Model 2000-SCAN Scanner Card Instruction Manual

Model 2000-SCAN Scanner Card Instruction Manual
Model 2000-SCAN
Scanner Card
Instruction Manual
Contains Operating and Servicing Information
WARRANTY
Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of
1 year from date of shipment.
Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables,
rechargeable batteries, diskettes, and documentation.
During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.
To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in
Cleveland, Ohio. You will be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service facility. Repairs will be made and the product returned, transportation prepaid.
Repaired or replaced products are warranted for the balance of the original warranty period, or at least 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from product modification without Keithley’s express written
consent, or misuse of any product or part. This warranty also does not apply to fuses, software, non-rechargeable
batteries, damage from battery leakage, or problems arising from normal wear or failure to follow instructions.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING
ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE
REMEDIES PROVIDED HEREIN ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.
NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR
ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF
THE USE OF ITS INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS
BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL AND INSTALLATION,
LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR DAMAGE TO PROPERTY.
Keithley Instruments, Inc. • 28775 Aurora Road • Cleveland, OH 44139 • 440-248-0400 • Fax: 440-248-6168 • http://www.keithley.com
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1/99
Model 2000-SCAN Scanner Card
Instruction Manual
©1994, Keithley Instruments, Inc.
All rights reserved.
Cleveland, Ohio, U.S.A.
Fourth Printing, April 1999
Document Number: 2000-SCAN-901-01 Rev. D
Manual Print History
The print history shown below lists the printing dates of all Revisions and Addenda created
for this manual. The Revision Level letter increases alphabetically as the manual undergoes subsequent updates. Addenda, which are released between Revisions, contain important change information that the user should incorporate immediately into the manual. Addenda are numbered
sequentially. When a new Revision is created, all Addenda associated with the previous Revision
of the manual are incorporated into the new Revision of the manual. Each new Revision includes
a revised copy of this print history page.
Revision A (Document Number 2000-SCAN-901-01) ............................................November 1994
Revision B (Document Number 2000-SCAN-901-01) .............................................. February 1995
Addendum B (Document Number 2000-SCA-901-02) ................................................... April 1995
Addendum B (Document Number 2000-SCA-901-03) ........................................... December 1995
Revision C (Document Number 2000-SCAN-901-01) ..................................................... May 1998
Revision D (Document Number 2000-SCAN-901-01) .................................................... April 1999
All Keithley product names are trademarks or registered trademarks of Keithley Instruments, Inc.
Other brand names are trademarks or registered trademarks of their respective holders.
Safety Precautions
The following safety precautions should be observed before using this product and any associated instrumentation. Although some instruments and accessories would normally be used with non-hazardous voltages, there
are situations where hazardous conditions may be present.
This product is intended for use by qualified personnel who recognize shock hazards and are familiar with the
safety precautions required to avoid possible injury. Read the operating information carefully before using the
product.
The types of product users are:
Responsible body is the individual or group responsible for the use and maintenance of equipment, for ensuring
that the equipment is operated within its specifications and operating limits, and for ensuring that operators are
adequately trained.
Operators use the product for its intended function. They must be trained in electrical safety procedures and
proper use of the instrument. They must be protected from electric shock and contact with hazardous live circuits.
Maintenance personnel perform routine procedures on the product to keep it operating, for example, setting
the line voltage or replacing consumable materials. Maintenance procedures are described in the manual. The
procedures explicitly state if the operator may perform them. Otherwise, they should be performed only by service personnel.
Service personnel are trained to work on live circuits, and perform safe installations and repairs of products.
Only properly trained service personnel may perform installation and service procedures.
Exercise extreme caution when a shock hazard is present. Lethal voltage may be present on cable connector
jacks or test fixtures. The American National Standards Institute (ANSI) states that a shock hazard exists when
voltage levels greater than 30V RMS, 42.4V peak, or 60VDC are present. A good safety practice is to expect
that hazardous voltage is present in any unknown circuit before measuring.
Users of this product must be protected from electric shock at all times. The responsible body must ensure that
users are prevented access and/or insulated from every connection point. In some cases, connections must be
exposed to potential human contact. Product users in these circumstances must be trained to protect themselves
from the risk of electric shock. If the circuit is capable of operating at or above 1000 volts, no conductive part
of the circuit may be exposed.
As described in the International Electrotechnical Commission (IEC) Standard IEC 664, digital multimeter
measuring circuits (e.g., Keithley Models 175A, 199, 2000, 2001, 2002, and 2010) are Installation Category II.
All other instruments’ signal terminals are Installation Category I and must not be connected to mains.
Do not connect switching cards directly to unlimited power circuits. They are intended to be used with impedance limited sources. NEVER connect switching cards directly to AC mains. When connecting sources to
switching cards, install protective devices to limit fault current and voltage to the card.
Before operating an instrument, make sure the line cord is connected to a properly grounded power receptacle.
Inspect the connecting cables, test leads, and jumpers for possible wear, cracks, or breaks before each use.
For maximum safety, do not touch the product, test cables, or any other instruments while power is applied to
the circuit under test. ALWAYS remove power from the entire test system and discharge any capacitors before:
connecting or disconnecting cables or jumpers, installing or removing switching cards, or making internal
changes, such as installing or removing jumpers.
Do not touch any object that could provide a current path to the common side of the circuit under test or power
line (earth) ground. Always make measurements with dry hands while standing on a dry, insulated surface capable of withstanding the voltage being measured.
The instrument and accessories must be used in accordance with its specifications and operating instructions or
the safety of the equipment may be impaired.
Do not exceed the maximum signal levels of the instruments and accessories, as defined in the specifications
and operating information, and as shown on the instrument or test fixture panels, or switching card.
When fuses are used in a product, replace with same type and rating for continued protection against fire hazard.
Chassis connections must only be used as shield connections for measuring circuits, NOT as safety earth ground
connections.
If you are using a test fixture, keep the lid closed while power is applied to the device under test. Safe operation
requires the use of a lid interlock.
If a
tation.
screw is present, connect it to safety earth ground using the wire recommended in the user documen-
The ! symbol on an instrument indicates that the user should refer to the operating instructions located in
the manual.
The
symbol on an instrument shows that it can source or measure 1000 volts or more, including the combined effect of normal and common mode voltages. Use standard safety precautions to avoid personal contact
with these voltages.
The WARNING heading in a manual explains dangers that might result in personal injury or death. Always
read the associated information very carefully before performing the indicated procedure.
The CAUTION heading in a manual explains hazards that could damage the instrument. Such damage may
invalidate the warranty.
Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and all test cables.
To maintain protection from electric shock and fire, replacement components in mains circuits, including the
power transformer, test leads, and input jacks, must be purchased from Keithley Instruments. Standard fuses,
with applicable national safety approvals, may be used if the rating and type are the same. Other components
that are not safety related may be purchased from other suppliers as long as they are equivalent to the original
component. (Note that selected parts should be purchased only through Keithley Instruments to maintain accuracy and functionality of the product.) If you are unsure about the applicability of a replacement component,
call a Keithley Instruments office for information.
To clean an instrument, use a damp cloth or mild, water based cleaner. Clean the exterior of the instrument only.
Do not apply cleaner directly to the instrument or allow liquids to enter or spill on the instrument. Products that
consist of a circuit board with no case or chassis (e.g., data acquisition board for installation into a computer)
should never require cleaning if handled according to instructions. If the board becomes contaminated and operation is affected, the board should be returned to the factory for proper cleaning/servicing.
Rev. 2/99
Table of Contents
1 General Information
Introduction..........................................................................................1-2
Features................................................................................................1-2
Warranty information...........................................................................1-2
Manual addenda...................................................................................1-3
Safety symbols and terms ....................................................................1-3
Specifications.......................................................................................1-3
Unpacking and inspection....................................................................1-4
Repacking for shipment.......................................................................1-4
2 Card Connections and Installation
Introduction..........................................................................................2-2
Handling precautions ...........................................................................2-3
Connections .........................................................................................2-4
Typical connecting schemes ................................................................2-9
Card installation and removal ............................................................2-15
3 Operation
Introduction..........................................................................................3-2
Signal limitations .................................................................................3-3
Scanner card detection.........................................................................3-4
Model 2000 Multimeter front panel scanner controls and SCPI
scanner commands ..........................................................................3-5
SCPI scanner commands .....................................................................3-8
Model 2001/2002 front panel scanner controls and SCPI scanner
commands......................................................................................3-10
RTD temperature measurements........................................................3-16
Typical applications ...........................................................................3-18
Measurement considerations .............................................................3-22
4 Service Information
Introduction..........................................................................................4-2
Handling and cleaning precautions......................................................4-3
Performance verification......................................................................4-4
Special handling of static-sensitive device ........................................4-12
Principles of operation.......................................................................4-13
Troubleshooting .................................................................................4-14
5 Replaceable Parts
Introduction ......................................................................................... 5-2
Parts list ............................................................................................... 5-2
Ordering information........................................................................... 5-2
Factory service .................................................................................... 5-3
Component layout and schematic diagram ......................................... 5-3
A Specifications
List of Illustrations
2 Card Connections and Installation
Model 2000-SCAN simplified schematic ........................................... 2-4
Card connectors................................................................................... 2-5
Output connections.............................................................................. 2-7
Routing wires through cable clamp..................................................... 2-8
Connections for voltage scanning ....................................................... 2-9
Typical connections for 2-wire resistance scanning.......................... 2-10
Typical connections for 4-wire resistance scanning.......................... 2-11
Current shunt locations...................................................................... 2-12
Current connections........................................................................... 2-14
Card installation ................................................................................ 2-16
2-pole output connections ................................................................. 2-17
4-pole output connections ................................................................. 2-18
3 Operation
2-wire resistance test connections ..................................................... 3-18
4-wire resistance test connections ..................................................... 3-19
Combining 2-pole and 4-pole switching (Model 2001/2002) ........... 3-20
Connections for current measurements ............................................. 3-21
Path isolation resistance .................................................................... 3-22
Voltage attenuation by path isolation resistance................................ 3-23
Power line ground loops.................................................................... 3-24
Eliminating ground loops .................................................................. 3-25
4 Service Information
Connections for path resistance checks............................................... 4-7
Connections for contact potential tests................................................ 4-8
Connections for same-channel isolation tests ..................................... 4-9
Connections for channel-to-channel isolation tests........................... 4-10
Connections for HI ad LO terminal to chassis ground
isolation tests....................................................................... 4-11
Block diagram ................................................................................... 4-13
List of Tables
3 Operation
Summary of SCPI scanner commands ................................................3-9
4 Service Information
Recommended verification equipment ................................................4-5
Recommended troubleshooting equipment .......................................4-14
Troubleshooting procedure ................................................................4-15
1
General
Information
1-2
General Information
Introduction
This section contains general information about the Model 2000-SCAN scanner card. The
Model 2000-SCAN provides 10 channels of 2-pole relay switching. The channels can be configured for 4-pole operation.
