Keithley 2000-SCAN-20 User manual

Model 2000-SCAN-20 Scanner Card
Instruction Manual
A GREATER MEASURE OF CONFIDENCE

Model 2000-SCAN-20 Scanner Card
Instruction Manual
©1997, Keithley Instruments, Inc.
All rights reserved.
Cleveland, Ohio, U.S.A.
Third Printing, July 2003
Document Number: 2000-20-901-01 Rev. C

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 2000-20-901-01).................................................... February 1998
Revision B (Document Number 2000-20-901-01)........................................................... June 1998
Revision C (Document Number 2000-20-901-01)............................................................ July 2003
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.

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 and follow all installation, operation, and maintenance information carefully before
using the product. Refer to the manual for complete product specifications.
If the product is used in a manner not specified, the protection provided by the product may be impaired.
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 equip-
ment 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 properly, 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.
Keithley products are designed for use with electrical signals that are rated Measurement Category I and Measurement Category
II, as described in the International Electrotechnical Commission (IEC) Standard IEC 60664. Most measurement, control, and
data I/O signals are Measurement Category I and must not be directly connected to mains voltage or to voltage sources with
high transient over-voltages. Measurement Category II connections require protection for high transient over-voltages often
associated with local AC mains connections. Assume all measurement, control, and data I/O connections are for connection to
Category I sources unless otherwise marked or described in the Manual.
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.
Operators of this product must be protected from electric shock at all times. The responsible body must ensure that operators
are prevented access and/or insulated from every connection point. In some cases, connections must be exposed to potential
human contact. Product operators 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.
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.
When installing equipment where access to the main power cord is restricted, such as rack mounting, a separate main input
power disconnect device must be provided, in close proximity to the equipment and within easy reach of the operator.
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
S
afety Precautions
5/03

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 screw is present, connect it to safety earth ground using the wire recommended in the user documentation.
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 symbol indicates a connection terminal to the equipment frame.
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 accord-
ing to instructions. If the board becomes contaminated and operation is affected, the board should be returned to the factory for
proper cleaning/servicing.
!

Table of Contents
1 General Information
Introduction ................................................................................ 1-2
Features ...................................................................................... 1-2
Manual addenda ......................................................................... 1-3
Safety symbols and terms .......................................................... 1-3
Specifications ............................................................................. 1-3
Unpacking and inspection .......................................................... 1-3
Inspection for damage ......................................................... 1-3
Handling precautions .......................................................... 1-4
Shipment contents ............................................................... 1-4
Instruction manual .............................................................. 1-4
Repacking for shipment ............................................................. 1-4
Optional accessories ................................................................... 1-5
2 Card Connections and Installation
Introduction ................................................................................ 2-2
Handling precautions ................................................................. 2-2
Connections ................................................................................ 2-3
Connection precautions ....................................................... 2-3
Card configuration .............................................................. 2-4
Card connectors .................................................................. 2-5
Typical connecting schemes ...................................................... 2-8
Voltage connections ............................................................ 2-8
Resistance connections ....................................................... 2-9
Current measurements ...................................................... 2-11
Card installation and removal .................................................. 2-14
Scanner card installation ................................................... 2-14
Output connections to multimeter ..................................... 2-16
Scanner card removal ........................................................ 2-17

3 Operation
Introduction ................................................................................ 3-2
Signal limitations ........................................................................ 3-2
Relay input signal limitations .............................................. 3-2
Scanner card detection ................................................................ 3-3
Power-up detection .............................................................. 3-3
Scanner option bus query .................................................... 3-3
Model 2000-20 multimeter front panel scanner controls and
SCPI scanner commands ......................................................... 3-4
Closing channels ................................................................. 3-4
Opening channels ................................................................ 3-5
Selecting measurement function ......................................... 3-5
Configuring scan parameters ............................................... 3-6
SCPI scanner commands ............................................................ 3-8
Typical applications .................................................................... 3-9
Resistor testing .................................................................... 3-9
Current measurements ....................................................... 3-11
Measurement considerations .................................................... 3-12
Path isolation ..................................................................... 3-12
Magnetic fields .................................................................. 3-13
Electromagnetic interference (EMI) .................................. 3-13
Ground loops ..................................................................... 3-14
Keeping connectors clean .................................................. 3-15
4 Service Information
Introduction ................................................................................ 4-2
Handling and cleaning precautions ............................................ 4-2
Handling precautions ........................................................... 4-2
Soldering precautions .......................................................... 4-3
Performance verification ............................................................ 4-3
Environmental conditions ................................................... 4-3
Recommended equipment ................................................... 4-4
Path resistance tests ............................................................. 4-4
Contact potential tests ......................................................... 4-6
Isolation tests ....................................................................... 4-7
Special handling of static-sensitive devices ............................. 4-10
Principles of operation .............................................................. 4-10
Block diagram ................................................................... 4-10
Relay control ..................................................................... 4-11
Switching circuits .............................................................. 4-11
Power-on safeguard ........................................................... 4-11

5 Replaceable Parts
Introduction ................................................................................ 5-2
Parts list ...................................................................................... 5-2
Ordering information ................................................................. 5-2
Factory service ........................................................................... 5-2
Component layout and schematic diagram ................................ 5-3
A Specifications

