Power Cable, Lug to Lug.
Includes: Twist-Mate to Twist-
Mate, 1/0 Cable for 25' (7.6m) cables.
Includes: Twist-Mate to Twist-
Mate, 2/0 Cable for 50'
(15.2m) cables.
Includes: Lug to Lug, 3/0
Cable of length "xx" for lengths up to 60' (18.3m).
Lug to Lug, 4/0 Cable of length "xx" for lengths greater than 60' (18.3m).
LF-72/74
CC-2
CC-3
ACCESSORIES
OPTIONAL KITS:
K1797-xx
K2335-1
Control Cable.
Includes: 14 pin to 14 pin wire feeder to power source control cable.
Adapter for Miller Power Sources.
Includes: Adapter control cable for connecting a Lincoln
42 VAC wire feeder to a 24
VAC Miller power source.
K1520-1
K1798
K910-1
42 Volt Transformer Kit.
Adapter Cable for Control Cable to
Terminal Strip Power Sources.
Ground Clamp.
Includes: One transformer kit for operating a 42 VAC wire feeder on a power source supplying only 115 VAC.
Includes:
Includes: One 300 Amp
Ground Clamp.
K910-2 Ground Clamp.
Includes: One 500 Amp
Ground Clamp.
K1500-1
Gun Receiver Bushing (for guns with K466-1 Lincoln gun connectors; Innershield and Subarc guns.)
Includes: Gun receiver bushing, set screw and hex key wrench.
K1500-2
(standard on all
LF-74's)
Gun Receiver Bushing (for guns with
K466-2, K466-10 Lincoln gun connectors; Magnum 200/300/400 guns and compatible with Tweco® #2-#4.)
Includes: Gun receiver bushing with hose nipple, set screw and hex key wrench.
K1500-3
Gun Receiver Bushing (for guns with K613-7 Lincoln gun connectors; Magnum 550 guns and compatible with Tweco® #5.)
Includes: Gun receiver bushing with hose nipple, set screw and hex key wrench.
K1500-4
K1500-5
Gun Receiver Bushing (for gun with K466-3 Lincoln gun connectors; compatible with Miller® guns.)
Includes: Gun receiver bushing with hose nipple, set screw and hex key wrench.
Gun Receiver Bushing (compatible with Oxo® guns.)
Includes: Gun receiver bushing with hose nipple, 4 guide tubes, set screw and hex key wrench.
CC-3
LF-72/74
CC-4
ACCESSORIES
OPTIONAL KITS:
K489-7
K466-2
K613-7
K1546-1
K1546-2
K435
K468
K468-1
K363P
K438
K1504-1
Gun Receiver Bushing (for Lincoln
Fast-Mate guns.)
Includes: Gun receiver bushing with trigger connector.
Magnum 200/300/400 to K1500-2
Adapter.
Includes: Gun adapter, cotter pin, hex key wrench, wrench.
Magnum 550 to K1500-3 Adapter
Lincoln Conduit.
Includes: Trigger adapter, gun adapter and hex key wrench.
Incoming Bushing, for Lincoln
Conduit .025- 1/16" (0.6 - 1.6mm) wire.
Includes: Incoming bushing and hex key wrench.
Incoming Bushing, for Lincoln
Conduit 1/16-1/8" (1.6 - 3.2 mm ) wire.
Spindle Adapter, for mounting 14 lb. (6.4 kg) Innershield Coils on 2 in (51 mm) spindles.
Includes: Incoming bushing and hex key wrench.
Includes: Spindle Adapter made from 2 coil retainers.
(Electrode not included.)
Includes: Spindle Adapter.
Spindle Adapter, for mounting 8in
(203mm) diameter spools on 2 in
(51 mm) spindles.
Spindle Adapter, for mounting 2.5
in (64mm) diameter spools on 2 in
(51 mm) spindles.
Includes: Spindle Adapter.
Readi-Reel Adapter, for mounting
23-30 lb. (10.4 - 13.6 kg) reels to 2 in (51 mm) spindles.
Includes: Readi-Reel spool adapter. (Spool of electrode not included.)
Readi-Reel Adapter, for mounting
50-60 lb. (22.7 - 27.2 kg) reels to
2 in (51 mm) spindles. For use with Heavy Duty Bench models.
Includes: Readi-Reel spool adapter. (Spool of electrode not included.)
Coil Adapter, for mounting 50-60 lb. (22.7 - 27.2 kg) coils to 2 in (51 mm) spindles.
For use with heavy Duty Bench
Includes: 50-60 lb. (22.7 -
27.2 kg) coil adapter.
CC-4
LF-72/74
CC-5
ACCESSORIES
OPTIONAL KITS:
K1634-1
K1634-2
K659-1
3000290
K586-1
K1524-3
K163
K1557-1
K1556-1
Plastic Wire Cover for 30-44 lb.
(13.6 - 20.0 kg) Wire packages.
(For use with Standard Duty
Bench Models and Heavy Duty
Bench Models.)
Includes: Cover, backing plate, wire conduit, incoming bushing for .025 - 1/16" (0.6 -
1.6 mm) wire, incoming bushing for 1/16" - 1/8" (1.6 - 3.2
mm) wire, thumb screw, mounting hardware and hex key.
Plastic Wire Cover for up to 60 lb.
(27.2kg) Wire packages. (For use with Heavy Duty Bench Models.)
Gas Guard Regulator Includes: Gas Guard
Regulator and adjustment key.
Adjustable Gas Regulator
Deluxe Adjustable Gas Regulator
Includes: Gas Regulator for
Mixed Gases and 10' (3.0m)
Hose.
Includes: Deluxe Gas
Regulator for Mixed Gases,
Adapter for CO2 and 10'
(3.0m) Hose.
Includes: Heavy Duty Wire
Reel Stand.
Heavy Duty Universal Wire Reel
Stand. For spools up to 60 lb.
(27.2kg)
4 Wheeled Wire Feeder
Undercarriage (For use with
Standard Duty Bench Models and
Heavy Duty Bench Models.)
Includes: Undercarriage with
8" (203mm) rear wheels, 4"
(102mm)casters.
Swivel Platform (for use with
Heavy Duty Bench Models)
Includes: Swivel Platform and
Tray.
Light Duty Caster Kit (for use with
Heavy Duty Bench Models)
Includes: 2 Swivel Casters, 2
Fixed Casters, brackets and mounting hardware.
K1555-1
Insulated Lift Bail
(for use with Heavy Duty Bench
Models)
Includes: Insulated Lift Bail and mounting hardware.
CC-5
LF-72/74
CC-6
NOTES
CC-6
LF-72/74
Section DD-1
TABLE OF CONTENTS
- MAINTENANCE SECTION -
Section DD-1
Maintenance ........................................................................................................Section DD
POWER FEED 10M SINGLE/DUAL
DD-2
MAINTENANCE
Safety Precautions
WARNING
ELECTRIC SHOCK can kill.
MAINTENANCE
DD-2
Calibration of the LF-74 may be required when the p.c.
board, potentiometer or motor is replaced or serviced.
Calibration matches the scale on the name plate to the actual wire feed speed.
• Do not touch electrically live parts such as output terminals or internal wiring.
To verify the wire feed speed,
1. Assemble a .045 (1.2 mm) drive roll kit to the feeder.
2. Load .045 (1.2 mm) steel wire into the feeder.
3. Trim the wire to the end of the contact tip of the gun.
4. Adjust the WFS knob per the Table D.1.
TABLE D.1
• When inching with gun trigger, electrode and drive mechanism are “hot” to work and ground and could remain energized several seconds after the gun trigger is released.
• Turn OFF input power at welding power source before installation or changing drive roll and/or guide tubes.
• Welding power source must be connected to system ground per the National Electrical Code or any applicable local codes.
• Only qualified personnel should perform maintenance work.
------------------------------------------------------------------------
Observe all additional Safety Guidelines detailed throughout this manual.
ROUTINE MAINTENANCE
• Clean and tighten all weld terminals.
• Inspect all weld cables, control cables, gun cables and shielding gas hoses. Repair or replace as necessary.
To calibrate the wire feed speed,
Tools required:
• 5/16" nut driver
• 3/4" open end wrench
• WFS meter or RPM meter
• Shorting plug. The shorting plug shorts pins 1 and 5 of connector J2 on the p.c. board. J2 is a 6 pin molex.
PERIODIC MAINTENANCE
•
Clean drive roll grooves.
• Blow out or vacuum the inside of the feeder.
MODEL
K2426-1, K2426-1
K2426-3
WFS knob setting
400
200
5. Activate and hold the COLD FEED switch for 10 seconds.
6. Measure the length of wire extending from the contact tip. The wire length shown in Table D.2.
TABLE D.2
MODEL
K2426-1, K2426-1
K2426-3
WIRE LENGTH
50 inches ± 5 inches (1270 mm ± 127mm)
25 inches ± 2.5 inches (635 mm ± 64 mm)
CALIBRATION SPECIFICATION
WARNING
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts.
• When inching with the gun trigger, electrode, wire drive motor and drive mechanism are "hot" to work and ground and could remain energized several seconds after the gun trigger is released.
• Welding power source must be connected to system ground per the National Electrical Code or any applicable local codes.
• Only qualified personnel should perform maintenance work.