Section 1 is arranged in the following manner:
Features
Warranty information
Manual addenda
Safety symbols and terms
Specifications
Unpacking and inspection
Repacking for shipment
Features
The Model 2000-SCAN is a scanner card designed to be installed in the Model 2000 Multimeter, Model 2001 Multimeter, and Model 2002 Multimeter.
Key features include:
•
•
•
Ten channels of 2-pole relay input.
Channels configurable for 4-pole operation.
Multiplex one of ten 2-pole, or one of five 4-pole channels into a Model 2000/2001/2002
Multimeter.
Warranty information
Warranty information is located at thew front of this instruction manual. Should your Model
2000-SCAN require warranty service, contact the Keithley representative or authorized repair
facility in your area for further information. When returning the scanner card for repair, be sure
to fill out and include the service form at the back of this manual in order to provide the repair
facility with the necessary information.
General Information
1-3
Manual addenda
Any improvements or changes concerning the scanner card or manual will be explained in an
addendum included with the card. Addenda are provided in a page replacement format. Simply
replace the obsolete pages with the new pages.
Safety symbols and terms
The following symbols and terms may be found on an instrument or used in this manual.
The ! symbol on an instrument indicates that the user should refer to the operating
instructions located in the instruction manual.
The
symbol on an instrument shows that high voltage may be present on the terminal(s).
Use standard safety precautions to avoid personal contact with these voltages.
The WARNING heading used in this manual explains dangers that might result in personal
injury or death. Always read the associated information very carefully before performing the
indicated procedure.
The CAUTION heading used in this manual explains hazards that could damage the scanner
card. Such damage may invalidate the warranty.
Specifications
Model 2000-SCAN specifications are found in Appendix A. These specifications are exclusive of the multimeter specifications.
1-4
General Information
Unpacking and inspection
Inspection for damage
The Model 2000-SCAN is packaged in a re-sealable, anti-static bag to protect it from damage
due to static discharge and from contamination that could degrade its performance. Before
removing the card from the bag, observe the precautions below on handling.
Handling precautions
•
•
Always grasp the card by the side edges and covers. Do not touch the board surfaces or
components.
When the card is not installed in a multimeter, keep the card in the anti-static bag, and
store it in the original packing carton. After removing the card from its anti-static bag,
inspect it for any obvious signs of physical damage. Report any such damage to the shipping agent immediately.
Shipment contents
The following items are included with every Model 2000-SCAN order:
•
•
•
•
Model 2000-SCAN Scanner Card
Model 2000-SCAN Instruction Manual
CA-109 test lead set for output connections (two red, two black)
Additional accessories as ordered
Instruction manual
If an additional Model 2000-SCAN Instruction Manual is required, order the manual package, Keithley part number 2000-SCAN-901-00. The manual package includes an instruction
manual and any pertinent addenda.
Repacking for shipment
Should it become necessary to return the Model 2000-SCAN for repair, carefully pack the
unit in its original packing carton or the equivalent, and include the following information:
•
•
•
Advise as to the warranty status of the scanner card.
Write ATTENTION REPAIR DEPARTMENT on the shipping label.
Fill out and include the service form located at the back of this manual.
2
Card Connections
and Installation
2-2
Card Connections and Installation
Introduction
WARNING
The procedures in this section are intended only for qualified service personnel. Do not perform these procedures unless you are qualified to do so. Failure to recognize and observe normal safety precautions could result in
personal injury or death.
This section includes information on making connections to the Model 2000-SCAN and on
installing the card in a Model 2000/2001/2002 Multimeter. This section is ar-ranged as follows:
Handling precautions — Explains precautions that must be followed to prevent contamination to the scanner card assembly. Contamination could degrade the performance of the scanner
card.
Connections — Covers the basics for connecting external circuitry to the scanner card.
Typical connection schemes — Provides some typical connection schemes for 2-pole and
4-pole operation.
Card installation and removal — Summarizes the procedure to install the scanner card in a
multimeter, outlines scanner card output connections, and describes how to remove the card.
Card Connections and Installation
2-3
Handling precautions
To maintain high impedance isolation between channels, care should be taken when handling
the scanner card to avoid contamination from such foreign materials as body oils. Such contamination can substantially lower leakage resistances, degrading card performance. To avoid possible contamination, always grasp the scanner card by the side edges or covers. Do not touch
board surfaces, components, or areas adjacent to electrical contacts.
Dirt build-up over a period of time is another possible source of contamination. To avoid this
problem, operate the multimeter and scanner card in a clean environment. If the card becomes
contaminated, it should be thoroughly cleaned as explained in Section 4 “Handling and cleaning
precautions”.
2-4
Card Connections and Installation
Connections
This paragraph provides the information necessary to connect your external test circuitry to
the scanner card.
WARNING
NOTE
The following connection information is intended to be used by qualified service personnel. Failure to recognize and observe standard safety precautions
could result in personal injury or death.
All connecting wires or leads must be connected to the card before it is installed in a
multimeter.
Card configuration
Figure 2-1 shows a simplified schematic diagram of the Model 2000-SCAN. The scanner
card has ten input channels and two outputs. Channels 1-10 are all switched by relays.
4-pole paired channels are as follows:
•
•
•
•
•
Figure 2-1
Model 2000SCAN simplified
schematic
Channels 1 and 6
Channels 2 and 7
Channels 3 and 8
Channels 4 and 9
Channels 5 and 10
User-installed
current shunt
Channel 1
HI
LO
Channel 2-4
Channel 5
HI
HI
LO
LO
HI
LO
User-installed
current shunt
Channel 6
HI
LO
Channel 7-9
Channel 10
HI
LO
4-Pole
2-Pole
OUT A
(To DMM input jacks)
OUT B
(To DMM sense jacks)
Card Connections and Installation
2-5
Card connectors
Figure 2-2 shows the input/output connectors for the card. Card connections include:
•
•
•
CH 1-10 (channels 1-10): HI and LO input terminals are provided for each of the 10
channels on the card.
OUT A: HI and LO output connections for all ten channels in the 2-pole mode or channels 1-5 in the 4-pole mode.
OUT B: HI and LO output connections for channels 6-10 in the 4-pole mode.
In order to gain access to the connections, first open the plastic shield by pressing in on the
locking tab. Swing the shield away from the circuit board.
Figure 2-2
Card connectors
Channels 1-5, OUT A
H
L
H
L
H
L
H
L
H
L
H
Channels 6-10, OUT B
L
CH 1 CH 2 CH 3 CH 4 CH 5 OUT A
Locking Tab
H
L
H
L
H
L
H
L
H L
H
L
CH 6 CH 7 CH 8 CH 9 CH 10 OUT B
Plastic Shield
2-6
Card Connections and Installation
Wiring procedure
Perform the following procedure to wire circuitry to the screw terminals on the scanner card.
WARNING
Make sure all power is off and any stored energy in external circuitry is discharged before connecting or disconnecting wires.
CAUTION
Mechanical shock may open or close latching relays on the scanner card.
Before enabling any external sources, open all relays by inserting the Model
2000-SCAN into the multimeter and turning on the power.
1.
2.
NOTE
3.
4.
5.
6.
Open the plastic shield to gain access to the connectors.
Strip approximately 5/16” of insulation from the end of each wire, then twist the strands
together.
#22 AWG stranded wire is recommended for scanner card connections.
Loosen the screw terminal, then insert the wire into the access hole.
While holding the wire in place, tighten the connector screw securely.
Repeat steps 1 through 3 for each wire to be connected.
Dress input wires through the cable clamp, as discussed in Section 2 “Dressing leads”.
Card Connections and Installation
2-7
Output connections
Use the supplied test leads for scanner output connections. Connect red leads to the output
(OUT A and OUT B) HI terminals, and connect black leads to the output LO terminals. See Figure 2-3 for details. Dress output test leads through the cable clamp, as described in Section 2
“Dressing leads”. After all wires are connected and secure, close the plastic shield, and secure it
with the locking tab.
NOTE
If you intend to use the scanner card only in the 2-pole mode, it is not necessary to
connect output leads to both OUT A and OUT B. Use only OUT A for the 2-pole mode.
After the scanner card is installed, the output leads must be connected to the multimeter rear
panel input jacks. See Section 2 “Output connections to multimeter” for details.
Figure 2-3
Output connections
HI
HI
To DMM
Input
LO
LO
Red
To DMM
Sense
Black
Black
Red
H
L
H
L
H
L
H
L
H
L
H
L
CH 1 CH 2 CH 3 CH 4 CH 5 OUT A
H
L
H
L
H
L
H
L
H L
H
L
CH 6 CH 7 CH 8 CH 9 CH 10 OUT B
Note: OUT B connections not required
for 2-pole operation. Plastic shield
not shown.
2-8
Card Connections and Installation
Dressing leads
After wires are connected to the terminal blocks, they should be dressed through the cable
clamp as shown in Figure 2-4. To do so, unlatch the clip that holds the cable clamp together, then
route all wires flat against the lower half of the clamp. Clamp the wires down, then secure the
clamp with the metal clip unlatched earlier.
Figure 2-4
Routing wires
through cable
clamp
Metal Clip
H
L
H
L
H
L
H
L
H
L
H
L
CH 1 CH 2 CH 3 CH 4 CH 5 OUT A
H
L
H
L
H
L
H
L
H L
H
L
CH 6 CH 7 CH 8 CH 9 CH 10 OUT B
Cable Clamp
Note : Plastic shield not shown.
Card Connections and Installation
2-9
Typical connecting schemes
The following paragraphs discuss typical connections for the scanner card.
Voltage connections
Figure 2-5 shows typical connections for voltage measurements. Note that all channels are
used in the 2-pole mode, and that up to 10 voltage sources can be switched with this configuration. This basic configuration can be used for the following types of measurements:
•
•
•
DCV
ACV
Frequency (voltage only)
All channels (1-10) can be used with this configuration.
HI
H
V
CH 1
LO
HI
L
Figure 2-5
Connections for
voltage scanning
H
V
CH 2
L
H
LO
HI
V
CH 3
L
LO
HI
H
V
CH 4
L
LO
HI
H
V
CH 5
L
H
OUT A
HI
LO
LO
L
To DMM
Input
H
HI
V
CH 6
L
H
CH 7
L
H
CH 8
LO
HI
V
LO
HI
V
L
H
CH 9
LO
HI
V
L
H
CH 10
L
H
OUT B
L
2000-SCAN Card
LO
HI
V
LO
Voltages
Under Test
2-10
Card Connections and Installation
Resistance connections
2-Pole connections
Figure 2-6 shows typical 2-pole resistor test connections. The 2-pole resistance configuration
can be used to test up to ten DUTs.