List of Illustrations
2 Card Connections and Installation
Figure 2-1 Model 2000-SCAN-20 simplified schematic ......................... 2-4
Figure 2-2 Card connectors ...................................................................... 2-5
Figure 2-3 Input and output connector terminal identification ................ 2-6
Figure 2-4 Connections for voltage scanning .......................................... 2-8
Figure 2-5 Typical connections for 2-wire resistance scanning .............. 2-9
Figure 2-6 Typical connections for 4-wire resistance scanning ............ 2-10
Figure 2-7 Current shunt locations ........................................................ 2-11
Figure 2-8 Current connections ............................................................. 2-13
Figure 2-9 Card installation ................................................................... 2-15
Figure 2-10 2-pole output connections .................................................... 2-16
Figure 2-11 4-pole output connections .................................................... 2-17
3 Operation
Figure 3-1 2-wire resistance test connections .......................................... 3-9
Figure 3-2 4-wire resistance test connections ........................................ 3-10
Figure 3-3 Connections for current measurements ................................ 3-11
Figure 3-4 Path isolation resistance ....................................................... 3-12
Figure 3-5 Voltage attenuation by path isolation resistance .................. 3-13
Figure 3-6 Power line ground loops ....................................................... 3-14
Figure 3-7 Eliminating ground loops ..................................................... 3-15
4 Service Information
Figure 4-1 Connections for path resistance checks .................................. 4-5
Figure 4-2 Connections for contact potential tests .................................. 4-6
Figure 4-3 Connections for same-channel isolation tests ........................ 4-7
Figure 4-4 Connections for channel-to-channel isolation tests ................ 4-8
Figure 4-5 Connections for HI and LO input-to-chassis ground
isolation tests .................................................................... 4-9
Figure 4-6 Block diagram ...................................................................... 4-11

List of Tables
2 Card Connections and Installation
Table 2-1 Input connector J1036 pin designations ................................. 2-7
Table 2-2 Output connector J1035 pin designations .............................. 2-7
3 Operation
Table 3-1 Summary of SCPI scanner commands ................................... 3-8
4 Service Information
Table 4-1 Recommended verification equipment .................................. 4-4
5 Replaceable Parts
Table 5-1 Model 2000-SCAN-20 parts list ............................................ 5-3

1
General
Information
General
Information

1-2 General Information
Introduction
This section contains general information about the Model 2000-SCAN-20 scanner card. The
Model 2000-SCAN-20 provides 20 channels of 2-pole relay switching. The channels can be
configured for 4-pole operation.
Section 1 is arranged in the following manner:
• Features
• Manual addenda
• Safety symbols and terms
• Specifications
• Unpacking and inspection
• Repacking for shipment
• Optional accessories
Features
The Model 2000-SCAN-20 is a scanner card designed to be installed in the Model 2000-20
Multimeter. (The Model 2000-SCAN-20 is not designed for the Models 2000 or 2010
Multimeters.)
Key features include:
• Twenty channels of 2-pole relay input.
• Channels configurable for 4-pole operation.
• Multiplex one of twenty 2-pole or one of ten 4-pole channels into a Model 2000-20
Multimeter.

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-20 specifications are found in Appendix A. These specifications are
exclusive of the multimeter specifications.
Unpacking and inspection
Inspection for damage
The Model 2000-SCAN-20 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 following handling precautions.
!

1-4 General Information
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-20 order:
• Model 2000-SCAN-20 Scanner Card
• Model 2000-20-901-00 Instruction Manual
• Test lead set for output connections (two red, two black)
• Additional accessories as ordered
Instruction manual
If an additional Model 2000-SCAN-20 Instruction Manual is required, order the manual
package, Keithley part number 2000-20-901-00. The manual package includes an instruction
manual and any pertinent addenda.
Repacking for shipment
Should it become necessary to return the Model 2000-SCAN-20 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.

General Information 1-5
Optional accessories
The following accessories are available for use with the Model 2000-SCAN-20 scanner card:
•
Models 2000-MTC-2 and 2000-MTC-4 Cable Assemblies — This 2m or 4m cable
assembly is terminated with a DB44 female connector on one end and is unterminated
at the other end. The female end mates to the male DB44 connector on the scanner card.
•
Model 2000-MTCD-2 Cable Assembly — This 2m cable assembly is terminated with
a DB44 female connector on one end and a DB50 male connector at the other end. The
female end mates with the scanner card.

1-6 General Information

2
Card Connections
and Installation
Card Connec-
tions 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-20 and
installing the card in a Model 2000-20 Multimeter. This section is arranged 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.
Handling precautions
To maintain high impedance isolation between channels, take care when handling the scanner
card to avoid contamination from such foreign materials as body oils. Such contamination can
substantially lower leakage resistances and degrade card performance. To avoid possible
contamination, always grasp the scanner card by the side edges. Do not touch board surfaces,
components, or areas adjacent to electrical contacts.
Dirt buildup 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, thoroughly clean it as explained in Section 4.

Card Connections and Installation 2-3
Connections
This paragraph provides the information necessary to connect your external test circuitry to
the scanner card.
NOTE All connections must be connected to the card before it is installed in a multimeter.
Connection precautions
WARNING Connection information for the Model 2000-SCAN-20 is intended for
qualified service personnel. Do not attempt to connect the DUT or external
circuitry to a scanner card unless qualified to do so.
To prevent electric shock that could result in serious injury or death, adhere
to the following safety precautions:
• Before making or breaking connections to the scanner card, make sure
the DMM power is turned off and power is removed from all external
circuitry.
• Do not connect signals that will exceed the maximum specifications of
the scanner card.
If both the front panel terminals and the scanner card terminals are
connected at the same time, the maximum signal ratings of the front panel
terminals are reduced to the maximum signal ratings of the scanner card.
As described in the International Electrotechnical Commission (IEC)
Standard IEC 664, scanner cards are Installation Category I and must not
be connected to mains.
Section 2 Page 3 Thursday, August 7, 2003 11:58 AM