------------------------------------------------------------------------
1. Turn off power to the LF-74 and welding power source.
2. Disconnect the electrode lead from the feed plate and from the welding power source.
3. Remove the wraparound from the LF-74,
See
4. Turn on power to the LF-74 and welding power source.
5. Adjust the WFS knob per the Table D.1.
6. Insert the shorting plug into the control p.c. board J2.
7. Wait a minimum of 1 second.
8. Remove the shorting plug.
9. Connect J2 of the harness to p.c. board.
10. Turn off power to the LF-74 and welding power source.
11. Assemble the wraparound.
12. Connect the electrode lead.
LF-72/74
DD-3
MAINTENANCE
FIGURE DD.1
DD-3
FIGURE DD.2
LF-72/74
J2 CONNECTOR
DD-4
1. Center Assembly
2. Wire Drive Assembly
3. Wire Reel Stand LF-72
4. Wire Reel Stand LF-74
MAINTENANCE
DD-4
2
FIGURE DD.3 - MAJOR COMPONENT LOCATION
3
4
1
LF-72/74
Section E-1
TABLE OF CONTENTS
- THEORY OF OPERATION SECTION -
Section E-1
Theory of Operation ...............................................................................................Section E
14 PIN
INPUT CABLE
RECEPTACLE
24/42 VAC
FIGURE E.1 – LF-72/74 BLOCK LOGIC DIAGRAM
OPTIONAL
BURNBACK
TIMER
OPTIONAL
REMOTE
VOLTAGE
CONTROL
GAS
SOLENOID
3.75 AMP
OVERLOAD
PROTECTION
WIRE DRIVE
RECEPTACLE
WIRE
DRIVE
MOTOR
TACK
To Gun Trigger
CONTROL BOARD
COLD FEED
GAS PURGE
WIRE FEED
SPEED POT.
TRIGGER
INTERLOCK
2-STEP
LF-72/74 SINGLE/DUAL
E-2
THEORY OF OPERATION
FIGURE E.2
GENERAL DESCRIPTION & INPUT RECEPTACLE, CONTROL BOARD AND OPERATOR CONTROLS
E-2
OPTIONAL
BURNBACK
TIMER
OPTIONAL
REMOTE
VOLTAGE
CONTROL
GAS
SOLENOID
3.75 AMP
OVERLOAD
PROTECTION
WIRE DRIVE
RECEPTACLE
WIRE
DRIVE
MOTOR
TACK
To Gun Trigger
14 PIN
INPUT CABLE
RECEPTACLE
24/42 VAC
CONTROL BOARD
COLD FEED
GAS PURGE
GENERAL DESCRIPTION
WIRE FEED
SPEED POT.
The LF72 and LF74 are single head, 24vac or 42vac input, 2 roll (LF72) or 4 roll (LF74) wire feeders. They have a single calibrated control for wire feed speed
WFS and an optional K2339-1 remote voltage control kit to be used in conjunction with a Lincoln constant voltage (CV) direct current DC power source.
The LF72 and LF74 offer the user 3 individual features
Cold feed, trigger interlock 2 step trigger control and gas purge. Presettable burnback and postflow timers are also available with an optional K2330-1 timer kit.
The motor is equipped with a 3.75amp current overdraw protection circuit, which is indicated by a THER-
MAL LED located on the case front.
TRIGGER
INTERLOCK
2-STEP
INPUT RECEPTACLE, CONTROL
BOARD AND OPERATOR CON-
TROLS
The 24 or 42-volt input is applied to the LF72 or LF74 through the 14 pin amphenol type connector. The remote trigger leads are accessed through 14 pin receptacle. The input voltage is rectified by a full wave bridge and is sent to a switching power supply in the control board where it is filtered. This filtered DC voltage is applied to a switching power supply. The switching power supply manufactures +15vdc and
+5vdc regulated supplies for the control board circuitry.
The control board receives commands from the user operated controls for the wire feed speed WFS pot, the optional timer kit and the optional voltage remote control kit. It compares this feedback information with the user command signals and generates appropriate signals to control wire feed speed, arc voltage and gas flow.
The control board is also responsible for the operation of the trigger interlock, 2-step, cold feed and the gas purge features of the LF72 and the LF74.
LF-72/74 SINGLE/DUAL
E-3
14 PIN
INPUT CABLE
RECEPTACLE
24/42 VAC
THEORY OF OPERATION
FIGURE E.3 – DRIVE MOTOR, TACH FEEDBACK AND GAS SOLENOID
OPTIONAL
BURNBACK
TIMER
OPTIONAL
REMOTE
VOLTAGE
CONTROL
GAS
SOLENOID
3.75 AMP
OVERLOAD
PROTECTION
WIRE DRIVE
RECEPTACLE
WIRE
DRIVE
MOTOR
TACK
To Gun Trigger
E-3
CONTROL BOARD
COLD FEED
GAS PURGE
WIRE FEED
SPEED POT.
DRIVE MOTOR, TACH FEEDBACK
AND GAS SOLENOID
The leads to the drive motor, gas solenoid and the tach (hall effect device LF-74 and LF-72 above codes
11290) are brought into the control box via the 14 pin receptacle. This 14 pin receptacle also houses the gun trigger leads and the voltage sense leads. When the gun trigger is activated the control board energizes the gas solenoid, the wire drive motor and the welding power source. The control board receives a tach feedback signal and adjusts the motor armature voltage to match the preset wire feed speed.
The control board also monitors the drive motor amperage and will shut down the wire drive for 30 to
60 seconds to allow the motor to cool if the amperage exceeds 3.75 amps for an extended time.
TRIGGER
INTERLOCK
2-STEP
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
LF-72/74
E-4
NOTES
E-4
LF-72/74
Section F-1
TABLE OF CONTENTS
- TROUBLESHOOTING & REPAIR SECTION -
Section F-1
Troubleshooting & Repair Section ........................................................................Section F
PC Board Troubleshooting Procedures and Replacement...........................................F-3
Test Procedures
Replacement Procedures
PC Board Removal and Replacement.........................................................F-15/F-16
Wire Drive Motor and Gear Box Removal and Replacement......................F-17/F-20
LF-72/74 SINGLE/DUAL
F-2
TROUBLESHOOTING & REPAIR
HOW TO USE TROUBLESHOOTING GUIDE
CAUTION
Service and repair should be performed by only Lincoln Electric Factory Trained Personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician and machine operator and will invalidate your factory warranty. For your safety and to avoid Electrical Shock, please observe all safety notes and precautions detailed throughout this manual.
F-2
This Troubleshooting Guide is provided to help you locate and repair possible machine malfunctions. Simply follow the three-step procedure listed below.
Step 1. LOCATE PROBLEM (SYMPTOM). Look under the column labeled “PROBLEM
(SYMPTOMS)”. This column describes possible symptoms that the machine may exhibit. Find the listing that best describes the symptom that the machine is exhibiting. Symptoms are grouped into three main categories: Feeding
Problems and Welding Problems.
Step 3. PERFORM COMPONENT TESTS. The last column, labeled “Recommended Course of
Action” lists the most likely components that may have failed in your machine. It also specifies the appropriate test procedure to verify that the subject component is either good or bad. If there are a number of possible components, check the components in the order listed to eliminate one possibility at a time until you locate the cause of your problem.
Step 2. PERFORM EXTERNAL TESTS. The second column, labeled “POSSIBLE AREAS OF
MISADJUSTMENT(S)”, lists the obvious external possibilities that may contribute to the machine symptom. Perform these tests/checks in the order listed. In general, these tests can be conducted without removing the case wrap-around cover.
All of the referenced test procedures referred to in the Troubleshooting Guide are described in detail at the end of this chapter. Refer to the
Troubleshooting and Repair Table of Contents to locate each specific Test Procedure. All of the referred to test points, components, terminal strips, etc., can be found on the referenced electrical wiring diagrams and schematics. Refer to the Electrical Diagrams Section Table of
Contents to locate the appropriate diagram.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.
LF-72/74
F-3
TROUBLESHOOTING & REPAIR
PC BOARD TROUBLESHOOTING PROCEDURES
WARNING
ELECTRIC SHOCK can kill.
• Have an electrician install and service this equipment. Turn the input power OFF at the fuse box before working on equipment. Do not touch electrically hot parts.
CAUTION
Sometimes machine failures appear to be due to PC board failures. These problems can sometimes be traced to poor electrical connections. To avoid problems when troubleshooting and replacing PC boards, please use the following procedure:
1. Determine to the best of your technical ability that the PC board is the most likely component causing the failure symptom.
2. Check for loose connections at the PC board to assure that the PC board is properly connected.
3. If the problem persists, replace the suspect PC board using standard practices to avoid static electrical damage and electrical shock. Read the warning inside the static resistant bag and perform the following procedures:
PC board can be damaged by static electricity.
ATTENTION
Static-Sensitive
Devices
Handle only at
Static-Safe
Workstations
- Remove your body’s static charge before opening the staticshielding bag. Wear an anti-static wrist strap. For safety, use a 1
Meg ohm resistive cord connected to a grounded part of the equipment frame.
- If you don’t have a wrist strap, touch an un-painted, grounded, part of the equipment frame. Keep touching the frame to prevent static build-up. Be sure not to touch any electrically live parts at the same time.
F-3
- Remove the PC board from the static-shielding bag and place it directly into the equipment. Don’t set the
PC board on or near paper, plastic or cloth which could have a static charge. If the PC board can’t be installed immediately, put it back in the static-shielding bag.
- If the PC board uses protective shorting jumpers, don’t remove them until installation is complete.
- If you return a PC board to The Lincoln Electric
Company for credit, it must be in the static-shielding bag. This will prevent further damage and allow proper failure analysis.
4. Test the machine to determine if the failure symptom has been corrected by the replacement PC board.
NOTE: It is desirable to have a spare (known good)
PC board available for PC board troubleshooting.
NOTE: Allow the machine to heat up so that all electrical components can reach their operating temperature.
5. Remove the replacement PC board and substitute it with the original PC board to recreate the original problem.
a. If the original problem does not reappear by substituting the original board, then the PC board was not the problem. Continue to look for bad connections in the control wiring harness, junction blocks, and terminal strips.
b. If the original problem is recreated by the substitution of the original board, then the PC board was the problem. Reinstall the replacement PC board and test the machine.
6. Always indicate that this procedure was followed when warranty reports are to be submitted.
NOTE: Following this procedure and writing on the warranty report, “INSTALLED AND SWITCHED PC
BOARDS TO VERIFY PROBLEM,” will help avoid denial of legitimate PC board warranty claims.
- Tools which come in contact with the PC board must be either conductive, anti-static or static-dissipative.