CH 1
H
L
CH 2
H
Figure 2-6
Typical connections for 2-wire
resistance scanning
L
Resistors
Under Test
H
CH 3
L
H
CH 4
L
H
CH 5
L
H
OUT A
L
To DMM
Input
H
CH 6
HI
LO
L
H
CH 7
L
H
CH 8
L
H
CH 9
L
H
CH 10
L
H
OUT B
L
2000-SCAN Card
Resistors
Under Test
Card Connections and Installation
2-11
4-Pole connections
Typical 4-pole resistance connections are shown in Figure 2-7. This general configuration can
be used with all channels to scan:
•
•
CH 1
H
L
CH 2
H
Figure 2-7
Typical connections for 4-wire
resistance scanning
4-wire resistance measurements.
4-wire RTD temperature measurements (Model 2001 and 2002 multimeters).
L
H
CH 3
L
Resistors
Under Test
H
CH 4
L
H
CH 5
L
H
OUT A
L
H
CH 6
L
H
CH 7
L
H
CH 8
L
H
CH 9
L
H
CH 10
L
H
OUT B
L
2000-SCAN Card
LO
HI
To DMM Sense
LO
HI
To DMM Input
2-12
Card Connections and Installation
Current measurements
Current shunts can be installed on the circuit board to allow indirect AC and DC current measurements to be made through channels 1 and 6 only. The following paragraphs discuss installing current shunts and the basic methods used to determine currents.
CAUTION
Board mounted current shunt resistors can be installed only for channels 1
and 6. A channel that has been modified with a current shunt resistor should
not be used for voltage or resistance measurements.
Current shunt locations
Figure 2-8 shows the locations for the user-installable current shunts. Location R145 is for
channel 1 and R146 is for channel 6.
Figure 2-8
Current shunt locations
R145 (Channel 1 shunt)
R146 (Channel 6 shunt)
CH 1 CH 2 CH 3 CH 4 CH 5 OUT A
H
L
H
L
H
L
H
L
H
L
H
L
CH 6 CH 7 CH 8 CH 9 CH 10 OUT B
H
L
H
L
H
L
H
L
H L
H
L
Recommended current shunt values
Hole spacing on the circuit board is intended for 1/4W resistors. The resistance value will depend on the current you intend to measure; 1kΩ resistors should be optimum for many applications. A 1kΩ resistor will allow you to switch currents up to 15mA without exceeding the power
rating of the resistor.
For larger currents, decrease the shunt value. Conversely, the shunt value can be increased for
smaller currents.
CAUTION
Do not exceed the maximum card signal levels:
• DC signals: 110V DC, 1A switched, 30 VA maximum.
• AC signals: 125V AC rms or 175V AC peak, 1A switched, 62.5 VA
maximum.
Card Connections and Installation
2-13
Board cleaning
NOTE
Failure to observe the following precautions may result in degraded card
performance.
When soldering resistors, be sure not to touch areas not associated with resistor installation
or spread flux around to other areas of the circuit board. Use solder with an OA (organic activated) flux. The circuit board should be thoroughly cleaned with pure water after soldering to
remove all contaminants. After cleaning with water, swab the area with pure methanol, then
allow the board to dry for several hours in a 50°C environment before use.
Current measurements
Even with the current shunts installed, you cannot make direct current measurements with the
scanner card. Instead, you must close the channel to be measured, and measure the voltage
across the shunt. The current can then be calculated as follows:
Where: I = current being determined
V= voltage measured by multimeter
R= shunt resistance value
Instead of manually calculating current, set up a Model 2000/2001/2002 mX + b math calculation function. (Here, m = 1/R and b = 0.). The multimeter will then display the actual current
value. Refer to the multimeter manuals for details on using math functions.
2-14
Card Connections and Installation
Current connections
Figure 2-9 shows typical connections for measuring currents using the Model 2000-SCAN
with current shunts installed. As noted previously, only channels 1 and 6 have current shunts
installed, and this configuration can be used to scan the following:
•
•
H
Figure 2-9
Current connections
DC current
AC current
CH 1
L
AC or DC
Current
H
CH 2
A
L
H
CH 3
L
H
CH 4
L
H
CH 5
L
H
OUT A
To DMM
Input
L
H
CH 6
L
AC or DC
Current
H
CH 7
A
L
H
CH 8
L
H
CH 9
L
H
CH 10
L
H
OUT B
L
2000-SCAN Card
Note: Current shunts must be
installed for channels
1 and 6.
Card Connections and Installation
2-15
Card installation and removal
This paragraph explains how to install and remove the Model 2000-SCAN card assembly
from the Model 2000 Multimeter.
WARNING
NOTE
Installation or removal of the Model 2000-SCAN should be performed only
by qualified service personnel. Failure to recognize and observe standard
safety precautions could result in personal injury or death.
To prevent contamination to the scanner card that could degrade performance, handle the card assembly only by the card edges and covers.
Wiring connections must made before installing the scanner card. See Section 2 “Typical connecting schemes” for wiring details.
2-16
Card Connections and Installation
Scanner Card Installation
Perform the following steps and refer to Figure 2-10 to install the card assembly in the
multimeter:
WARNING
Turn off power to all instrumentation (including the multimeter) and disconnect all line cords. Make sure all power is removed and any stored energy in
external circuitry is discharged.
Figure 2-10
Card installation
Unlock card
Ejector Arms (2)
Lock card
Note: Card installation in a Model 2001/2002
is shown. For installation in Model 2000,
turn card over.
1.
2.
3.
4.
Remove the cover plate from the OPTION SLOT on the rear panel of the multimeter. To
Do so, pry out the two fasteners, then remove the Cover plate.
Slide the card edges into the guide rails inside the multimeter (solder side up for Model
2001/2002, component side up for Model 2000).
With the ejector arms in the unlocked position, carefully push the card all the way forward until the arms engage the ejector clips. Push both arms inward to lock the card into
the multiMeter.
After installation, connect the output leads to the multimeter as discussed below.
Card Connections and Installation
2-17
Output connections to multimeter
After installation, connect the scanner card output leads to the multimeter rear panel jacks as
follows:
•
For 2-pole operation, connect OUT A HI (red) to INPUT HI, and connect OUT A LO
(black) to INPUT LO. See Figure 2-11.
Figure 2-11
2-pole output
connections
Input HI
Input LO
Out A
HI (Red)
Out A
LO (Black)
Note: Card installation in a Model 2001/2002
is shown. For installation in Model 2000,
turn card over.
NOTE
Be sure to select the rear inputs with the multimeter front panel INPUTS switch when
using the scanner.
2-18
Card Connections and Installation
•
For 4-pole operation, connect OUT A HI (red) to INPUT HI, and connect OUT A LO
(black) to INPUT LO. Also connect OUT B HI (red) to SENSE HI, and connect OUT B
LO (black) to SENSE LO. See Figure 2-12.
Figure 2-12
4-pole output
connections
Input HI
Input LO
Sense HI
Out A
HI (Red)
Out B
HI (Red)
Sense LO
Out B
LO (Black)
Out A
LO (Black)
Note: Card installation in a Model 2001/2002
is shown. For installation in Model 2000,
turn card over.
Scanner card removal
Follow the steps below to remove the scanner card from the multimeter:
WARNING
1.
2.
3.
Turn off power to all instrumentation (including the multimeter) and disconnect all line cords. Make sure all power is removed and any stored energy in
external circuitry is discharged.
Unlock the card by pulling the latches outward.
Carefully slide the card out of the multimeter.
If the multimeter is to be operated without the scanner card installed, install the cover
plate over the OPTION SLOT.
3
Operation
3-2
Operation
Introduction
This section contains detailed information on front panel and IEEE-488 bus operation of the
Model 2000-SCAN. The information in this section is organized as follows:
Signal limitations — Summarizes the maximum signals that can be applied to the Model
2000-SCAN.
Scanner card detection — Discusses how the scanner card is detected and how to determine
whether or not the card is installed with a bus command.
Model 2000 front panel scanner controls and IEEE-488 bus scanner commands — Gives
an overview of the Model 2000 Multimeter front panel controls and corresponding IEEE-488
bus commands used to control the scanner card.
IEEE-488 bus scanner commands — Summarizes bus commands necessary to control the
scanner card by either the Model 2000 or Model 2001/2002 Multimeters.
Model 2001/2002 front panel scanner controls and IEEE-488 bus scanner commands —
Gives and overview of the Model 2001/2002 Multimeter front panel controls and corresponding
IEEE-488 bus commands used to control the scanner card.
RTD temperature measurements — Provides detailed information on using RTD probes
when scanning (Model 2001/2002).
Typical applications — Discusses typical applications for the Model 2000-SCAN.
Measurement considerations — Discusses a number of measurement considerations that
should be taken into account when using the scanner.
NOTE
Before using the Model 2000-SCAN scanner card, you should be thoroughly familiar with the operation of the Model 2000 /2001/2002 Multimeter. See the multimeter manual for details.
Operation
3-3
Signal limitations
CAUTION
To prevent damage to the Model 2000-SCAN, do not exceed the maximum
signal level specifications of the card.
Relay input signal limitations
Channels 1-10 are all relay inputs. To prevent over-heating or damage to the relays, never
exceed the following maximum signal levels for these channels:
DC signals: 110V DC, 1A switched, 30VA (resistive load).
AC signals: 125V rms or 175V AC peak, 1A switched, 62.5VA (resistive load).
3-4
Operation
Scanner card detection
Power-up detection
The scanner card is detected only at power-on. If the card is plugged in after the power is
turned on, the card will not be recognized as being present by the multimeter.
CAUTION
Plugging in the scanner card with power turned on may result in damage to
both the Model 2000-SCAN and the multimeter.
If the card is not present at power-on, scanner bus commands or queries will generate a “Missing hardware error”, and front panel operations pertaining to the scanner will inform you that no
scanner is present.
Scanner option bus query
*OPT? is an IEEE 488.2 common query which will allow you determine whether or not a
scanner card is installed. The response to this query indicates whether or not a scanner card is
present as follows:
•
•
0: Scanner not installed.
200X-SCAN: Scanner installed. (The Model 2000 does not distinguish among scanner
cards.)
Refer to Model 2000/2001/2002 manuals for more details on using the *OPT? query.
Operation
3-5
Model 2000 Multimeter front panel scanner controls
and SCPI scanner commands
The following paragraphs give an overview of the various Model 2000 Multimeter front panel
controls and corresponding SCPI commands used with the Model 2000-SCAN.
Closing channels
Front Panel
Use the front panel CLOSE key to close specific channels as follows:
1.
From the normal display, press the CLOSE key. The instrument will display the
following:
CLOSE CHAN: 01
2.
Use the
ENTER.
