TROUBLE SHOOTING CHART. Snap-On MIG220

TROUBLE SHOOTING

(SYMBOL*)

FOR TECH. SERVICE, CALL TOLL-FREE 1-800-232-9353

The Trouble Shooting Chart is a guide in identifying and correcting possible troubles which may occur when operating this equipment.

FAULT POSSIBLE CAUSE

EQUIPMENT MALFUNCTION

REMEDY

No main power, MIG220 switch is "OFF".

(CB1)

Turn switch "on".

fan does not Wall breaker is "tripped".

Reset wall breaker.

operate, "Open" circuit breaker Reset or replace

"on" indicator on MIG220.

(CB1) breaker.

light is off.

Loose or broken connection Tighten or repair in power input circuit.

connection.

Main power on, MIG torch unplugged.

torch Faulty trigger switch.

(S1)

Plug in MIG torch.

Replace micro switch.

trigger activated,

Fault in torch cable.

Check torch cable for continuity.

no response.

Loose or broken connection Check or repair on wiring harness.

connections.

Wire feed motor unplugged.

Plug in motor.

(RC3)

Faulty control transformer.

Check for 28VAC output.

(T2)

Main power on, Pressure roll arm unlatched. Latch arm & add tension.

torch "Slippage" at drive rolls.

Increase drive roll trigger activated, Wire path restricted.

tension. See page 7.

Clean path or replace no wire feed but contactor 5 amp mini breaker is operates & gas flows.

tripped.

(CB2)

Wire feed circuit board needs calibrated.

torch liner.

Reset or replace breaker.

Calibrate wire feed circuit board. See page 17.

Replace circuit board.

Defective wire feed circuit board.

(PC1)

Faulty wire feed motor or connection.

(M)

Repair or replace faulty item.

Check motor on a

12VDC battery.

Faulty motor relay.

(CR1)

Sand points or replace relay.

Loose or broken connection.

Tighten or repair connection.

(continued on following page)

(SYMBOL*)

- USE THIS IDENTIFIER, ALONG WITH THE SCHEMATIC DIAGRAM FOUND IN THE SERVICE

MANUAL, FOR TROUBLE-SHOOTING PURPOSES.

Snap-on Tools Corporation Kenosha, WI 53141-1410 13

TROUBLE SHOOTING (Cont.)

(SYMBOL*)

FOR TECH. SERVICE, CALL 1-800-232-9353

FAULT POSSIBLE CAUSE

EQUIPMENT MALFUNCTION (Cont.)

REMEDY

Main power on, Loose torch thumb screw.

torch Broken or loose connection.

Tighten thumb screw.

Check cables for trigger activated, continuity.

Repair or tighten no welding current, but Unplugged or faulty power gas flows & wire feeds.

contactor switch.

(W) connections.

Plug in or replace switch.

208/230V selector wire off.

Reattach wire.

(W)

"Opened" thermal switch.

(TP1)

Faulty diodes.

(D1-D4)

Allow unit to cool, then retry.

Check diodes. See page

16.

Torch trigger activated, no gas flow,

No shielding gas

- tank empty.

Loose or broken connections.

but contactor Faulty Gas solenoid operates & valve.

(GS) wire feeds.

Clogged gas flow path.

Replace tank.

Tighten or repair connections.

Repair or replace valve.

Locate & clean clog.

"Jerky" or

"slipping" wire feed.

sion.

FAULTY WELDS

Worn , kinked or dirty torch Clean or replace liner.

liner.

Wire spool turns too hard.

Lubricate spool shaft.

Worn double v-groove drive Replace drive roll.

roll.

Weak pressure roll spring.

Replace spring.

Worn or dirty contact tip.

Replace contact tip.

Worn inlet guide(s).

Sticking pressure roll.

Clean or replace guides.

Replace pressure roll.

Feed roll tension incorrect. Adjust feed roll ten-

See page 7.

14 Snap-on Tools Corporation Kenosha, WI 53141-1410

TROUBLE SHOOTING (Cont.)

(SYMBOL*)

FOR TECH. SERVICE, CALL TOLL-FREE 1-800-232-9353

FAULT

"Birdnesting"

(Wire wrapping around drive rolls)

"Cold" weld puddle.

POSSIBLE CAUSE

FAULTY WELDS (Cont.)

REMEDY

Excessive feed roll tension. Reduce tension. See page

7.

Poor alignment.

Make sure wire is properly aligned

Oversize contact tip.

across roller.

Replace contact tip with correct size.