LF-72/74
F-4
LF-72/74
TROUBLESHOOTING & REPAIR
F-4
PROBLEMS
(SYMPTOMS)
Observe Safety Guidelines detailed in the beginning of this manual.
POSSIBLE AREAS OF
MISADJUSTMENT(S)
FUNCTION PROBLEMS
RECOMMENDED
COURSE OF ACTION
The wire drive does not feed wire and the drive rolls do not spin
The wire feeds erratically, or the motor LED lights.
1. Power source not on
2. Possible tripped breaker
3. Faulty gun trigger
4. Possible faulty control cable
1. Wrong drive rolls installed.
2. Possible problem with gun
1. Verify the power source is on
Verify power is being applied to the wire feeder
2. Verify the circuit breaker of the wire feeder or the power source has not tripped
3. Check to see if the gun trigger is working properly
4. Check for cable continuity, and for broken or bent pins.
1. Verify the correct drive rolls and inner wire guides are installed in the wire drive
The wire continues to feed when the gun trigger is released.
3. Pressure arm or brake tension to tight.
2. Check for sharp bends in gun liner
4. Examine the contact tip for wear or proper size
Check gun liner. The welding electrode should slide easily through the gun. Verify proper gun liner is installed
1. Trigger interlock switch in wrong position.
2. Gun trigger shorted or stuck
3. Adjust brake tension. Adjust
4. Replace if necessary
5. If using wire conduit, verify that the wire slides easily through the conduit.
1. Check if the 2 step/ trigger interlock switch is in the TRIGGER
INTERLOCK position.
2. Verify operation of the gun trigger. Check for shorted trigger leads.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department at 1-888-935-3877 for electrical troubleshooting assistance before you proceed.
LF-72/74 SINGLE/DUAL
F-5
TROUBLESHOOTING & REPAIR
F-5
LF-72/74
PROBLEMS
(SYMPTOMS)
Observe Safety Guidelines detailed in the beginning of this manual.
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
No shielding gas.
Variable or hunting arc.
When the trigger is pulled, the drive rolls spin but no arc voltage
FUNCTION PROBLEMS (Continued)
1. No gas supply, or gas supply interrupted.
2. Solenoid not functioning.
1. Bad contact tip
2. Possible loose connection in current carrying cables.
3. Set up not correct.
4. Problem with shielding gas.
1. Possible bad gun or faulty connections in the heavy current carrying leads.
2. Possible faulty control cable.
1. Verify cylinder is not empty and is turned on.
Check the hose for cuts or kinks.
Make sure it is not crushed.
Verify the hose is connected to the gun bushing or welding gun.
1. Check for proper size contact tip. Make sure tip is not worn, and is free of spatter.
2. Clean and tighten all electrode and work connections. Verify the gun bushing is tightly mounted to the wire drive.
Verify the gun is tightly mounted to the gun bushing.
3. Verify the proper polarity is being used for the weld procedure. Make sure the proper electrode stick-out is being maintained.
4. Check the gas flow rate and mixture.
5. Control board may be faulty.
1. Check all electrode and work connections. Verify the the gun bushing is tight to the wire drive. Verify gun is tightly mounted to the bushing.
3. Possible defective power source.
2. Check the control cable and connectors for continuity, cuts, or broken pins.
3. Verify the power source is operating properly.
The arc burns back to the tip.
The gas continues to flow for a long time after the weld.
1. If timer kit is installed, reduce the amount of burnback time.
2. If the timer kit is installed, reduce the amount of post flow time.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department at 1-888-935-3877 for electrical troubleshooting assistance before you proceed.
LF-72/74 SINGLE/DUAL
F-6
LF-72/74
TROUBLESHOOTING & REPAIR
F-6
PROBLEMS
(SYMPTOMS)
Observe Safety Guidelines detailed in the beginning of this manual.
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
FUNCTION PROBLEMS (Continued)
The motor (L12081) failed when a load (6 N m) was applied to the wire drive.
When testing the wire drives for feeding problems (“inconsistent feeding”, “grinding noises from the gearbox”, “jumping drive rolls”) the wire drive should be tested under load.
This can be done by loading a spool of wire, setting the spindle brake to maximum and hen feeding wire.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department at 1-888-935-3877 for electrical troubleshooting assistance before you proceed.
LF-72/74
F-7
TROUBLESHOOTING & REPAIR
DRIVE MOTOR AND TACH FEEDBACK TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test / repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
TEST DESCRIPTION
This test will help determine if the wire drive motor is receiving the correct voltage and is capable of running properly. It will also determine if the tach sensor is receiving the correct input from the control board, and is sending back the correct signal.
MATERIALS NEEDED
5/16 in. nut driver
32 VDC @ 1 amp variable power source
Volt-Ohm Meter
F-7
LF-72/74
F-8
TROUBLESHOOTING & REPAIR
F-8
MOTOR AND TACH FEEDBACK TEST (continued)
TEST PROCEDURE
1. Remove power from the LF72/LF74 wire drive unit.
6. Check for between 1 and 2 ohms of resistance between the above mentioned leads. Also make sure there is at least 500k ohms of resistance between both leads and the motor shell.
2. Using a 5/16 nut driver remove the 5 screws holding the case.
3. Locate the two motor leads and the tach leads See
Figure F.1.
7. With the trigger activated and the motor running check for 5VDC input on the black and red tach leads. Check for .7 VDC to .85 VDC on the black and blue return leads.
4. Apply the correct input voltage (42VAC) to the unit.
8. For further testing on the drive motor you can use an isolated power source and apply between 1 and
31VDC to the leads.
5. With the trigger activated and the motor running check for 1VDC min. (210HZ) to 31VDC
(1.75KHZ)max. between the black and white motor leads (pins 7 and 8).
9. If the armature voltage is not present (step 5) and the motor operates normally when an isolated power source is applied (step 8) Control board may be faulty.
FIGURE F.1 – TACH LEAD LOCATION
TACH
BLACK
BLACK
LEAD
WHITE
LEAD
5
1
6
7
23
8
4
TACH
RED
TACH
BLUE
LF-72/74
F-9
TROUBLESHOOTING AND REPAIR
GAS SOLENOID TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test / repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
TEST DESCRIPTION
This test will determine if the gas solenoid is receiving the correct voltage and if the solenoid is functional.
F-9
MATERIALS NEEDED
5/16 in. nut driver
12 VDC @ 1 amp power source
Volt-Ohmmeter
LF-72/74
F-10
TROUBLESHOOTING AND REPAIR
GAS SOLENOID TEST
(continued)
FIGURE F.2 - GAS SOLENOID FIGURE F.3 – LEADS 552, 552B & 553
F-10
GAS SOLENOID
Coil measures
21 ohms
Located on case back
GAS
SOLENOID
Off = 0 VDC
OCV = 59 VDC
On = 7.7 VDC
553
552
552B
TEST PROCEDURE
1. Remove the input power from the
LF72/LF74 unit.
6. If the 8VDC is missing or low, check the leads and connections between the solenoid and the control board.
See the wiring diagram. If the leads and connections are ok, the control board may be faulty.
2. Using the 5/16 nut driver, remove the
5 screws holding the cover.
7. Normal solenoid coil resistance is 21 ohms.
3. Locate the gas solenoid (FIG F.2) on the back of the feeder.
4. Apply the correct (42VAC) input voltage to the unit.
8. The solenoid can be further checked by disconnecting the leads and applying 12VDC directly to the terminals. If the solenoid does not activate the solenoid is faulty.
5. While pressing the gas purge button or activating the gun trigger, check for approximately 8VDC at the solenoid leads (FIG F.3). If the 8VDC is present the solenoid should activate.
If the 8VDC is present but the solenoid does not activate the solenoid may be faulty.
9. Reconnect the leads and replace the cover.
LF-72/74
F-11
TROUBLESHOOTING AND REPAIR
DIODE BRIDGE TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test / repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
TEST DESCRIPTION
This test will help determine if the diode bridge is receiving the power AC input voltages and is converting them to the correct DC output voltages.
MATERIALS NEEDED
5/16 in. nut driver
42VAC power supply
Volt-Ohmmeter
F-11
LF-72/74
F-12
41
TROUBLESHOOTING AND REPAIR
DIODE BRIDGE TEST
(continued)
FIGURE F.4 – CONTACTOR
552B
+
552A
F-12
-
580
42
TEST PROCEDURE
1. Remove the input power from the unit.
2. Using a 5/16 nut driver remove the 5 screws holding the cover.
3. Apply the correct input voltage
(42VAC) to the LF72/LF74 unit.
4. Check for the correct input voltage at leads 41 and 42 on the bridge. If the input voltage is not there check the wiring back to the receptacle assembly pins I and K.
5. Check for the proper output on leads
580 negative and 522 positive. The voltage should be 59VDC. If you are only reading 38VDC the control circuit is open. Check the wiring and the connections back to your control board.
LF-72/74
F-13
TROUBLESHOOTING AND REPAIR
WIRE SPEED POTENTIOMETER TEST
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test / repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
TEST DESCRIPTION
This test will help determine if the wire speed potentiometer is receiving and sending the correct voltages..
MATERIALS NEEDED
5/16 in. nut driver
42VAC power supply
Volt-Ohmmeter
F-13
LF-72/74
F-14
TROUBLESHOOTING AND REPAIR
WIRE SPEED POTENTIOMETER TEST (Continued)
Figure F.5
F-14
577
576
575
0 VDC MIN. WFS
5 VDC MIN. WFS
10K/2W
WIRE FEED
SPEED
CONTROL
POTENTIOMETER
TEST PROCEDURE
1. Remove the input power from the unit.
2. Using 5/16 nut driver remove the 5 screws holding the cover.
3. Apply the correct input voltage
(42VAC) to the LF72/LF74 unit.
4. Locate the P8 plug (see wiring diagram) going to the potentiometer.
5. Check for 0VDC minimum to 5VDC maximum between wires 575 and 576.
If the voltage is not there, check the wires for continuity back to the control board. If the wiring checks out good, the control board may be faulty.