,
, ▲ and ▼ keys to select the channel you wish to close, then press
The number of the closed channel will be displayed on the front panel along with normal
readings. Selecting a different channel from the one presently closed will cause the
closed channel to open and allow a settling time before closing the selected channel.
3.
The
and
keys alone will also close the channels. Press the
the channel annunciator you wish closed appears on the display.
and
keys until
Remote interface
Use the :ROUTe:CLOSe command to close the desired channel. For example, if you wish to
close channel 4, use the following command:
PRINT #1, "output 16; :route:close (@4)"
Use the :ROUTe:MULTiple:CLOSe command to close multiple channel. For example, if you
wish to close channels 1, 3 and 5, use the following command:
PRINT #1, "output 16; :route:multiple:close (@1,3,5)"
Note that closing channel 11 selects the 4-pole operating mode.
Opening channels
Front Panel
Use the front panel OPEN key to open all of the card channels.
3-6
Operation
Remote interface
Use the :ROUTe:OPEN:ALL command to open all of the channels. The command is as
follows:
PRINT #1, "output 16; :route:open:all"
Use the :ROUTe:MULTiple:OPEN command to open specified channels. For example, if you
wish to open channels 1, 3 and 5, use the following command:
PRINT #1, "output 16; :route:multiple:open (@1,3,5)"
Note that opening channel 11 selects the 2-pole operating mode.
Selecting measurement function
This section describes how to select a specific measurement function for an internal channel.
1.
2.
Use the
and
keys to select the desired channel.
Select the desired measurement function with the keys on the front panel. The various
measurement functions available are:
DCV: DC volts
ACV: AC volts
Ω2W: 2-wire ohms
Ω4W: 4-wire ohms (channels 1-5)
FREQ: frequency
PERIOD: period
TEMP: simulated temperature
CONT: continuity
: diode test
Configuring scan parameters
This section details how to select internal scanning and how to configure the scan parameters.
Front Panel
Use the SHIFT-CONFIG keys to select the scan type and configure the scan parameters.
1.
Press SHIFT then CONFIG. The instrument will display the following prompt for internal scanning:
TYPE: INT
Use the ▲ or ▼ key if EXT is displayed. Then press ENTER.
2.
The following message will be displayed:
MIN CHAN: 1
Use the ▲ and ▼ keys to select the channel at which the scanning will begin, then press
ENTER.
3.
The unit will then display the following message:
MAX CHAN: 10
Operation
3-7
Use the
.
, ▲, and ▼ keys to select the channel at which the scanning will stop,
then press ENTER.
4.
The instrument will then display the following message:
TIMER? OFF
Use the
or
key to select the ON option if desired, then press ENTER. Select the
scan time when prompted, then press ENTER:
00H:00M:01.000S
5.
The unit will then display the following message:
RDG CNT: 0010
Use the
.
, ▲, and ▼ keys to select the desired number of readings of the selected list
to be taken and stored by the instrument. Then press ENTER.
The instrument will store in memory the number of readings specified with RDG CNT. After
the scanning has been completed, these readings can be accessed by pressing the RECALL key
on the front panel and then using the
.
, ▲, and ▼ keys to scroll through the stored
readings.
6.
The following are the options to start the scanning:
STEP — Pressing the STEP key on the front panel will direct the instrument to begin scanning at Channel 1 and scan the number of channels specified with RDG CNT. It will store the
same number of readings.
TRIG — Pressing the TRIG key on the front panel will direct the instrument to begin scanning at the present channel setting and scan the number of channels specified with RDG CNT.
It will store the same number of readings.
SCAN — Pressing the SCAN key on the front panel will direct the instrument to scan through
the channels specified with MIN CHAN and MAX CHAN and store the number of readings
specified by RDG CNT.
7.
Pressing EXIT will clear the current readings and reset the channel to Channel 1.
Remote interface
Use the :ROUTe:SCAN:LSELect command to select internal or external scanning. For example, to select internal scanning use the following command:
PRINT #1, "output 16; :route:scan:lselect internal"
If you have selected internal, use the following command to set the list of channels to be
scanned:
PRINT #1, "output 16; :route:scan[:internal] (@scan list)"
For example, to scan channels 1 through 10 inclusively:
PRINT #1, "output 16; :route:scan[:internal] (@1:10)"
3-8
Operation
SCPI scanner commands
Table 3-1 summarizes commands that control scanner operations over the remote interface.
For more detailed information on these and other bus commands, refer to the multimeter
manuals.
The commands and comments in italics are valid only when the Model 2000-SCAN card is
installed in a Model 2001 or Model 2002 Multimeter.
Operation
3-9
Table 3-1
Summary of SCPI scanner commands
Command
Description
:ROUTe
:CLOSE <list>
:STATe?
:OPEN <list>|ALL
:ALL
:MULTiple
:CLOSE <list>
:STATe?
:OPEN <list>
:SCAN
[:INTernal] <scan list>
:FUNCtion <list>,<function>
:EXTernal <scan list>
:LSELect NONE | INTernal | EXTernal
Route subsystem.
Close channels.
Return all closed channels.
Open channels.
Open any closed channels.
Multiple channel commands:
Close specified channels (1 thru 11).
Query closed channels.
Open specified channels.
Scanning commands.
Program internal scan list.
Program channel functions.
Program external scan list.
Select scan list.
[:SENSe[1]]
:FUNCTion <function list>
:ALTernate[1]
:SAVe
:RECall
Sense subsystem
Select measurement function.
Program alternate function.
Save alternate function.
Recall alternate function.
The INT or EXT <function> parameter is
one of the following:
VOLTage:DC
VOLTage:AC
TEMPerature
FREQuency
RESistance
FRESistance
RJUNctionX
NONE
ALTernate[1]
DC volts
AC volts
Temperature
Frequency
2-wire resistance
4-wire resistance
Reference junction (X=1 to 5)
No function (skips listed channel during scan.)
Alternate function
Notes:
1. The :ROUT:SCAN:LSEL command is coupled to the :ROUT:SCAN:INT command. When the
:ROUT:SCAN:INT command is executed, the :ROUT:SCAN:LSEL parameter will be set to INTernal.
2. Upper-case letters indicate short form of commands.
3. Brackets indicate optional command and should not be used when sending commands to instrument.
4. When sending SCPI commands, be sure to include a space character between each command and
parameter.
3-10
Operation
Model 2001/2002 front panel scanner controls and
SCPI scanner commands
The following paragraphs give an overview of the various Model 2001/2002 front panel controls and corresponding SCPI commands use to control the Model 2000-SCAN scanner card
when installed in a Model 2001/2002 Multimeter.
CAUTION
Damage may occur because break-before-make operation for channels 5 and
10 cannot be guaranteed when the high-speed scanning modes of the Model
2001/2002 Multimeter are selected.
Closing channels
Front panel
Use the front panel CHAN key to close specific channels as follows:
1.
From normal display, press the CHAN key. The instrument will display the following
menu:
CHANNEL SELECTION
CLOSE-CHANNEL
OPEN-ALL-CHANNELS
2.
Select CLOSE-CHANNEL, then press ENTER. The Model 2001/2002 will display the
following prompt:
3.
Use the cursor and range keys to select the channel you wish to close (1-10), then press
ENTER. Any previously closed channel will open, and the selected channel will close.
ENTER CHANNEL# 00 (1-10)
NOTE
Once a channel is closed, use the
or
key to manually scan through channels.
Also, you can use the NEXT display to view three successive channels simultaneously.
Remote interface
Use the :ROUT:CLOSE command to close the desired channel. For example, assume you
wish to close channel 3. The following command would be used:
PRINT #1, "output 16; :rout:close (@3)"
Operation
3-11
Opening channels
Front panel
Use the front panel CHAN key to open any closed channels as follows:
1.
Press the CHAN key. The instrument will display the following menu:
CHANNEL SELECTION
CLOSE-CHANNEL
2.
OPEN-ALL-CHANNELS
Select OPEN-ALL-CHANNELS, then press ENTER. The closed channel will open
immediately.
Remote interface
Use the :ROUT:OPEN command to open the closed channel. For example, the following
command would be used to open channel 3:
PRINT #1, "output 16; :rout:open (@3)"
(You can also use :ROUT:OPEN:ALL or :ROUT:OPEN ALL to open channels.)
3-12
Operation
Scanning channels
Scanner channels are scanned by configuring scan channels and programming the Model
2001 or 2002 to perform a scan. The following paragraphs outline step-by-step procedures for
performing basic scanning from the front panel and over the IEEE-488 bus.
Front panel scanning
Step 1: Configure channels
Use CONFIG-CHAN to select the measurement functions for each of the scanner channels
as follows:
1.
Press CONFIG-CHAN. The instrument will display the following menu:
CONFIGURE CHANNELS
INTERNAL-CHANS
2.
EXTERNAL-INPUTS
Select INTERNAL-CHANS, then press ENTER. The multimeter will display the following menu:
SET INTERNAL CHANS
1=DCV
3.
4.
5.
6.
7.
2=DCV
3=DCV
4=DCV
5=DCV
Using the cursor keys, select the desired channel (press the right cursor key to display
channels 6 through 10).
Using the range keys, select the desired measurement function: DCV, ACV, Ω2W, Ω4W,
FRQ, TMP, ALT, --- (None).
Repeat steps 3 and 4 for each of the channels you wish to scan. NOTE: Select --- (none)
to omit a channel from the scan list.
After selecting all measurement functions, press ENTER.
Press EXIT to return to normal display.
Step 2: Configure and start scan
Configure the scan as follows:
1.
Press CONFIG-SCAN. The Model 2001/2002 will display the following:
SCAN OPERATION
INTERNAL
2.
3.
EXTERNAL
Select INTERNAL, then press ENTER.
Press SCAN, and follow the prompts to configure scanning. See the following paragraphs for details.
Operation
3-13
Using SCAN to configure scan parameters
Once the internal or external scan list is enabled, you use the SCAN key to configure scan
count, scan interval, and enable buffer storage. The steps below outline the basic procedure for
using the SCAN key to configure internal scanner operation.
1.
From normal display, press CONFIG-SCAN. The instrument will display the following:
SCAN OPERATION
INTERNAL
EXTERNAL
2.
3.
Select INTERNAL, then press ENTER.
Press SCAN. The unit will display the following message:
4.
Using the range and cursor keys, select the number of scan sequences, then press
ENTER. The instrument will display the following:
SCAN COUNT = 00010
USE SCAN TIMER?
YES
5.
NO
If you do not wish to use the scan timer (interval between scans), select NO, then press
ENTER, and go on to step 7. If you wish to use and program the interval between scans,
select YES, then press EN-TER. The instrument will display the following:
INTRVL = 000002.500
6.
7.
Using the range and cursor keys, select the desired interval between scan sequences, then
press ENTER.