Incorrect machine settings.

Increase heat & wire speed.

Incorrect shielding gas.

Excessive wire stick-out.

Replace with proper gas.

Hold torch closer to

Poor connections.

Faulty diode.

(D1-D4) work.

Check and tighten all connections.

Test diodes, replace faulty diode(s). See page 16.

Heavy spatter.

Incorrect machine settings.

Increase heat, decrease wire feed speed.

Incorrect shielding gas.

Excessive wire stick-out.

Replace with proper gas.

Hold torch closer to work.

Porous welds.

No shielding gas.

Not enough gas flow.

Contaminated wire.

Faulty gas solenoid.

Turn on gas.

Check hoses for leaks, make sure cylinder is not empty. Increase flow rate.

Change wire.

Replace solenoid.

(GS)

Incorrect electrode wire.

Use correct wire.

Contaminated base material.

Clean or etch base material.

(SYMBOL*)

- USE THIS IDENTIFIER, ALONG WITH THE SCHEMATIC DIAGRAM FOUND IN THE SERVICE

MANUAL, FOR TROUBLE-SHOOTING PURPOSES.

Snap-on Tools Corporation Kenosha, WI 53141-1410 15

TESTING AND REPLACING DIODES

Silicon diodes have proven to be highly reliable. However, weld spatter build-up in the torch can short out and cause diode overload and consequent failure. The following information is provided as a guide should a failure be suspected.

Silicon diodes exhibit two main fault conditions:

1. "Open Circuit" - causes a reduction in welder output.

2. "Short Circuit" - causes the circuit breaker to trip.

If a fault is suspected, the diode may be tested as follows:

1. Remove the top connection of each diode to be tested.

2. Using a Volt-Ohm Meter set on diode or 2K, check for continuity through the diode in both directions. If there is no continuity in either direction, the diode is in

"open circuit" condition and must be replaced. If there is continuity in both directions, the diode is in "short circuit" condition and must be replaced.

If there is continuity in one direction only, the diode is functioning properly.

3. If all the diodes check out satisfactorily with the Volt-

Ohm Meter, a load check must be made using a twelve volt battery and a twelve volt headlight bulb.

CAUTION

NEVER use a "megger" or a high voltage device to test a diode.

4. Connect the headlight bulb to one end of the diode. Test for electrical flow in both directions as follows. First, test by connecting a lead from the battery positive

(+) terminal to the light bulb and a lead from the battery negative (-) terminal to the other end of the diode. Test again by reversing the connections. (See Figure 16.) The headlight bulb should light with the current flow in one

(1) direction only - not both.

12 VOLT

HEADLIGHT

BULB

DIODE

+ -

12 VOLT

BATTERY

12 VOLT

HEADLIGHT

BULB

DIODE

+ -

12 VOLT

BATTERY

FIGURE 16.

DIODE LOAD CHECK CONNECTION DIAGRAM

- TEST FOR FLOW IN BOTH DIRECTIONS

5. When replacing diodes, it is very important that a heat conductive compound (Radio Shack

#276-1372) be used where the diode makes contact with the aluminum heat sink. Do not grease the threads on the diode.

16 Snap-on Tools Corporation Kenosha, WI 53141-1410

WIRE FEED CALIBRATION

Due to INPUT LINE VOLTAGE variations supplied to the welding machine. The WIRE FEED SPEED should be checked for proper operation.

TO CHECK

1. Remove any tension on the drive roll.

2. Turn the wire speed dial (on the front of the machine) to "0".

3. Activate the torch trigger.

4. The bottom drive roll should rotate very slowly(non-jerky).

5. If this proves to be true, no adjustment is required.

RESISTOR

IF ADJUSTMENT IS REQUIRED

1. Remove the top cover assembly from the unit.

2. Locate the printed circuit board.

3. Referring to Figure 17, locate the trim resistor, this is located in the upper right hand corner of the wire feed PC board.

4. Turn the wire speed dial (on the front of the machine) to "0".

5. Remove any tension on the drive roll.

6. Activate the torch trigger.

FIGURE 17. WIRE FEED PC BOARD

7. Rotate the trim resistor, back and forth, until the bottom drive roll moves.

8. Calibrate so the bottom drive roll rotates very slowly (nonjerky).

9. If calibrated correctly the wire speed dial (on the front of the machine) should affect the speed of the drive roll from "0" thru

"10".

10.Adjustment is now complete!

Snap-on Tools Corporation Kenosha, WI 53141-1410 17