6. The potentiometer can also be checked by unplugging the P8 connection (see wiring diagram), and checking for 0 to 10k ohms between leads 575 and 576 (as pot is located).
7. Reconnect the disconnected leads and reassemble the cover.
LF-72/74
F-15
TROUBLESHOOTING AND REPAIR
PC BOARD REMOVAL AND REPLACEMENT
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test / repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
TEST DESCRIPTION
This procedure will aid the technician in the removal and replacement of the control pc board.
MATERIALS NEEDED
5/16 in. nut driver
3/8 in. nut driver
Anti-static strap
F-15
LF-72/74
F-16
TROUBLESHOOTING AND REPAIR
F-16
CONTROL PC BOARD REMOVAL AND REPLACEMENT PROCEDURE
(Continued)
Figure F.6 - PC Board Location
CONTROL BOARD
REMOVAL PROCEDURE
1. Remove the input power ( 42VAC ) from the LN72/LN74 unit.
2. Using the 5/16 nut driver remove the 5 screws holding the cover.
3. Locate the control board (see figure F.6) and remove the harness plugs on the control board. Observe static electricity precautions.
4. Remove the 4 nuts holding the board using the 3/8 inch nut driver, and remove the board.
REPLACEMENT PROCEDURE
1. Remove the new control board from the static bag and place it on the 4 studs.
2. Reassemble the 4 nuts and tighten hand tight.
3. Reassemble the harness plugs.
4. Reassemble the case.
LF-72/74
F-17
TROUBLESHOOTING AND REPAIR
WIRE DRIVE MOTOR AND GEAR BOX
REMOVAL AND REPLACEMENT PROCEDURE
WARNING
Service and repair should be performed by only Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in danger to the technician or machine operator and will invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety notes and precautions detailed throughout this manual.
If for any reason you do not understand the test procedures or are unable to perform the test / repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
TEST DESCRIPTION
This procedure will aid the technician in the removal and replacement of either the drive motor or the gear box.
MATERIALS NEEDED
5/16 in. nut driver
7/16 in. socket wrench and extension
3/4 in. wrench
Phillips head screw driver
Pliers
F-17
LF-72/74
F-18
TROUBLESHOOTING AND REPAIR
F-18
WIRE DRIVE MOTOR AND GEAR BOX REMOVAL AND REPLACEMENT
PROCEDURE (Continued)
Figure F.7 - Wire Drive Motor(s)
MOUNTING SCREWS *
SECURING WIRE DRIVE PANEL
MOUNTING SCREWS*
SECURING WIRE DRIVE PANEL
*REMOVE 6 MOUNTING SCREWS
INCOMING
BUSHING
BALL
BUSHING
ASSEMBLY
O-RING
SET SCREW
MOUNTING BOLTS
PROCEDURE
1. Remove th input power from the
LF72/LF72 unit.
2. Remove the gun from the unit.
3. Using the 5/16 nut driver remove the 5 screws holding the cover.
4. Using the Phillips head screw driver remove the #67 electrode sense lead from the connection block.
5. Using the pliers remove the gas hose from the connection block. Be careful not to damage the hose.
6. Using the 3/4 inch wrench remove the electrode cable from the connector block.
7. Remove the tach and motor leads by disconnecting the P10 connector. See wiring diagram.
8. Using the 7/16 inch socket wrench and extension remove the six mounting bolts. See figure F.7. The motor, and gear box assembly can now be removed from the LF72/LF74 unit.
LF-72/74
F-19
TROUBLESHOOTING AND REPAIR
F-19
WIRE DRIVE MOTOR AND GEAR BOX REMOVAL AND REPLACEMENT
PROCEDURE (Continued)
REMOVAL OF THE DRIVE
MOTOR FROM THE GEAR BOX
REMOVAL OF THE GEAR BOX
FROM THE MOUNTING PANEL.
1. Using the 7/16 in. wrench remove the
note the LF72 only has one screw.
2. Loosen and remove the outer wire guide.
3. Loosen and remove the drive roll assembly. The LF72 has one while the
LF74 has three.
4. Using the Phillips head screw driver
5. Using the phillips head screw driver remove the three screws holding the drive motor.
6. Follow the first five steps found in the drive motor removal.
7. Using the 7/16 wrench remove the four bolts holding the gear box to the panel.
LF-72/74
F-20
TROUBLESHOOTING AND REPAIR
F-20
WIRE DRIVE MOTOR AND GEAR BOX REMOVAL AND REPLACEMENT
PROCEDURE (Continued)
REPLACEMENT PROCEDURES
1. Line up the gear box with the 4 holes on the panel. Replace and tighten the four
1/4-20 x 1/2 in. hex head bolts.
2. Insert the drive motor through the panel and gear box. Line up and tighten the three M6 x 1.00 in. Phillips pan head screws.
3. Replace the drive gear and secure in place using the screw and lock washer previously removed.
4. Replace the drive rolls and secure the secure locking rings.
5. Replace the gear box cover and secure with the 1/4-20 hex head screws.
6. Feed the gas hose, and the # 67 lead through the notch on the panel. Feed the
P10 plug through the center panel. Align and mount and tighten the panel using the six lock washers and bolts previously removed.
7. Plug the P10 plug into the wiring harness.
8. Using the Phillips head screw driver connect the #67 electrode sense lead to the connector block.
9. Using the 3/4 in. wrench connect the electrode lead to the connector block.
10. Connect the gas hose.
11. Install the cover using the five screws.
12. Connect the gun.
LF-72/74
F-21
TROUBLESHOOTING AND REPAIR
RETEST AFTER REPAIR
F-21
Retest a machine:
• If it is rejected under test for any reason that requires you to remove any part which could affect the machine’s electrical characteristics.
OR
• If you repair or replace any electrical components.
SET UP
1. Connect a supply of filtered compressed air at 80 psi to the gas inlet.
2. Supply 42VAC to the machine.
3. Connect the gun to the connector block.
OPERATION VERIFICATION
1. Close the idle arms and the pressure arms.
2. Activate the cold feed switch.
3. Verify the drive rolls are spinning in the forward direction.
4. Adjust the wire speed knob from min to max and verify the speed is changing.
5. Release the cold feed switch and verify that the drive rolls stop abruptly.
6. Activate the gas purge switch and verify that there is gas flow.
7. Release the gas purge switch and verify the gas flow stops.
8. Place the 2-step/trigger interlock switch in the trigger interlock position.
9. Activate the gun trigger and verify the drive rolls spin.
10. Release the gun trigger and verify the drive rolls continue to spin.
11. Activate and release the gun trigger and verify the drive rolls stop abruptly.
12. Place the 2-step/trigger interlock switch in the 2-step position.
LF-72/74
F-22
NOTES
F-22
LF-72/74
Section G-1
TABLE OF CONTENTS
- ELECTRICAL DIAGRAMS SECTION -
Section G-1
Electrical Diagrams........................................................................................................................Section G
Wiring Diagram - Entire Machine - Code 11209, 11210, 11211, 11227 - (L12146-1) LF-72 ............G-3
Wiring Diagram - Entire Machine - Code 11290, 11291, 11292, 11293 - (L12146-2) LF-72 ............G-4
LF-72/74
G-2
WIRING DIAGRAM - ENTIRE MACHINE - CODE 11075, 11076, 11077 (L12146) LF-72
ELECTRICAL DIAGRAMS
CAVITY NUMBERING SEQUENCE
(COMPONENT SIDE OF P.C. BOARD)
1
J3
2
J5,J8
J9,J60
1
5
J7
1 2
3 4
4
J1,J14
8
1
9
J2
1
4
3
6
8
16
COLOR CODE
B -
W -
R -
U -
BLACK
WHITE
RED
BLUE
N.B.
575
576
577
1
5
6
2
3
4
P8
575A
576A
577A
577A
576A
575A
3
2
1
10K/2W
N.C.
WIRE FEED
SPEED
CONTROL
POTENTIOMETER
552B
552
75A
76A
77A 3
4
1
2
P7
75
76
77
77
76
75
3
2
1
10K/2W
REMOTE
CONTROL
VOLTAGE
POTENTIOMETER
(OPTIONAL)
L2
67
FEED
PLATE
INPUT ELECTRODE
CABLE CONNECTION
N.B.
N.C.
GAS
SOLENOID
553
42VAC
14 PIN
AMPHENOL
CONNECTOR
TO POWER
SOURCE
ARC VOLTAGE
SENSE
J6
L
M
J
K
H
I
F
G
N
A
B
C
D
E
41
50
42
51
2
4
77A
76A
75A
67
N.B.
L1
41A
41
BAFFLE
MOUNTED
RECTIFIER
DIODE
BRIDGE
552B
552A
552C
-
580
42
575
575B
575C
L4 L5
563
562
575B
551
550
7
8
5
6
1
2
3
4
P5
W
B
N.B.
TACH
R
U
B
MOTOR /
GEARBOX
B W
562
580
577
554
550
552A
575C
553 556
551
576
563
552
COMMON ANALOG P.C. BOARD
4 2
587 608
605 607 W
K
E
Y
558
559
601 589
515
606
P9
1 2 3 4 5 6 7 8 9 10
50 41A 51 552C
POST-FLOW
L3
J60
1 2 3 4 5 6 7 8
601 515A 605 607
606A
608
BURNBACK
606A
B
606
TIMER KIT
(OPTIONAL)
N.A.
556
554
C
D
E
A
B
TRIGGER
INPUT
TRIGGER
CONNECTOR
J4
N.D.
N.B.
W
THERMAL LED
B
COLD FEED
N.C.
558
515A
515
559
GAS PURGE
S1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 4 5 6 1 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
TRIGGER
INTERLOCK
J1 J2 J3 J14
589
587
S2
N.A.
N.C.
2-STEP
NOTES:
N.A. CAVITY NUMBERING SEQUENCE AS VIEWED FROMCOMPONENT SIDE OF BOARD.
N.B. CAVITY NUMBERING SEQUENCE AS VIEWED FROM LEAD SIDE OF CONNECTOR.