The instrument will then prompt you as to whether or not you wish to store data in the
buffer as follows:
DATA TO MEMORY?
NO
8.
9.
YES
To store scanned data in the buffer, select YES; otherwise choose NO, then press
ENTER.
If you elected to store data in memory, the instrument will prompt you as follows:
00100 RDGS TO BUFFER
Press ENTER to continue.
NOTE
10.
11.
Use CONFIG-STORE to program the number of readings to store.
Press ENTER to begin scanning at the following prompt:
Press ENTER to begin
0010 scans of 10 channels
12.
13.
The instrument will then scan using selected scanning parameters. If you elected to store
data in memory, the instrument will display the reading number on the bottom line of the
display as readings are stored.
After readings are stored, the following will be displayed:
SCAN COMPLETE
RECALL-DATA
14.
SCAN-AGAIN
EXIT
Select the desired operation, then press ENTER.
3-14
Operation
Remote interface scanning
Step 1: Program channel functions
Use :ROUT:SCAN:INT:FUNC to program functions for the selected channels. For example,
assume that you want to measure DC volts on channel 1, AC volts on channel 2, and 2-wire resistance on channel 3. The commands to do so are as follows:
PRINT #1, "output 16; :rout:scan:int:func (@1),'volt:dc'"
PRINT #1, "otuput 16; :rout:scan:int:func (@2), 'volt:ac'"
PRINT #1, "output 16; :rout:scan:int:func (@3), 'res'"
If, on the other hand, you wish to use the same function (DCV, for example) on all three channels, a single command would suffice:
PRINT #1, "output 16; :rout:scan:int:func (@1,2,3), 'volt:dc'"
Step 2: Program internal scan list and start scan
Use the :ROUT:SCAN:INT command to program a scan list (channels you wish to scan). For
example, assume that you wish to scan channels 1, 2, and 3. This scan list would be programmed
as follows:
PRINT #1, "output 16; :rout:scan:int (@1,2,3)"
Scanning will begin immediately when this command is sent.
To disable scanning, send the :ROUT:SCAN:LSEL NONE command:
PRINT #1, "output 16; :rout:scan:lsel none"
NOTE
The :ABORT command will abort the present scan in progress and reset the channel
list to the beginning. Depending on various trigger layer parameters, :ABORT may
also stop the scanning process.
Operation
3-15
Using the scanner with the buffer
The Model 2001 internal buffer can be used to store readings taken while using the scanner.
The following paragraphs outline the steps necessary for fundamental data storage of scanner
readings.
Step 1: Configure channel
1.
Press CONFIG-CHAN. The instrument will display the following:
CONFIGURE CHANNEL
INTERNAL-CHANS
2.
EXTERNAL-INPUTS
Select INTERNAL-CHANS. The Model 2001/2002 will display the following:
SET INTERNAL CHANNELS
1=DCV
3.
4.
2=DCV
3=DCV
4=DCV
5=DCV
Use the cursor and range keys to select channels and functions, then press ENTER when
you have set all functions.
Press EXIT to return to normal display.
Step 2: Configure buffer
1.
Press CONFIG-STORE. The unit will display the following:
CONFIG DATA STORE
BURST-MODE DATA GROUP CONTROL
CLEAR-ALL
2.
COUNT
FEED
Select COUNT, then press ENTER. The instrument will display the following:
SET BUFFER SIZE
ENTER-COUNT
3.
USE-TRIGGER-MODEL
Select ENTER-COUNT and press ENTER to view the following:
BUFFER SIZE = 00010
4.
5.
Using the cursor and range keys, select the number of readings to store. Usually, this
number will be the same as the number of channels you are scanning. For example, if
you are using all 10 scanner channels, select 10 readings.
Press ENTER to complete programming data storage; then EXIT to return to normal
display.
Step 3: Configure scan, perform scan, and recall readings
1.
From normal display, press CONFIG-SCAN. The instrument will display the following:
SCAN OPERATION
INTERNAL
2.
3.
EXTERNAL
Select INTERNAL, then press ENTER.
Press SCAN, then follow the prompts. See “Configuring scan parameters”.
3-16
Operation
RTD temperature measurements
RTD temperature measurements are possible when the Model 2000-SCAN card is installed
in the Model 2001 or Model 2002 Multimeter. The following paragraphs outline the procedures
for making temperature measurements from the front panel using the scanner. For more detailed
information on temperature measurements in general, refer to the multimeter manuals.
Step 1: Connect RTD probes
Connect RTD probes to the scanner using the basic resistance connections outlined in the
multimeter manual. For 4-wire probes, pair the connections as follows:
•
•
•
•
•
Channels 1 and 6: probe #1
Channels 2 and 7: probe #2
Channels 3 and 8: probe #3
Channels 4 and 9: probe #4
Channels 5 and 10: probe #5
Step 2: Select sensor type and units
1.
From normal display, press CONFIG-TEMP. The instrument will display the following:
CONFIG TEMPERATURE
SENSOR
2.
UNITS
SPEED
FILTER RESLN
Select SENSOR, then press ENTER. The following will be displayed:
TEMP SENSOR TYPE
RTD
3.
4-WIRE-RTD
THERMOCOUPLE
Select RTD or 4-WIRE-RTD as appropriate for the sensor type you are using, then press
ENTER. The instrument will display the following:
SET RTD TYPE
PT385
4.
5.
6.
PT3916
USER-RTD
Select the RTD type from among the displayed types, then press ENTER.
Press EXIT to return to the CONFIG TEMPERATURE menu.
Select UNITS, then press ENTER. The unit will display the following selections:
SET TEMP UNITS
DEG-C
7.
8.
9.
DEG-F
K
Choose the type of temperature units you desire to use: °F, °C, or K, then press ENTER.
Before exiting the temperature configuration menu, select speed, filter, and resolution
operating modes, if desired.
Press EXIT to return to normal display.
Operation
3-17
Step 3: Configure channels
10.
Press CONFIG-CHAN. The instrument will display the following:
CONFIGURE CHANNELS
INTERNAL-CHANS
11.
EXTERNAL-INPUTS
Select INTERNAL-CHANS. The Model 2001 will display the following:
SET INTERNAL CHANNELS
1=DCV
12.
13.
2=DCV
3=DCV
4=DCV
5=DCV
Use the cursor and range keys to select channels and functions. Set the function type to
TMP for all channels connected to RTD probes. Select --- (none) for channels without
probes connected.
Press ENTER to return to normal display.
Step 4: Configure scan and scan channels
1.
From normal display, press CONFIG-SCAN. The instrument will display the following:
SCAN OPERATION
INTERNAL
2.
3.
EXTERNAL
Select INTERNAL, then press ENTER.
Press SCAN, then follow the prompts.
3-18
Operation
Typical applications
Resistor testing
The Model 2000-SCAN can be used to test up to 10 resistors using 2-wire measurements, or
up to five resistors using 4-wire measurements. Such tests use the Model 2000 Ω2 and Ω4 resistance functions.
2-wire resistance tests
Figure 3-1 shows a typical test setup for making 2-wire resistance measurements. The Model
2000-SCAN card provides the switching function, while the resistance measurements are made
by a Model 2000 Multimeter. Since only 2-pole switching is required for this application, one
Model 2000-SCAN card can be used to switch up to 10 resistors.
Measurement accuracy can be optimized by minimizing residual resistance: make connecting
wires as short as possible and limit the number of connectors to minimize path resistance.
Another technique is to short one of the scanner channel inputs, close the shorted channel, and
then enable the multimeter REL feature to null out path resistance. Leave REL enabled for the
entire test.
Figure 3-1
2-wire resistance
test connections
2000-SCAN
1
HI LO
Out A
1
10
10
DMM Rear Panel
(Model 2001/2002 shown)
DUTs
(10)
A. Test Configuration
Ω
R
Multimeter
2000-SCAN
DUT
B. Simplified Equivalent Circuit
Operation
3-19
4-wire resistance tests
More precise measurements over a wider range of system and DUT conditions can be
obtained by using the 4-wire measurement scheme shown in Figure 3-2. Here, separate sense
leads from the Model 2000 Multimeter are routed through the scanner to the resistor under test.
The extra set of sense leads minimizes the effects of voltage drops across the test leads, greatly
reducing measurement errors with lower DUT resistances. Note, however, that an extra two
poles of switching are required for each resistor tested. For this reason, only five resistors can be
tested using this configuration.
Figure 3-2
4-wire resistance
test connections
2000-SCAN
Out A
HI
Sense
HI
1
1
5
5
DUTs
(5)
LO
DMM Rear Panel
(Model 2001/2002 shown)
6
Sense
LO
Out B
10
A. Test Configuration
HI
Sense HI
Ω
R
Sense LO
LO
2001
2000-SCAN
DUT
B. Simplified Equivalent Circuit
3-20
Operation
Combining 2-pole and 4-pole switching (Models 2001/2002)
The Model 2000-SCAN can combine 2- and 4-pole switching in various combinations. For
example, you might require 4-pole switching for only two resistors, while the remaining resistors could be tested using conventional 2-pole switching.
Figure 3-3 shows a test configuration using mixed 2-pole and 4-pole switching. Four-pole
switching is used only for device 1 (connected to channels 1 and 6) and device 2 (connected to
channels 2 and 7). Six more resistors are tested using 2-pole switching.
Figure 3-3
Combining 2-pole
and 4-pole
switching (Model
2001/2002)
2000-SCAN
Out A
HI
CH 1
LO
4-Pole
Connections
CH 2
Input
HI
Input
LO
CH 3
CH 4
Sense
HI
Sense
LO
DMM Rear Panel
(Model2001/2002
shown)
CH 5
Out B
HI
CH 6
LO
2-Pole
Connections
CH 7
CH 8
CH 9
CH 10
DUT's (8)
Measurement functions for each scanner channel are defined using the INTERNAL-CHANS
menu available by pressing CONFIG-CHAN (see “Using the scanner with the buffer”). Measurement functions for this test would be set up as follows:
Channels 1 and 2: Ω4W
Channels 3, 4, 5 and 8, 10: Ω2W
Note that functions cannot be defined for channels 6 and 7 with this application because these
channels are paired with channels 1 and 2 for 4-pole switching.
Operation
3-21
Current measurements
Although the Model 2000-SCAN is not intended for direct current measurements, on-card
shunt resistors can be installed for channels 1 and 6 to allow for indirect current measurements.
Figure 3-4 shows the typical configuration for current measurements. Refer to Section 2 of this
manual for specific information on recommended shunt resistors and their installation.