N.C. TOGGLESWITCHES AND POTENTIOMETERS SHOWN FROMCONNECTION SIDE OF SWITCH.
N.D. PIN NEAREST THE FLAT EDGE OF LED LENS ALIGNS WITH WHITE LEAD OF LED SOCKET.
A
L12146
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine.
G-2
LF-72/74
G-3
ELECTRICAL DIAGRAMS
WIRING DIAGRAM - ENTIRE MACHINE - CODE 11209, 11210, 11211,11227 (L12146-1) LF-72
CAVITY NUMBERING SEQUENCE
(COMPONENT SIDE OF P.C. BOARD)
1
J3
2
J5,J8
J9,J60
1
5
J7
3
1
2
4
4
J1,J14
8
1
9
J2
1
4
3
6
8
16
COLOR CODE
B -
W -
R -
U -
BLACK
WHITE
RED
BLUE
N.B.
575
576
577
1
2
3
4
5
6
P8
575A
576A
577A
577A
576A
575A
3
2
1
10K/2W
N.C.
WIRE FEED
SPEED
CONTROL
POTENTIOMETER
552B
552
75A
76A
77A
1
2
3
4
P7
75
76
77
77
76
75
3
2
1
10K/2W
N.C.
REMOTE
CONTROL
VOLTAGE
POTENTIOMETER
(OPTIONAL)
L2
67
FEED
PLATE
INPUT ELECTRODE
CABLE CONNECTION
N.B.
GAS
SOLENOID
553
41
42VAC
14 PIN
AMPHENOL
CONNECTOR
TO POWER
SOURCE
M
N
K
L
I
J
G
H
E
F
C
D
A
B
SENSE
J6
2
4
77A
76A
75A
41
42
67
N.B.
L1
BAFFLE
MOUNTED
RECTIFIER
DIODE
BRIDGE
552B
552A
-
580 42
575
575B
575C
L4
L5
563
562
575B
551
550
1
2
3
4
7
8
5
6
P5
W
B
N.B.
TACH
R
U
B
MOTOR /
GEARBOX
B W
562
580
577
554
550
552A 553
575C
556
551
576
563
552
COMMON ANALOG P.C. BOARD
4 2
587 608
605 607 W
K
E
Y
558
559
601
606
589
515
POST-FLOW
L3
J60
1 2 3 4 5 6 7 8
601 515A 605 607
606A 608
BURNBACK
606A
B
606
TIMER KIT
(OPTIONAL)
N.A.
556
554
A
B
C
D
E
N.D.
N.B.
W
THERMAL LED
B
COLD FEED
N.C.
558
515A
515
559
GAS PURGE
S1
TRIGGER
INPUT
TRIGGER
CONNECTOR
J4
1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16
1 2 3 4 5 6 1 2 1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16
TRIGGER
INTERLOCK
J1 J2 J3 J14
589
587
S2
N.A.
N.C.
2-STEP
NOTES:
N.A. CAVITY NUMBERING SEQUENCE AS VIEWED FROMCOMPONENT SIDE OF BOARD.
N.B. CAVITY NUMBERING SEQUENCE AS VIEWED FROM LEAD SIDE OF CONNECTOR.
N.C. TOGGLESWITCHES AND POTENTIOMETERS SHOWN FROMCONNECTION SIDE OF SWITCH.
N.D. PIN NEAREST THE FLAT EDGE OF LED LENS ALIGNS WITH WHITE LEAD OF LED SOCKET.
A
L12146-1
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine.
G-3
LF-72/74
G-4
ELECTRICAL DIAGRAMS
WIRING DIAGRAM - ENTIRE MACHINE - CODE 11290, 11291, 11292,11293 (L12146-2) LF-72
CAVITY NUMBERING SEQUENCE
(COMPONENT SIDE OF P.C. BOARD)
1 1 2 1 3
J3 J7
J2
2 3 4 4 6
4
1
8
J5,J8
J9,J60
1
5
8
J1,J14
9 16
GENERAL INFORMATION
ELECTRICAL SYMBOLS PER E1537
COLOR CODE
B -
W -
R -
U -
BLACK
WHITE
RED
BLUE
577
576
575
3
2
1
10K/2W
N.C.
WIRE FEED
SPEED
CONTROL
POTENTIOMETER
FEED
PLATE
INPUT ELECTRODE
CABLE CONNECTION
N.B.
75A
76A
77A
1
2
3
4
P7
75
76
77
77
76
75
3
2
1
10K/2W
N.C.
REMOTE
CONTROL
VOLTAGE
POTENTIOMETER
(OPTIONAL)
552B
552
GAS
SOLENOID
553
B
A
1
2
3
4
P11
1
2
3
4
P4
551A
L2
67
TACH
R
U
B
MOTOR /
GEARBOX
POST-FLOW
J60
BURNBACK
TIMER KIT
(OPTIONAL)
552B
B W
1 2 3 4 5 6 7 8
601 515A 605 607
606A 608
BAFFLE
MOUNTED
RECTIFIER
DIODE
BRIDGE
41
-
580
42
552A
14 PIN
CIRCULAR
CONNECTOR
TO POWER
SOURCE
L1
42VAC
L
M
N
J
K
H
I
F
G
D
E
A
B
C 2
4
77A
76A
75A
41
42
SENSE
J12
67
N.B.
NOTES:
N.A. CAVITY NUMBERING SEQUENCE AS VIEWED FROMCOMPONENT SIDE
OF BOARD.
N.B. CAVITY NUMBERING SEQUENCE AS VIEWED FROM LEAD SIDE OF
CONNECTOR.
N.C. TOGGLESWITCHES AND POTENTIOMETERS SHOWN FROM
CONNECTION SIDE OF SWITCH.
N.D. PIN NEAREST THE FLAT EDGE OF LED LENS ALIGNS WITH WHITE LEAD
OF LEDSOCKET.
N.E. P6 NOT USED.
577
L6
575
575B
575C
J1
N.E.
575C
576
1
2
3
4
P6
562
580
554
550
552A 553 556
A 563
552
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
L4
L5
521
522
551B
521
522
551A
551B
551
563
562
575B
551
550
P10
1
2
3
4
5
6
7
8
R
U
B
1 2 3 4 5 6 1 2
J2 J3
COMMON ANALOG P.C. BOARD
B
W
N.B.
4
2
605
587 608
607
1W
K
E
Y
558
559
601
606
589
515
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
J14
N.A.
L3
606A
1B
606
556
554
N.D.
N.B.
C
D
E
A
B
TRIGGER
INPUT
TRIGGER
CONNECTOR
J13
1W
1B
COLD FEED
N.C.
558
515
515A
559
GAS PURGE
TRIGGER
INTERLOCK
S1
589
587
S2
2-STEP
N.C.
N.A.
THERMAL LED
A
L12146-2
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine.
G-4
LF-72/74
G-5
WIRING DIAGRAM - ENTIRE MACHINE - CODE 11195, 11196, 11197, (L12484) LF-74
ELECTRICAL DIAGRAMS
CAVITY NUMBERING SEQUENCE
(COMPONENT SIDE OF P.C. BOARD)
1 1 2 1 3
J3 J7
J2
2 3 4 4 6
4
1
8
J5,J8
J9,J60
1
5
8
J1,J14
9 16
GENERAL INFORMATION
ELECTRICAL SYMBOLS PER E1537
COLOR CODE
B -
W -
R -
U -
BLACK
WHITE
RED
BLUE
577
576
575
3
2
1
10K/2W
N.C.
WIRE FEED
SPEED
CONTROL
POTENTIOMETER
NORMAL SPEED
B
N.E.
A
1
2
3
4
P11
1
2
3
4
P4
L2
N.B.
75A
76A
77A
1
2
3
4
P7
75
76
77
77
76
75
3
2
1
10K/2W
REMOTE
CONTROL
VOLTAGE
POTENTIOMETER
(OPTIONAL)
N.C.
552B
552
553
GAS
SOLENOID
551A
67
FEED
PLATE
INPUT ELECTRODE
CABLE CONNECTION
TACH
R
U
B
MOTOR /
GEARBOX
POST-FLOW
J60
BURNBACK
TIMER KIT
(OPTIONAL)
552B
B W
BAFFLE
MOUNTED
RECTIFIER
DIODE
BRIDGE
41
-
580
42
HIGH TORQUE
L6
B
N.E.
A
1
2
3
4
P11
1
2
3
4
P6
L4
521
522
551B
551A
551B
551
563
562
575B
551
550
P10
1
2
3
4
5
6
7
8
R
U
B
552A
14 PIN
AMPHENOL
CONNECTOR
TO POWER
SOURCE
L1
42VAC
SENSE
L
M
N
J
K
H
I
F
G
D
E
A
B
C 2
4
77A
76A
75A
41
42
67
J12
NOTES:
N.B.
N.A. CAVITY NUMBERING SEQUENCE AS VIEWED FROMCOMPONENT SIDE
OF BOARD.
N.B. CAVITY NUMBERING SEQUENCE AS VIEWED FROM LEAD SIDE OF
CONNECTOR.
N.C. TOGGLESWITCHES AND POTENTIOMETERS SHOWN FROM
CONNECTION SIDE OF SWITCH.
N.D. PIN NEAREST THE FLAT EDGE OF LED LENS ALIGNS WITH WHITE LEAD
OF LEDSOCKET.
N.E. PLACE P11 IN APPROPRIATE POSITION FORSPEED OR TORQUE.
CONNECTION SHOWN IS FOR NORMAL SPEED. NOTE: NORMAL SPEED
NOT AVAILABLE ON HIGH TORQUE MODEL. HIGH TORQUE NOT AVAILABLE ON
NORMAL SPEED MODEL.
575
575B
575C
577
575C
562
580
554
550
552A 553 556
A
576
563
552
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
J1
L5
521
522
1 2 3 4 5 6 1 2
J2 J3
COMMON ANALOG P.C. BOARD
B
W
N.B.
4
2
587 608
605 607
1W
K
E
Y
558
559
601
606
589
515
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
J14
N.A.