Figure 3-4
Connections for
current measurements
User-installed
Shunts
2000-SCAN
CH 1
A
HI Out A
LO
A
CH 6
DMM Rear Panel
(Model 2001/2002)
DUTs (2)
A. Test Configuration
User-installed
Shunt
A
V
DMM
2000-SCAN
DUT
B. Simplified Equivalent Circuit
The current through each shunt resistor can be calculated as follows:
Where: I = current being determined
V = voltage measured by multimeter
R = shunt resistance value
Instead of manually calculating current, set up a Model 2000/2001/2002 mX + b math calculation function. (Here, m = 1/R and b = 0.). The multimeter will then display the actual current
value. Refer to the multimeter Manuals for details on using math functions.
3-22
Operation
Measurement considerations
Many measurements made with the Model 2000-SCAN are subject to various effects that can
seriously affect low-level measurement accuracy. The following paragraphs discuss these effects
and ways to minimize them.
Path isolation
The path isolation is simply the equivalent impedance between any two test paths in a measurement system. Ideally, the path isolation should be infinite, but the actual resistance and distributed capacitance of cables and connectors results in less than infinite path isolation values
for these devices.
Path isolation resistance forms a signal path that is in parallel with the equivalent resistance
of the DUT, as shown in Figure 3-5. For low-to-medium device resistance values, path isolation
resistance is seldom a consideration; however, it can seriously degrade measurement accuracy
when testing high-impedance devices. The voltage measured across such a device, for example,
can be substantially attenuated by the voltage divider action of the device source resistance and
path isolation resistance, as shown in Figure 3-6. Also, leakage currents can be generated
through these resistances by voltage sources in the system.
Figure 3-5
Path isolation resistance
R DUT
R PATH
V
R IN
E DUT
DUT
Scanner
Card
R DUT = Source Resistance of DUT
E DUT = Source EMF of DUT
R PATH = Path Isolation Resistance
R IN = Input Resistance of Multimeter
DMM
Operation
3-23
R DUT
Figure 3-6
Voltage attenuation by path isolation resistance
E DUT
E OUT =
R PATH
E OUT
E DUT R PATH
R DUT + R PATH
Magnetic fields
When a conductor cuts through magnetic lines of force, a very small current is generated.
This phenomenon will frequently cause unwanted signals to occur in the test leads of a scanning
system. If the conductor has sufficient length, even weak magnetic fields like those of the earth
can create sufficient signals to affect low-level measurements. Two ways to reduce these effects
are: (1) reduce the lengths of the test leads, and (2) minimize the exposed circuit area. In extreme
cases, magnetic shielding may be required. Special metal with high permeability at low flux densities (such as mu metal) is effective at reducing these effects.
Even when the conductor is stationary, magnetically-induced signals may still be a problem.
Fields can be produced by various signals such as the AC power line voltage. Large inductors
such as power transformers can generate substantial magnetic fields, so care must be taken to
keep the switching and measuring circuits a good distance away from these potential noise
sources. At high current levels, even a single conductor can generate significant fields. These
effects can be minimized by using twisted pairs, which will cancel out most of the resulting
fields.
3-24
Operation
Electromagnetic interference (EMI)
The electromagnetic interference characteristics of the Model 2000 Multimeter comply with
the electromagnetic compatibility (EMC) requirements of the European Union (EU) directives
as denoted by the CE mark. However, it is still possible for sensitive measurements to be affected
by external sources. In these instances, special precautions may be required in the test setup.
Sources of EMI include:
•
•
•
•
Radio and television broadcast transmitters.
Communications transmitters, including cellular phones and hand-held radios.
Devices incorporating microprocessors and high-speed digital circuits.
Impulse sources as in the case of arcing in high-voltage environments.
The instrument, measurement leads, and other cables should be kept as far away as possible
from any EMI sources. Shielding measurement leads and the multimeter may reduce EMI to
acceptable levels. In extreme cases, a specially constructed screen room may be required to
sufficiently attenuate troublesome signals.
Many instruments incorporate internal filtering that may help reduce EMI effects. In some
cases, additional external filtering may be required. Keep in mind, however, that filtering may
have detrimental effects on the measurement.
Ground loops
When two or more instruments are connected together, care must be taken to avoid unwanted
signals caused by ground loops. Ground loops usually occur when sensitive instrumentation is
connected to other instrumentation with more than one signal return path such as power line
ground. As shown in Figure 3-7, the resulting ground loop causes current to flow through the
instrument LO signal leads and then back through power line ground. This circulating current
develops a small but undesirable voltage between the LO terminals of the two instruments. This
voltage will be added to the source voltage, affecting the accuracy of the measurement.
Figure 3-7
Power line
ground loops
Signal Leads
Instrument 1
Instrument 2
Instrument 3
Ground Loop
Current
Power Line Ground
Figure 3-8 shows how to connect several instruments together to eliminate this type of ground
loop problem. Here, only one instrument is connected to power line ground. Ground loops are
not normally a problem with instruments having isolated LO terminals. However, all instru-
Operation
3-25
ments in the test setup may not be de-signed in this manner. When in doubt, consult the manual
for all instrumentation in the test setup.
Figure 3-8
Eliminating
ground loops
Instrument 1
Instrument 2
Instrument 3
Power Line Ground
Keeping connectors clean
As is the case with any high-resistance device, the integrity of connectors can be compromised if they are not handled properly. If connector insulation becomes contaminated, the insulation resistance will be substantially reduced, affecting high-impedance measurement paths.
Oils and salts from the skin can contaminate connector insulators, reducing their resistance.
Also, contaminants present in the air can be deposited on the insulator surface. To avoid these
problems, never touch the connector insulating material. In addition, the scanner card should be
used only in clean, dry environments to avoid contamination.
If the connector insulators should become contaminated, either by inadvertent touching, or
from air-borne deposits, they can be cleaned with a cotton swab dipped in clean methanol. After
thoroughly cleaning, they should be allowed to dry for several hours in a low-humidity environment before use, or they can be dried more quickly using dry nitrogen.
4
Service
Information
4-2
Service Information
WARNING
The information in this section is intended only for qualified service personnel. Some of the procedures may expose you to hazardous voltages that could
result in personal injury or death. Do not attempt to perform these procedures unless you are qualified to do so.
Introduction
This section contains information necessary to service the Model 2000-SCAN scanner card
and is arranged as follows:
Handling and cleaning precautions — Discusses handling precautions and methods to
clean the card should it become contaminated.
Performance verification — Covers the procedures necessary to determine if the scanner
card meets stated specifications.
Special handling of static-sensitive devices — Reviews precautions necessary when handling static-sensitive devices.
Principles of operation — Briefly discusses circuit operation.
Troubleshooting — Presents some troubleshooting tips for the Model 2000-SCAN including
relay replacement precautions.
Service Information
4-3
Handling and cleaning precautions
Because of the high-impedance areas on the Model 2000-SCAN, care should be taken when
handling or servicing the card to prevent possible contamination. The following precautions
should be observed when servicing the card.
Handling precautions
•
•
•
•
•
•
Handle the card only by the edges and shields.
Do not touch any board surfaces or components not associated with the repair.
Do not touch areas adjacent to electrical contacts.
When servicing the card, wear clean cotton gloves.
Do not store or operate the card in an environment where dust could settle on the circuit
board.
Use dry nitrogen gas to clean dust off the board if necessary.
Soldering precautions
Should it become necessary to use solder on the circuit board, observe the following
precautions:
•
•
•
•
Use an OA-based (organic activated) flux, and take care not to spread the flux to other
areas of the circuit board.
Remove the flux from the work areas when the repair has been completed. Use pure
water along with clean cotton swabs or a clean, soft brush to re-move the flux.
Once the flux has been removed, swab only the repaired area with methanol, then blow
dry the board with dry nitrogen gas.
After cleaning, the card should be allowed to dry in a 50°C low-humidity environment
for several hours before use.
4-4
Service Information
Performance verification
The following paragraphs discuss performance verification procedures for the Model
2000-SCAN, including path resistance, contact potential, and isolation.
NOTE
Contamination will degrade the performance of the card. To avoid contamination,
always grasp the card by the side edges and covers. Do not touch connector insulators, board surfaces, or components.
Failure of any performance verification test may indicate that the scanner card is contaminated. See Section 4 “Handling and cleaning precautions” for information on
cleaning the card.
Environmental conditions
All verification measurements should be made at an ambient temperature between 18° and
28°C, and at a relative humidity of less than 70%.
Recommended equipment
Table 4-1 summarizes the equipment necessary for performance verification, along with an
application for each item.
Service Information
4-5
Scanner card connections
Jumper wires or connecting cables can simply be hard-wired directly to the screw terminals
of the Model 2000-SCAN. Detailed connection information is provided in Section 2.
Table 4-1
Recommended verification equipment
Description
Model/part
Specifications
Multimeter
Keithley 2001
20Ω; 72ppm
Electrometer with
voltage source
Sensitive Digital
Voltmeter
Triax cable (unterminated)
Low-thermal cable
#22AWG solid
copper wire
#22AWG Tefloninsulated stranded
wire
Keithley 617
Application
Keithley 182
Control card, measure path
resistance
10pA, 100pA; 1.6% Path isolation
100V source; 0.2%
3mV; 60ppm
Contact potential
Keithley 7025
—
Path isolation
Keithley 1484
—
—
—
Contact potential
Path resistance
—
—
Path isolation
4-6
Service Information
Path resistance tests
Perform the following steps to verify that the path resistance of each channel is with specified
values.
1.
NOTE
2.
3.
4.
5.
6.
7.
8.
9.
Connect the HI and LO terminals of all 10 channel inputs together to make one common
terminal using #22AWG solid copper jumper wires (see Figure 4-1).
Make sure that all jumper wires are clean and free of oxides.
Connect the output cables to OUT A HI and LO, as shown in Figure 4-1.
With the power off, install the scanner card in the Model 2001 Multimeter.
Turn on the Model 2001, and allow it to warm up for one hour before proceeding.
Select the Ω2W function and the 20Ω range on the Model 2001.
Temporarily connect a second set of output leads, identical in length and type to the leads
connected to the scanner card output, to the Model 2001 rear panel HI and LO INPUT
jacks. Be sure to select the rear panel terminals with the front panel INPUT switch.
Short the free ends of the temporary leads together, and allow the reading to settle.
Enable the Model 2001 REL mode after settling, and leave REL enabled for the remainder of the path resistance tests.
Disconnect the temporary leads from the multimeter, and connect the output leads from
the scanner card to the rear panel HI and LO INPUT jacks (see Figure 4-1).
Close channel 1 as follows;
A. From normal display, press CHAN. The instrument will display the following:
CHANNEL SELECTION
CLOSE-CHANNEL
OPEN-ALL-CHANNELS
B. Select CLOSE-CHANNEL, then press ENTER. The Model 2001 will display the
following:
ENTER CHAN#01 (1-10)
C. Using the range and cursor keys, select channel 01, then press ENTER.
D. Press EXIT to return to normal display.
Service Information
10.