L3
606A
1B
606
1 2 3 4 5 6 7 8
601 515A 605 607
606A 608
556
554
N.D.
N.B.
C
D
E
A
B
TRIGGER
INPUT
TRIGGER
CONNECTOR
J13
1W
1B
COLD FEED
515
558
515A
559
N.C.
GAS PURGE
TRIGGER
INTERLOCK
S1
589
587
S2
2-STEP
N.C.
N.A.
THERMAL LED
A
L12484
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine.
G-5
LF-72/74
G-6
SCHEMATIC - ENTIRE MACHINE - CODE 11075, 11076, 11077 (G4617) LF-72
ELECTRICAL DIAGRAMS
Start-Up
On power-up, the LF-72 will light the motor thermal LED for 0.5 seconds.
If the feeder is powered-up with the trigger depressed, welding will not start until the trigger is released and then depressed again.
Coil measures
21 ohms
Located on case back
GAS
SOLENOID
Off = 0 VDC
OCV = 59 VDC
On = 7.7 VDC
553
552
552B
Plug for future run-in kit.
P9
Located behind front panel
1 2 3 4 5 6 7 8 9 10
50 41A
51
552C
41A
Located on internal panel
552C
552B
552A
41
-
580 42
J6
ARC CURRENT
ARC VOLTAGE
24-42VAC
SENSE
I
K
E
J
L
F
G
N
M
C
D
38VDC at
42VAC input with control board disconnected.
60VDC with control board connected
50
51
41
42
77A
76A
75A
67
2
4
L1
Control Board Summary
•
•
•
•
•
•
Has on-board power supply.
Receives switch signals from Trigger, Cold Feed, Gas Purge, Trigger
Interlock
Reads WFS potentiometer.
Communicates with optional timer kit to control burnback, postflow.
•
Controls motor speed with PWM.
•
Turns Gas Solenoid on, off.
•
Monitors motor current, lights yellow thermal LED if over 4 amps for an extended time period. LED remains lit for 30 – 60 seconds to allow motor to cool.
•
Does NOT support Run-in at this time.
Operates on 24-42 VAC. Maximum WFS and/or maximum pull force may be less when operating at 24 VAC.
Does NOT operate on 115 VAC.
575
575C
575B
562
563
L5
L4
75A
76A
Values for CV300. Others may be different.
0 VDC @ 0 = 5.8 Arc Volts
6.6 VDC @ 10 = 40 ArcVolts
77A
Connector located behind case front
3
4
1
2
P7
75
76
77
Connector located by sheet panel
563
562
575B
551
550
1
5
6
7
8
2
3
4
P5
B
W
1.6V @ 50 IPM
30.6V @ 800 IPM
577
576
575
Gearbox ratio is 2:47
Motor is at electrode potential
Motor is located behind glastic panel
Motor resistance
is 1.5 ohms
MOTOR /
GEARBOX
67
L2
3
2
1
4
5
6
577A
576A
575A
P8
Connector located behind case front
0 VDC MIN. WFS
5 VDC MIN. WFS
POSTFLOW
TIME RANGE
.25 - 10 SEC
POSTFLOW
POT.
FIXED
PULSE
WIDTH
GENERATOR c D
PREFLOW &
POSTFLOW TIMER
LOGIC
A c
5V SIGNAL
GAS FLOW
ENABLE
A b
PREFLOW
TIME FIXED
AT 30msec
COM
BURNBACK
POT
Located on
Timer Board Summary
Case Front
•
Has potentiometers for burnback and postflow.
•
Preflow fixed at 30msec.
•
Burnback range is 0 to 0.25 sec.
•
Postflow range is 0.25 to 10 sec.
•
Receives “Gas Flow Enable” signal.
•
Outputs 100 msec pulses to turn Gas Flow On, Gas
Flow Off.
L3
J60-6
606A
20 OHM = OUTPUT ENABLED
HIGH IMPEDANCE = OUTPUT DISABLED b D
15V SIGNAL
100 msec PULSES
TOGGLE GAS FLOW ON/OFF
COM
+15V
J60-5 J60-8 J60-7 J60-1 J60-3
605
608
607
601
515A
TIMER KIT
(OPTIONAL)
SCHEMATIC =
M20336
B
10K/2W
REMOTE
CONTROL
VOLTAGE
POTENTIOMETER
(OPTIONAL)
10K/2W
WIRE FEED
SPEED
CONTROL
POTENTIOMETER
To Power Source Electrode Connection
580
552
552A
553
577
576
575C
562
563
551
550
556
554
NOT USED NOT USED
4
2
MOLEX
INDEX
KEY
606
605
608
607
601
W
558
515
559
589
587
J1-2
COM
COM
BOARD
POWER
SUPPLY
J1-6 J1-16
+POWER
J1-8 J1-3 J1-13
100K ohm
J1-9 J1-1 J1-15 J1-12 J1-5
+5V +5V
0.1 ohm
J1-11
J1-4
750 ohm
+15V
J2-1 J2-2 J2-3 J2-4 J2-5 J2-6
+ POWER
DRIVE
FET
BRAKE
FET
FILTER
J3-1 J3-2
+15V
J14-1 J14-9 J14-8 J14-14 J14-2 J14-5 J14-4
J14-12 J14-13 J14-7
MOV
20 ohm
J14-10
J14-16 J14-11 J14-15 J14-3
750 ohm
OPEN = 0V
CLOSED = 8V
TRIGGER
MACHINE
OUTPUT
ENABLE
+5V
MOTOR
VOLTAGE
SENSE
BURNBACK
0V = 0.02 SECONDS
5V = 0.25 SECONDS
MOTOR
DRIVE
CIRCUIT
MOTOR
CURRENT
SENSE
SCALING
0-5V PULSE SIGNAL
FREQUENCY = SPEED
0V = MIN SPEED
5V = MAX SPEED
EXTERNAL
GAS
SOLENOID
CONTROL
LOW = CONTROL AT CONTROL BOARD
HIGH = CONTROL AT TIMER BOARD
MICRO
CONTROLLER
PROGRAM
DO NOT USE
NOT FIELD PROGRAMMABLE
TACH
FEEDBACK
(NOT ACTIVE)
WIRE
FEED
SPEED
THERMAL
LED
5V = OFF
4V OR LESS = ON
GAS
PURGE
LOW = DISABLE
HIGH = ENABLE
200 ohm
+15V +15V
200 ohm
SOLENOID
FET
10K ohm
0.25
ohm
GAS
SOLENOID
COLD
FEED
LOW = DISABLE
HIGH = ENABLE
TRIGGER
INTERLOCK
LOW = DISABLE
HIGH = ENABLE
COMMON ANALOG P.C. BOARD
SCHEMATIC = G4559
556
554
C
D
E
A
B
TRIGGER
INPUT
TRIGGER
CONNECTOR
J4
Located on
Case Front
THERMAL LED
5 VDC when lit
B W
Lights when motor current exceeds 4
Amps for an extended time.
15 VDC Open
0 VDC Closed
558
515A
515
COLD FEED
Located on
Case Front
S1
559
GAS PURGE 15 VDC Open
0 VDC Closed
15 VDC in
2 STEP position
589
587
TRIGGER
INTERLOCK
Located on
Case Front
S2
2-STEP
Trigger Interlock does not stop welding when the arc is broken. Pull and release to end the weld.
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
G-6
LF-72/74
G-7
ELECTRICAL DIAGRAMS
SCHEMATIC - ENTIRE MACHINE - CODE 11209, 11210, 11211,11227 (G4617-1) LF-72
Coil measures
21 ohms
Located on case back
GAS
SOLENOID
Off = 0 VDC
OCV = 59 VDC
On = 7.7 VDC
553
552
552B
575
575C
575B
562
563
L4
75A
76A
Values for CV300. Others may be different.
0 VDC @ 0 = 5.8 Arc Volts
6.6 VDC @ 10 = 40 ArcVolts
77A
Connector located behind case front
3
4
1
2
P7
75
76
77
Connector located by sheet panel
563
562
575B
551
550
1
2
3
4
5
6
7
8
P5
B
W
1.6V @ 50 IPM
30.6V @ 800 IPM
577
Gearbox ratio is 2:47
Motor is at electrode potential
Motor is located behind glastic panel
Motor resistance
is 1.5 ohms
MOTOR /
GEARBOX
FEED
PLATE
576
575
67
L2
3
2
1
4
5
6
577A
576A
575A
P8
Connector located behind case front
0 VDC MIN. WFS
5 VDC MAX. WFS
10K/2W
REMOTE
CONTROL
VOLTAGE
POTENTIOMETER
(OPTIONAL)
10K/2W
WIRE FEED
SPEED
CONTROL
POTENTIOMETER
To Power Source Electrode Connection
556
554
A
B
C
D
E
TRIGGER
INPUT
TRIGGER
CONNECTOR
J4
Start-Up
On power-up, the LF-72 will light the motor thermal LED for 0.5 seconds.
If the feeder is powered-up with the trigger depressed, welding will not start until the trigger is released and then depressed again.
J6
ARC CURRENT
ARC VOLTAGE
24-42VAC
SENSE
I
K
G
F
E
J
L
N
M
C
D
38VDC at
42VAC input with control board disconnected.
60VDC with control board connected
41
42
75A
76A
77A
67
2
4
Control Board Summary
•
Has on-board power supply.
•
Receives switch signals from Trigger, Cold Feed, Gas Purge, Trigger
Interlock
•
Reads WFS potentiometer.
•
Communicates with optional timer kit to control burnback, postflow.
•
Controls motor speed with PWM.
•
Turns Gas Solenoid on, off.
•
Monitors motor current, lights yellow thermal LED if over 3.75 amps for an extended time period. LED remains lit for 30 – 60 seconds to allow motor to cool.
•
Does NOT support Run-in at this time.
•
Operates on 24-42 VAC. Maximum WFS and/or maximum pull force may be less when operating at 24 VAC.
•
Does NOT operate on 115 VAC.