11.
4-7
Note the resistance reading on the Model 2001. Verify that the reading is <2Ω.
Repeat steps 9 and 10 for channels 2-9. Verify that the path resistance for each channel
is as follows:
channels 1-10: <2Ω.
12.
Figure 4-1
Connections for
path resistance
checks
After completing the tests, turn off the Model 2001 power, remove the scanner card, and
remove all jumper wires (leave HI and LO shorted for each channel if you intend to perform contact potential tests).
Jumper HI and LO
of all 10 Channels
Input
HI
Channel 1
Input
LO
HI
LO
Channel 2-4
HI
Channel 5
LO
HI
OUT A
LO
HI
LO
4-Pole
HI
LO
Channel 7-9
HI
Channel 10
LO
Channel 6
Model 2000-SCAN
2-Pole
OUT B
DMM Rear Panel
(Model 2001/2002
shown)
4-8
Service Information
Contact potential tests
These tests check the EMF (contact potential) generated by each relay contact pair (HI and
LO) for each channel. The tests use a sensitive digital voltmeter (Model 182) to measure the contact potential.
Perform the following procedure to check contact potential of each channel.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Connect 1” #22AWG copper jumper wires between the HI and LO terminals of each
channel input (see Figure 4-2).
Connect the Model 182 to OUT A HI and LO using the low-thermal cable (see Figure
4-2).
With the power off, install the scanner card in the Model 2001 Multimeter.
Turn on the Model 2001 and the Model 182 Sensitive Digital Voltmeter. Allow the Model
182 to warm up for two hours before measurement.
Select the 3mV range on the Model 182.
Select the DCV function on the Model 2001.
Using the CHAN key, close channel 1 (see Section 4 “Path resistance tests” for
procedure).
Verify that the Model 182 reading is <1µV.
Repeat steps 7 and 8 for all 10 channels.
After completing all measurements, turn off the Model 2001 power, remove the scanner
card, and disconnect all jumpers and test leads.
Figure 4-2
Connections for
contact potential
tests
Model 1484
Low Thermal Cable
(Unterminated)
KEITHLEY
Connect bare copper jumpers between
HI and LO of each channel
Channel 1
182 SENSITIVE DIGITAL VOLTMETER
Model 182
HI
LO
Channel 2-4
HI
Channel 5
LO
HI
OUT A
LO
HI
OUT B
LO
4-Pole
Channel 6
HI
LO
Channel 7-9
HI
Channel 10
LO
Model 2000-SCAN
2-Pole
Service Information
4-9
Isolation tests
These tests check the leakage resistance (isolation) between all HI and LO terminals and from
HI and LO terminals to chassis ground. In general, the test is performed by applying a voltage
(100V) across the terminals and then measuring the leakage current. The isolation resistance is
then calculated as R = V/I. In the following procedure, the Model 617 functions as a voltage
source and as an ammeter. In the V/I function, the Model 617 internally calculates the resistance
from the known voltage and current levels, and displays the resistance value.
Perform the following steps to check isolation:
1.
2.
3.
4.
5.
Connect a 4” length of Teflon-insulated #22AWG stranded wire to every HI and LO terminal on the scanner card (both inputs and outputs). Mark the free end of each wire so
you can identify wires when the scanner card is installed.
With the power off, install the scanner card in the multimeter.
Turn on the Model 2001 power.
Turn on the Model 617, and allow the unit to warm up for two hours for rated accuracy.
Select the Model 617 2pA range, and enable zero check and zero correct in that order.
Leave zero correct enabled for the entire procedure.
WARNING
6.
7.
8.
Figure 4-3
Connections for
same-channel
isolation tests
The following steps use high voltage (100V). Be sure to remove power from
the circuit before making connection changes.
Set the Model 617 voltage source for +100V, and select the 200nA current range. Make
sure the voltage source is still in standby.
Place the Model 617 in the V/I measurement function by pressing SHIFT OHMS.
With the Model 617 in standby, connect the electrometer to OUT A HI and LO terminals
of the scanner card, as shown in Figure 4-3.
Model 7025
Unterminated
Triax Cable
Banana to Banana Cable
Ground Link
Com
Removed
INPUT
HI
(Red)
V-Source LO
V-Source HI
Source V and
Measure V/I
Model 617
Unterminated to
Banana Cable
HI
LO
Channel 2-4
HI
Channel 5
LO
Channel 1
HI
OUT A
LO
4-Pole
HI
LO
Channel 7-9
HI
Channel 10
LO
Channel 6
Model 2000-SCAN
HI
OUT B
LO
2-Pole
4-10
Service Information
9.
10.
11.
12.
13.
14.
Figure 4-4
Connections for
channel-to-channel isolation tests
Close channel 1 using the CHAN key (see Section 4 “Path resistance tests” for details).
On the Model 617, disable zero check, and press OPERATE to source 100V.
After allowing the reading on the Model 617 to settle, verify that the reading is >1GΩ
(109Ω). This measurement represents the isolation resistance between the HI and LO terminals of channel 1.
Place the Model 617 in standby, and enable zero check.
Repeat steps 9 through 12 for channels 2 through 10. Be sure that the channel under test
is closed.
With the Model 617 voltage source in standby, connect the electrometer to the HI terminals of scanner card channels 1 and 2, as shown in Figure 4-4.
Banana to Banana Cable
Ground Link
Removed
Com
Model 7025
Unterminated
Triax Cable
INPUT
V-Source LO
V-Source HI
Source V and
Measure V/I
HI
(Red)
Model 617
Channel 1
HI
LO
Channel 2-4
Channel 5
Unterminated to
Banana Cable
HI
OUT A
LO
HI
LO
HI
LO
4-Pole
OUT B
2-Pole
HI
LO
Channel 7-9
Channel 6
Channel 10
HI
LO
Model 2000-SCAN
15.
16.
17.
18.
19.
20.
Close channel 1 using the CHAN key.
On the Model 617, disable zero check, and press OPERATE to source 100V.
After allowing the reading on the Model 617 to settle, verify that the reading is >1GΩ
(109Ω). This measurement represents the isolation resistance between the HI terminals
of channels 1 and 2.
Place the Model 617 in standby, and enable zero check.
Repeat steps 14 through 18 to measure isolation resistance between the channel 1 HI terminal and channels 3 through 10 HI terminals. Be sure that the electrometer is connected
to the HI terminals of the two channels being tested, and that channel 1 is closed.
Repeat steps 14 through 19 for the LO terminals of channels 1 through 10. Be sure the
electrometer is connected to the LO terminals of the two channels being tested, and that
channel 1 is closed.
Service Information
21.
Figure 4-5
Connections for
HI and LO terminal to chassis
ground isolation
tests
4-11
With the electrometer voltage source in standby, connect the electrometer to channel 1
HI and chassis ground, as shown in Figure 4-5.
Banana to Banana Cable
Ground Link
Removed
Com
Model 7025
Unterminated
Triax Cable
INPUT
V-Source LO
Model 617
V-Source HI
Source V and
Measure V/I
Unterminated to
Banana Cable
HI
(Red)
HI
LO
Channel 1
Channel 2-4
HI
LO
HI
OUT A
LO
Channel 5
HI
LO
Chassis Ground
4-Pole
OUT B
2-Pole
HI
Channel 6
LO
Channel 7-9
HI
LO
Channel 10
Model 2000-SCAN
22.
23.
24.
25.
26.
27.
Program the Model 2000 to close channel 1.
On the Model 617, disable zero check, and press OPERATE to source +100V.
After allowing the reading on the Model 617 to settle, verify that it is >1GΩ (109Ω).
Put the electrometer in standby, and enable zero check.
Repeat steps 21 through 25 for channels 2 through 10. One electrometer lead should be
connected to the HI terminal of the channel being testing, and the other lead should be
connected to chassis ground.
Repeat steps 21 through 26 for channels 1 through 10 LO terminals. One electrometer
lead should be connected to the LO terminal of the channel being tested, and the other
lead should be connected to chassis ground. In addition, channel 1 should be closed.
4-12
Service Information
Special handling of static-sensitive devices
CMOS and other high-impedance devices are subject to possible static discharge damage
because of the high-impedance levels involved. When handling such devices, use the precautions listed below.
NOTE
1.
2.
3.
4.
5.
In order to prevent damage, assume that all parts are static-sensitive.
Such devices should be transported and handled only in containers specially designed to
prevent or dissipate static build-up. Typically, these devices will be received in anti-static
containers made of plastic or foam. Keep these parts in their original containers until
ready for installation or use.
Remove the devices from their protective containers only at a properly grounded workstation. Also, ground yourself with an appropriate wrist strap while working with these
devices.
Handle the devices only by the body; do not touch the pins or terminals.
Any printed circuit board into which the device is to be inserted must first be grounded
to the bench or table.
Use only anti-static type de-soldering tools and grounded-tip soldering irons.
Service Information
4-13
Principles of operation
The following paragraphs discuss the basic operating principles for the Model 2000-SCAN,
and can be used as an aid in troubleshooting the card. The schematic drawing of the card is
shown on drawing number 2000-176, located at the end of Section 5 of this manual.
Block diagram
Figure 4-6 shows a simplified block diagram of the Model 2000-SCAN. Key elements
include the relay drivers and relays, as well as the power-up reset circuit. These various elements
are discussed in the following paragraphs.
Figure 4-6
Block diagram
To
Multimeter
Clock
Data
Strobe
Relay
Drivers
U101-U103
Relays
User Connections
K101-K111
Enable
Power-on
Reset
U104
+5V
Relay control
Card relays are controlled by serial data transmitted via the relay DATA line. A total of three
bytes are shifted in serial fashion into latches located in the card relay driver ICs. The serial data
is clocked in by the CLOCK line. As data overflows one register, it is fed out the Q’S line of the
register down the chain.
Once all three bytes have shifted into the card, the STROBE line is set high to latch the relay
information into the Q outputs of the relay drivers, and the appropriate relays are energized
(assuming the driver outputs are enabled, as discussed below). Note that a relay driver output
goes low to energize the corresponding relay.
Switching circuits
Relays K101 through K106 and K108 to K111 perform input switching, while K107 configures the card for 2-pole or 4-pole operation.
Power-on safeguard
A power-on safeguard circuit, made up of U104 and associated components, ensures that
relays do not change state on power-up and power-down. This circuit disables all relay actuation
during power-up and power-down periods by holding the OE (output enable lines) high during
these periods.
4-14
Service Information
Troubleshooting
Troubleshooting equipment
Table 4-2 summarizes recommended equipment for troubleshooting the Model 2000-SCAN.
Table 4-2
Recommended troubleshooting equipment
Description
Manufacturer and model
Application
Multimeter
Oscilloscope
Keithley 2000/2001
TEK 2243
DCV checks
View logic waveforms
Troubleshooting access
In order to gain access to the scanner card circuit board to measure voltages under actual
operating conditions, perform the following steps:
1.
2.
3.
Turn off the Model 2000 power, and disconnect the line cord and all other equipment.
If wires are connected to the scanner card, remove the scanner card from the multimeter.
Remove the Model 2000 cover as follows:
A. Remove the handle by rotating it to align the arrows on the handle mounting ears.
Pull out and remove the handle.
B. Remove the screws that secure the handle mounting ears, then remove the ears.
C. Remove the screws that attach the rear bezel to the case, then remove the bezel.
D. Remove the bottom screws that grounds the case to the chassis.
WARNING
4.
5.
6.
Be sure to install and tighten the grounding screws after replacing the cover.
E. Remove the cover by pulling it off towards the rear.
Disconnect any wires connected to the scanner card terminal blocks.
Install the scanner card in the multimeter.
Connect the line cord, and turn on the power to measure voltages (see following
paragraph).
Service Information
4-15
Troubleshooting procedure
Table 4-3 summarizes scanner card troubleshooting steps. Refer to the schematic diagram
and component layout drawings at the end of Section 5 for component locations.
WARNING
Lethal voltages are present within the Model 2000. Some of the procedures
may expose you to hazardous voltages. Observe standard safety precautions
for dealing with live circuits. Failure to do so could result in personal injury
or death.
CAUTION
Use care when removing relays from the PC board to avoid pulling traces
away from the circuit board. Before attempting to remove a relay, use an
appropriate de-soldering tool, such as a solder sucker, to clear each mounting
hole completely free of solder. Each relay pin must be free to move in its
mounting hole before removal. Also, make certain that no burrs are present
on the ends of the relay pins.
NOTE
To avoid contamination, which could degrade card performance, always handle the
card only by the side edges and covers. Do not touch edge connectors, board surfaces,
or components on the card. Also, do not touch areas adjacent to electrical contacts
on connectors.
Table 4-3
Troubleshooting procedure
Step
Item/component
Required condition
1
Digital ground P1034,
pin 1, 3, 5
P1034, pin 9
U101, pin 2
U101, pin 3
U101, pin 7
U101-U103, pins 10-18
All voltages referenced to digital
ground.
Card power supply voltage.
+5VDC
Serial clock pulses.
CLOCK pulses
Serial data pulses.
DATA pulses
End of relay update sequence.
STROBE pulse
Low when relay state High when relay is not changing
state. Relay driver outputs.
is changed.
2
3
4
5
6
Comments
5
Replaceable
Parts
5-2
Replaceable Parts
Introduction
This section contains replacement parts information, schematic diagram, and component layout drawing for the Model 2000-SCAN.
Parts list
A parts list for the scanner card is included in a table integrated with schematic diagram and
component layout drawing for the board. Parts are listed alphabetically in order of circuit
designation.
Ordering information
To place an order, or to obtain information concerning replacement parts, contact your
Keithley representative or the factory (see inside front cover for addresses). When ordering
parts, be sure to include the following information:
•
•
•
•
•
Card model number (2000-SCAN)
Card serial number
Part description
Circuit description, if applicable
Keithley part number
Replaceable Parts
5-3
Factory service
If the card is to be returned to Keithley Instruments for repair, perform the following:
•
•
•
•
NOTE
Call the Instruments Division Repair Department at 1-800-552-1115 for a Return Material Authorization (RMA) number.
Complete the service form at the back of this manual and include it with the card.
Carefully pack the card in the original packing carton.
Write ATTENTION REPAIR DEPT and the RMA number on the shipping label.
It is not necessary to return the Model 2000 Multimeter with the card.
Component layout and schematic diagram
A component layout drawing and schematic diagram are included on the following pages
integrated with the parts list for the Model 2000-SCAN.
5-4
Replaceable Parts
Model 2000-SCAN, parts list
Description
Keithley part
no.
Card Ejector
Clip, Strain Relief
Shield, Scanner Bottom
Shield, Scanner Top
Sleeved Banana Plug Test Lead
Strain Relief, Bottom
Strain Relief, Top
Strip, Polyurethane
FA-237
2001-351
2001-341
2001-342
CA-109
2001-344
2001-349
2001-345-1
C101-103, 105, 106
C107
CAP, .1UF,20%,50V, CERAMIC
CAP, 100UF, 20%, 25V, ALUM ELEC
C-365-.1
C-413-100
J1035,1036
CONN, FEMALE, 12 PIN
CS-768-12
K101-111
RELAY, MINATURE (DPDT) TQ2E-L2-5V
RL-155
P1034
CONN, FEMALE DUAL 16-PIN
CS-455
R134
R147
RES, 1K, 5%, 1/4W, COMPOSITION OR FILM
RES, 4.7K, 5%, 1/4W, COMPOSITION OR FILM
R-76-1K
R-76-4.7K
U101-103
U104
IC-536
IC, 8-BIT SERIAL-IN LATCH DRIVER, 5841A
IC, SUPPLY VOLTAGE SUPERVISOR, TL7705AC IC-602
Circuit desig.
A
Specifications
A-2
Specifications
GENERAL
10 Channels: 10 channels of 2-pole relay input.
All channels configurable to 4-pole.
Relay Type : Latching electro mechanical.
Actuation Time: <3.5ms.
CAPABILITIES: Multiplex one of ten 2-pole or one of five 4-pole signals into DMM.
INPUTS
Maximum Signal Level:
DC Signals: 110V DC, 1A switched, 30VA maximum (resistive load).
AC Signals: 125V AC rms or 175V AC peak, 100kHz maximum, 1A switched, 62.5VA maximum (resistive load).
Contact Life: >105 operations at maximum signal level; >108 operations cold switching.
Contact Resistance: <1Ω at end of contact life.
Contact Potential: <±500nV typical per contact, 1µV max.
<±500nV typical per contact pair, 1µV max.
Connector Type: Screw terminal, #22 AWG wire size.
Isolation Between Any Two Terminals: >109Ω, <75pF.
Isolation Between Any Terminal and Earth: >109 Ω, <150pF.
Common Mode Voltage: 350V peak between any terminal and earth.
Maximum Voltage Between Any Two Terminals: 200V peak.
Maximum Voltage Between Any Terminal and Mainframe Input LO: 200V peak.
ENVIRONMENTAL:
Operating Environment: Specified for 0°C to 50°C.
Specified to 80% R.H. at 35°C.
Storage Environment: –40°C to 70°C.
DIMENSIONS, WEIGHT: 21mm high × 72mm wide × 221mm deep (0.83 in. × 2.83 in. × 8.7 in.). Adds 0.4kg (10 oz.).
SCANNER CONFIGURATION:
Channel 1
HI
LO
Channel 2-4
Channel 5
HI
HI
LO
LO
HI
LO
4-Pole
Channel 6
HI
LO
Channel 7-9
Channel 10
HI
LO
Specifications subject to change without notice.
2-Pole
OUT A
OUT B
Index
B
O
Block diagram 4-13
Opening channels 3-5, 3-11
Operation 3-1
Ordering information 5-2
Output connections 2-7
Output connections to multimeter 2-17
C
Card configuration 2-4
Card connectors 2-5
Card Connections and Installation 2-1
Card installation and removal 2-15
Closing channels 3-5, 3-10
Component layout and schematic diagram 5-3
Configuring scan parameters 3-6
Connections 2-4
Contact potential tests 4-8
Current measurements 2-12, 3-21
D
Dressing leads 2-8
P
Parts list 5-2
Path isolation 3-22
Path resistance tests 4-6
Performance verification 4-4
Power option bus query 3-4
Power-on safeguard 4-13
Principles of operation 4-13
R
Radio frequency interference (RFI) 3-24
Recommended equipment 4-4
Relay control 4-13
Relay input signal limitations 3-3
Repacking for shipment 1-4
Replaceable parts 5-1
Resistance connections 2-10
Resistor testing 3-18
RTD temperature measurements 3-16
E
Environmental conditions 4-4
F
Factory service 5-3
Features 1-2
G
General Information 1-1
Ground loops 3-24
H
Handling and cleaning precautions 4-3
Handling precautions 1-4, 2-3, 4-3
I
Inspection for damage 1-4
Instruction manual 1-4
Isolation tests 4-9
K
Keeping connectors clean 3-25
M
Magnetic fields 3-23
Manual addenda 1-3
Measurement considerations 3-22
Model 2000 Multimeter front panel scanner
controls 3-5
Model 2001/2002 front panel scanner
controls 3-10
S
Safety Symbols and terms 1-3
Scanner card connections 4-5
Scanner card detection 3-4
Scanner card installation 2-16
Scanner card removal 2-18
Scanner option bus query 3-4
Scanning channels 3-12
SCPI scanner commands 3-5, 3-8, 3-10
Selecting measurement function 3-6
Service Information 4-1
Shipment contents 1-4
Signal limitations 3-3
Soldering precautions 4-3
Special handling of static-sensitive devices 4-12
Specifications 1-3, A-1
Switching circuits 4-13
T
Troubleshooting 4-14
Troubleshooting access 4-14
Troubleshooting equipment 4-14
Troubleshooting procedure 4-15
Typical applications 3-18
Typical connecting schemes 2-9
U
Unpacking and inspection 1-4
Using the scanner with the buffer 3-15
V
Voltage connections 2-9
W
Warranty information 1-2
Wiring procedure 2-6
Service Form
Model No. ___________________________ Serial No. _____________ Date __________
Name and Telephone No. ________________________________________________________
Company ______________________________________________________________________
List all control settings, describe problem and check boxes that apply to problem. _________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
❑ Intermittent
❑ Analog output follows display
❑ Particular range or function bad; specify
_______________________________
❑ IEEE failure
❑ Obvious problem on power-up
❑ Front panel operational ❑ All ranges or functions are bad
❑ Batteries and fuses are OK
❑ Checked all cables
Display or output (check one)
❑ Drifts
❑ Overload
❑ Unable to zero
❑ Will not read applied input
❑ Calibration only
❑ Certificate of calibration required
(attach any additional sheets as necessary)
❑ Unstable
❑ Data required
Show a block diagram of your measurement including all instruments connected (whether power is turned on or
not). Also, describe signal source.
Where is the measurement being performed? (factory, controlled laboratory, out-of-doors, etc.)_______________
__________________________________________________________________________________________
What power line voltage is used? ___________________ Ambient temperature? ________________________ °F
Relative humidity? ___________________________________________Other? __________________________
Any additional information. (If special modifications have been made by the user, please describe.)
__________________________________________________________________________________________
__________________________________________________________________________________________
Be sure to include your name and phone number on this service form.
Keithley Instruments, Inc.
28775 Aurora Road
Cleveland, Ohio 44139
Printed in the U.S.A.
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