Located on internal panel
552B
41
-
580 42
L1
552A
L5
POSTFLOW
TIME RANGE
.25 - 10 SEC
POSTFLOW
POT.
FIXED
PULSE
WIDTH
GENERATOR c D
PREFLOW &
POSTFLOW TIMER
LOGIC
A c
5V SIGNAL
GAS FLOW
ENABLE
A b
PREFLOW
TIME FIXED
AT 30msec
COM
BURNBACK
POT
Timer Board Summary
Located on
Case Front
•
Has potentiometers for burnback and postflow.
•
Preflow fixed at 30msec.
•
Burnback range is 0 to 0.25 sec.
•
Postflow range is 0.25 to 10 sec.
•
Receives “Gas Flow Enable” signal.
•
Outputs 100 msec pulses to turn Gas Flow On, Gas
Flow Off.
L3
J60-6
606A b
605
D
15V SIGNAL
100 msec PULSES
TOGGLE GAS FLOW ON/OFF
COM
+15V
J60-5 J60-8 J60-7 J60-1 J60-3
608
607
601
515A
TIMER KIT
(OPTIONAL)
SCHEMATIC =
M20336
B
20 OHM = OUTPUT ENABLED
HIGH IMPEDANCE = OUTPUT DISABLED
580
552
552A
553
577
576
575C
562
563
551
550
556
554
NOT USED NOT USED
4
2
MOLEX
INDEX
KEY
606
605
608
607
601
W
558
515
559
589
587
J1-2
COM
COM
BOARD
POWER
SUPPLY
+5V
J1-6 J1-16
+POWER
J1-8
J1-3 J1-13
100K ohm
J1-9 J1-1 J1-15 J1-12 J1-5
+5V +5V
+15V
0.1 ohm
J1-11 J1-4
750 ohm
+15V
J2-1 J2-2 J2-3 J2-4 J2-5 J2-6
+ POWER
DRIVE
FET
BRAKE
FET
FILTER
J3-1 J3-2
+15V
J14-1 J14-9 J14-8 J14-14 J14-2 J14-5 J14-4
J14-12 J14-13 J14-7
MOV
20 ohm
J14-10
J14-16 J14-11 J14-15 J14-3
750 ohm
OPEN = 0V
CLOSED = 8V
TRIGGER
MACHINE
OUTPUT
ENABLE
+5V
MOTOR
VOLTAGE
SENSE
BURNBACK
0V = 0.02 SECONDS
5V = 0.25 SECONDS
MOTOR
DRIVE
CIRCUIT
MOTOR
CURRENT
SENSE
SCALING
0-5V PULSE SIGNAL
FREQUENCY = SPEED
0V = MIN SPEED
5V = MAX SPEED
EXTERNAL
GAS
SOLENOID
CONTROL
LOW = CONTROL AT CONTROL BOARD
HIGH = CONTROL AT TIMER BOARD
MICRO
CONTROLLER
PROGRAM
TACH
FEEDBACK
(NOT ACTIVE)
THERMAL
LED
WIRE
FEED
SPEED
COLD
FEED
DO NOT USE
NOT FIELD PROGRAMMABLE
5V = OFF
4V OR LESS = ON
LOW = DISABLE
HIGH = ENABLE
200 ohm
+15V +15V
200 ohm
SOLENOID
FET
10K ohm
0.25
ohm
GAS
SOLENOID
GAS
PURGE
LOW = DISABLE
HIGH = ENABLE
TRIGGER
INTERLOCK
LOW = DISABLE
HIGH = ENABLE
COMMON ANALOG P.C. BOARD
SCHEMATIC = G4559
Located on
Case Front
THERMAL LED
5 VDC when lit
B W
Lights when motor current exceeds 4
Amps for an extended time.
15 VDC Open
0 VDC Closed
558
515A
515
COLD FEED
Located on
Case Front
S1
559
GAS PURGE 15 VDC Open
0 VDC Closed
15 VDC in
2 STEP position
589
587
TRIGGER
INTERLOCK
Located on
Case Front
S2
2-STEP
Trigger Interlock does not stop welding when the arc is broken. Pull and release to end the weld.
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
G-7
LF-72/74
G-8
ELECTRICAL DIAGRAMS
SCHEMATIC - ENTIRE MACHINE - CODE 11290, 11291, 11292,11293 (G4617-2) LF-72
Values for CV305. Others may be different.
0 VDC @ 0 = 5.8 Arc Volts
6.6 VDC @ 10 = 40 ArcVolts
75A
76A
77A
Connector located behind case front
3
4
1
2
P7
75
76
77
Coil measures
21 ohms
Located on case back
GAS
SOLENOID
Off = 0 VDC
OCV = 59 VDC
On = 7.7 VDC
553
552
552B
Located on
Case Back
Located on
Sheet Panel
552B
552A
-
Leads Pass through toroid 2 times.
J12
24-42VAC
SENSE
38VDC at
42VAC input with control board disconnected.
60VDC with control board connected
J
L
I
K
G
F
E
N
M
C
D
41
42
75A
76A
77A
67
2
4
41
L1
580
42
580
J1-2
COM
BOARD
POWER
SUPPLY
552
552A
553
J1-6 J1-16
+POWER
J1-8
COM +5V +15V
10K/2W
REMOTE
CONTROL
VOLTAGE
POTENTIOMETER
(OPTIONAL)
Located on
Case Front
577
576
575
575C
575C
J1-3 J1-13
100K ohm
J1-9
+5V
562
563
575B
562
563
Leads
Pass through toroid 2 times.
L5
+5V
P4
1 2 3 4
P11 1 2 3 4
B
Leads Pass through toroid 2 times.
L6
A
A
550
J1-1 J1-15
J1-12
J1-5
551
556
554
0.1 ohm
Leads Pass through toroid 2 times.
L4
Connector located on sheet panel
551A
J1-11
J1-4
522
521
522
521
P6
551B
1 2 3 4
+ POWER
DRIVE
FET
BRAKE
FET
FILTER
SOLENOID
FET
10K ohm
0.25
ohm
Connector located by sheet panel
563
562
575B
551
550
7
8
5
6
1
2
3
4
P10
R
U
B
B
W
1.6V @ 100 IPM
30.6V @ 800 IPM
Gearbox ratio is 2:47
Motor is at electrode potential
Motor is located behind glastic panel
Motor resistance
is 1.5 ohms
MOTOR /
GEARBOX
67
Leads Pass through toroid 3 times.
L2
20 OHM = OUTPUT ENABLED
HIGH IMPEDANCE = OUTPUT DISABLED
NOT USED
NOT USED
4
2
MOLEX
INDEX
KEY
606
605
608
607
577
576
575
601
0 VDC MIN. WFS
5 VDC MIN. WFS
Located on Case Front
FIXED
PULSE
WIDTH
GENERATOR
Connector located behind sheet panel
b D
15V SIGNAL
100 msec PULSES
TOGGLE GAS FLOW ON/OFF
POSTFLOW
TIME RANGE
.25 - 10 SEC
POSTFLOW
POT.
c D
PREFLOW &
POSTFLOW TIMER
LOGIC
A b
PREFLOW
TIME FIXED
AT 30msec
COM
A c
5V SIGNAL
GAS FLOW
ENABLE
BURNBACK
POT
COM
J60-6 J60-5 J60-8 J60-7 J60-1 J60-3
606A
605
608
607
601
515A
+15V
TIMER KIT
(OPTIONAL)
SCHEMATIC =
M20336
1B
Leads Pass through toroid 2 times.
Motor Connecter Summary
•
P6 not used – required for LF-74 only..
L3
1W
10K/2W
WIRE FEED
SPEED
CONTROL
POTENTIOMETER
Located on
Case Front
To Power Source Electrode Connection
TRIGGER
INPUT
Located on
Case Front
556
A
554
B
C
D
TRIGGER
CONNECTOR
J13
E
Timer Board Summary
•
Has potentiometers for burnback and postflow.
•
Preflow fixed at 30msec.
•
Burnback range is 0 to 0.25 sec.
•
Postflow range is 0.25 to 10 sec.
•
Receives “Gas Flow Enable” signal.
•
Outputs 100 msec pulses to turn Gas Flow On, Gas
Flow Off.
5 VDC when lit
Located on
Case Front
THERMAL LED
1B 1W
Lights when motor current exceeds
3.75 Amps for an extended time.
558
515
559
589
587
15 VDC Open
0 VDC Closed
558
515A
515
COLD FEED
Located on
Case Front
S1
559
GAS PURGE
15 VDC Open
0 VDC Closed
15 VDC in
2 STEP position
589
587
TRIGGER
INTERLOCK
Located on
Case Front
S2
2-STEP
Trigger Interlock does not stop welding when the arc is broken. Pull and release to end the weld.
750 ohm
+15V
J2-1 J2-2 J2-3 J2-4 J2-5 J2-6 J3-1 J3-2
+15V
J14-1 J14-9
J14-8 J14-14 J14-2 J14-5
J14-4 J14-12 J14-13
J14-7
MOV
20 ohm
J14-10 J14-16 J14-11 J14-15 J14-3
750 ohm
OPEN = 0V
CLOSED = 8V
TRIGGER
MOTOR
VOLTAGE
SENSE
MACHINE
OUTPUT
ENABLE
BURNBACK
0V = 0.02 SECONDS
5V = 0.25 SECONDS
+5V
+15V +15V
Start-Up
On power-up, the LF-72 will light the motor thermal LED for 0.5 seconds.
If the feeder is powered-up with the trigger depressed, welding will not start until the trigger is released and then depressed again.
MOTOR
DRIVE
CIRCUIT
Notes
The WFS range of the LF-72 is 50-800 ipm.
EXTERNAL
GAS
SOLENOID
CONTROL
LOW = CONTROL AT CONTROL BOARD
HIGH = CONTROL AT TIMER BOARD
MOTOR
CURRENT
SENSE
SCALING
0-5V PULSE SIGNAL
FREQUENCY = SPEED
0V = MIN SPEED
5V = MAX SPEED
200 ohm
MICRO
CONTROLLER
PROGRAM
DO NOT USE
NOT FIELD PROGRAMMABLE
TACH
FEEDBACK
200 ohm
WIRE
FEED
SPEED
THERMAL
LED
5V = OFF
4V OR LESS = ON
COLD
FEED
LOW = DISABLE
HIGH = ENABLE
GAS
SOLENOID
GAS
PURGE
LOW = DISABLE
HIGH = ENABLE
TRIGGER
INTERLOCK
LOW = DISABLE
HIGH = ENABLE
COMMON ANALOG P.C. BOARD
SCHEMATIC = G4559
Control Board Summary
•
Has on-board power supply.
•
Receives switch signals from Trigger, Cold Feed, Gas Purge, Trigger
Interlock
•
Reads WFS potentiometer.
•
Communicates with optional timer kit to control burnback, postflow.
•
Controls motor speed with PWM.
•
Turns Gas Solenoid on, off.
•
Reads the motor tachometer.
•
Monitors motor current, lights yellow thermal LED if over 3.75 amps for an extended time period. LED remains lit for 30 – 60 seconds to allow motor to cool.
•
Does NOT support Run-in at this time.
•
Operates on 24-42 VAC. Maximum WFS and/or maximum pull force may be less when operating at 24 VAC.
•
Does NOT operate on 115 VAC.
G-8
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
LF-72/74
G-9
SCHEMATIC - ENTIRE MACHINE - CODE 11195, 11196, 11197, (G4942) LF-74
Coil measures
21 ohms
Located on case back
GAS
SOLENOID
Off = 0 VDC
OCV = 59 VDC
On = 7.7 VDC
553
552
552B
Located on
Case Back
Located on
Sheet Panel
552B
552A
-
J12
24-42VAC
SENSE
38VDC at
42VAC input with control board disconnected.
60VDC with control board connected
F
E
K
G
J
I
L
N
M
C
D
Leads Pass through toroid 2 times.
41
L1
41
42
75A
76A
77A
67
2
4
580 42
580
J1-2
COM
BOARD
POWER
SUPPLY
552
552A
553
J1-6 J1-16
+POWER
J1-8
COM +5V +15V
ELECTRICAL DIAGRAMS
Values for CV300. Others may be different.
0 VDC @ 0 = 5.8 Arc Volts
6.6 VDC @ 10 = 40 ArcVolts
75A
76A
77A
Connector located behind case front
1
2
3
4
P7
75
76
77
10K/2W
REMOTE
CONTROL
VOLTAGE
POTENTIOMETER
(OPTIONAL)
Located on
Case Front
284 pulses/sec @ 100 IPM
1139 pulses/sec @ 400 IPM
577
576
575
575C
575C
J1-3 J1-13 J1-9
100K ohm
+5V
575B
562
563
562
563
Leads
Pass through toroid 2 times.
L5
+5V
P4
NORMAL
SPEED
P11
551A
551A
1 2 3 4
1
2 3
4
B
Leads Pass through toroid 2 times.
L6
A
A
550
J1-1
J1-15
J1-12
J1-5
551
556
554
0.1 ohm
Leads Pass through toroid 2 times.
L4
Connector located on sheet panel
521
522
J1-11
J1-4
522
521
P6
551B
1 2 3 4
P11
HIGH
TORQUE
1 2 3 4
B
A
+ POWER
DRIVE
FET
BRAKE
FET
FILTER
SOLENOID
FET
10K ohm
0.25
ohm
Connector located by sheet panel
563
562
575B
551
550
7
8
5
6
1
2
3
4
P10
R
U
B
5 VDC
B
W
1.6V @ 100 IPM
30.6V @ 800 IPM
Gearbox ratio is 2:47
Motor is at electrode potential
Motor is located behind glastic panel
Motor resistance
is 1.5 ohms
MOTOR /
GEARBOX
67
Leads Pass through toroid 3 times.
L2
Located on Case Front
FIXED
PULSE
WIDTH
GENERATOR b D
15V SIGNAL
100 msec PULSES
TOGGLE GAS FLOW ON/OFF
POSTFLOW
TIME RANGE
.25 - 10 SEC
POSTFLOW
POT.
c D
PREFLOW &
POSTFLOW TIMER
LOGIC
A b
PREFLOW
TIME FIXED
AT 30msec
COM
A c
5V SIGNAL
GAS FLOW
ENABLE
BURNBACK
POT
COM
+15V
J60-6 J60-5 J60-8 J60-7 J60-1 J60-3
TIMER KIT
(OPTIONAL)
SCHEMATIC =
M20336
606A
605
608
607
601
515A
1B
Motor Connecter Summary
•
High Torque Setting engages
Machine Select by connecting Pins 1 and 2 on Connector J2.
•
High Torque not available on Normal
Speed Model.
•
Normal Speed Setting not available on High Torque Model.
Leads Pass through toroid 2 times.
L3
20 OHM = OUTPUT ENABLED
HIGH IMPEDANCE = OUTPUT DISABLED
NOT USED
NOT USED
4
2
MOLEX
INDEX
KEY
606
605
608
607
577
576
575
601
0 VDC MIN. WFS
5 VDC MIN. WFS
1W
10K/2W
WIRE FEED
SPEED
CONTROL
POTENTIOMETER
Located on
Case Front
To Power Source Electrode Connection
558
515
559
589
TRIGGER
INPUT
Located on
Case Front
556
A
554
B
C
D
TRIGGER
CONNECTOR
J13
E
Timer Board Summary
•
Has potentiometers for burnback and postflow.
•
Preflow fixed at 30msec.
•
Burnback range is 0 to 0.25 sec.
•
Postflow range is 0.25 to 10 sec.
•
Receives “Gas Flow Enable” signal.
•
Outputs 100 msec pulses to turn Gas Flow On, Gas
Flow Off.
5 VDC when lit
1B
Located on
Case Front
THERMAL LED
1W
Lights when motor current exceeds
3.75 Amps for an extended time.
587
15 VDC Open
0 VDC Closed
558
515A
515
COLD FEED
Located on
Case Front
S1
559
GAS PURGE
15 VDC Open
0 VDC Closed
15 VDC in
2 STEP position
589
587
TRIGGER
INTERLOCK
Located on
Case Front
S2
2-STEP
Trigger Interlock does not stop welding when the arc is broken. Pull and release trigger to end the weld.
750 ohm
+15V
J2-1 J2-2 J2-3 J2-4 J2-5 J2-6 J3-1 J3-2
+15V
J14-1 J14-9
J14-8 J14-14 J14-2 J14-5
J14-4 J14-12 J14-13
J14-7
MOV
20 ohm
J14-10 J14-16 J14-11 J14-15 J14-3
750 ohm
OPEN = 0V
CLOSED = 8V
TRIGGER
MOTOR
VOLTAGE
SENSE
MACHINE
OUTPUT
ENABLE
BURNBACK
0V = 0.02 SECONDS
5V = 0.25 SECONDS
+5V
+15V +15V
Start-Up
On power-up, the LF-74 will light the motor thermal LED for 0.5 seconds.
If the feeder is powered-up with the trigger depressed, welding will not start until the trigger is released and then depressed again.
MOTOR
DRIVE
CIRCUIT
Notes
The WFS range of this code of LF-74 is
100-800 ipm. The WFS range of the
LF-72 is 50-800 ipm.
MOTOR
CURRENT
SENSE
SCALING
EXTERNAL
GAS
SOLENOID
CONTROL
LOW = CONTROL AT CONTROL BOARD
HIGH = CONTROL AT TIMER BOARD
0-5V PULSE SIGNAL
FREQUENCY = SPEED
0V = MIN SPEED
5V = MAX SPEED
200 ohm
MICRO
CONTROLLER
PROGRAM
DO NOT USE
NOT FIELD PROGRAMMABLE
TACH
FEEDBACK
200 ohm
WIRE
FEED
SPEED
THERMAL
LED
5V = OFF
4V OR LESS = ON
COLD
FEED
LOW = DISABLE
HIGH = ENABLE
GAS
SOLENOID
GAS
PURGE
LOW = DISABLE
HIGH = ENABLE
TRIGGER
INTERLOCK
LOW = DISABLE
HIGH = ENABLE
COMMON ANALOG P.C. BOARD
SCHEMATIC = G4559
Control Board Summary
•
Has on-board power supply.
•
Receives switch signals from Trigger, Cold Feed, Gas Purge, Trigger
Interlock
•
Reads WFS potentiometer.
•
Communicates with optional timer kit to control burnback, postflow.
•
Controls motor speed with PWM.
•
Turns Gas Solenoid on, off.
•
Reads the motor tachometer.
•
Monitors motor current, lights yellow thermal LED if over 3.75 amps for an extended time period. LED remains lit for 30 – 60 seconds to allow motor to cool.
•
Does NOT support Run-in at this time.
•
Operates on 24-42 VAC. Maximum WFS and/or maximum pull force may be less when operating at 24 VAC.
•
Does NOT operate on 115 VAC.
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
G-9
LF-72/74
G-10
SCHEMATIC - COMMON ANALOG CONTROL PC BOARD - (G4559 SHEET 1)
ELECTRICAL DIAGRAMS
G-10
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
LF-72/74
G-11
SCHEMATIC - COMMON ANALOG CONTROL PC BOARD - (G4559 SHEET 2)
ELECTRICAL DIAGRAMS
G-11
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
LF-72/74
G-12
SCHEMATIC - COMMON ANALOG CONTROL PC BOARD - (G4559 SHEET 3)
ELECTRICAL DIAGRAMS
G-12
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.
LF-72/74
G-13
PC BOARD ASSEMBLY - COMMON ANALOG CONTROL - (G4560-2E0)
ELECTRICAL DIAGRAMS
G-13
NOTE:
Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not available from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.
LF-72/74
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Key features
- Advanced inverter technology for superior arc performance
- Digital display for precise control of welding parameters
- Multiple welding modes for versatility
- Compact and lightweight design for portability
- Built-in safety features for peace of mind
- Compatible with a wide range of welding electrodes