Keithley 2000-SCAN-20 Service and user manual

Model 2000-SCAN-20 Scanner Card

A GREATER MEASURE OF CONFIDENCE

Instruction Manual

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.

S

afety 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 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

ment is operated within its specifications and operating limits, and for ensuring that operators are adequately trained.

Operators

instrument. They must be protected from electric shock and contact with hazardous live circuits.

Maintenance personnel

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

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.

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,

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

is the individual or group responsible for the use and maintenance of equipment, for ensuring that the equip-

use the product for its intended function. They must be trained in electrical safety procedures and proper use of the

perform routine procedures on the product to keep it operating properly, for example, setting the line

are trained to work on live circuits, and perform safe installations and repairs of products. Only properly

A good safety practice is to expect that hazardous voltage is present in any unknown

no conductive part of the circuit may be exposed.

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

information very carefully before performing the indicated procedure.

The

CAUTION

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.

heading in a manual explains dangers that might result in personal injury or death. Always read the associated

heading in a manual explains hazards that could damage the instrument. Such damage may invalidate the

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

General

Information

General

1

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.

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

injury or death. Always read the associated information very carefully before performing the
indicated procedure.

heading used in this manual explains dangers that might result in personal

General Information 1-3

The

CAUTION

card. Such damage may invalidate the warranty.

heading used in this manual explains hazards that could damage the scanner

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.

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

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 —

a DB44 female connector on one end and a DB50 male connector at the other end. The
female end mates with the scanner card.

General Information 1-5

— This 2m or 4m cable

This 2m cable assembly is terminated with

1-6 General Information

Card Connec-

tions and

Installation

2

Card Connections

and Installation

2-2 Card Connections and Installation

Introduction

WARNING

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.

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.

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.

Connections

This paragraph provides the information necessary to connect your external test circuitry to

the scanner card.

Card Connections and Installation 2-3

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.

2-4 Card Connections and Installation

Card configuration

Figure 2-1 shows a simplified schematic diagram of the Model 2000-SCAN-20. The scanner

card has 20 input channels and two outputs. Channels 1 through 20 are all switched by relays.

In 2-pole mode, the OUT A HI and LO connections are for all 20 channels. In 4-pole mode,
the OUT A HI and LO connections are for channels 1 through 10 and the OUT B HI and LO
connections are for channels 11 through 20.

4-pole paired channels are as follows:

• Channels 1 and 11

• Channels 2 and 12

• Channels 3 and 13

• Channels 4 and 14

• Channels 5 and 15

• Channels 6 and 16

• Channels 7 and 17

• Channels 8 and 18

• Channels 9 and 19

• Channels 10 and 20

Figure 2-1

Model 2000-SCAN-20 simplified schematic

User-installed
current shunt

Channel 1

Channel 2-9

Channel 10

User-installed
current shunt

Channel 11

Channel 12-19

Channel 20

HI

LO

HI

LO

HI

LO

HI

LO

HI

LO

HI

LO

2-Pole4-Pole

OUT A

(To DMM input jacks)

OUT B

(To DMM sense jacks)

Card connectors

Figure 2-2 shows the input and output connectors for the card. Card connector J1036 provides

the HI and LO input connections for all 20 channels, and J1035 provides the HI and LO outputs.
Terminal identification for connectors J1035 and J1036 is provided in Figure 2-3 and Table 2-1
and Table 2-2, respectively

The J1035 connects to a plug that has four separate test leads. These test leads connect to the
rear HI and LO INPUT and SENSE jacks on the multimeter. Refer to“Output connections to

multimeter” on page 2-16 for more information.

Card Connections and Installation 2-5

NOTE

The J1036 connects to a DB44 mass-terminated connector.

Figure 2-2

Card connectors

It is not necessary to connect the OUT B leads for 2-pole mode operation.

Red

Output

Connector

J1035

HI

LO

Black

To DMM
Sense

Red

Input

Connector

J1036

HI

LO

Black

To DMM
Input

2-6 Card Connections and Installation

Figure 2-3

Input and output connector terminal identification

Channel 1

Channel 2

Channel 3

Channel 4

Channel 5

Channel 6

Channel 7

Channel 8

Channel 9

Channel 10

Channel 11

Channel 12

Channel 13

Channel 14

Channel 15

Channel 16

Channel 17

Channel 18

Channel 19

Channel 20

26 HI

11 LO

29 HI

14 LO

33 HI

34 LO

23 HI

8 LO

39 HI

40 LO

43 HI

44 LO

20 HI

5 LO

37 HI

38 LO

27 HI

12 LO

30 HI

15 LO

2 HI

1 LO

21 HI

6 LO

24 HI

9 LO

41 HI

42 LO

18 HI

3 LO

35 HI

36 LO

25 HI

10 LO

28 HI

13 LO

19 HI

4 LO

22 HI

7 LO

4-Pole

2-Pole

1

16

31

HI 2

OUT A (To DMM Input Jacks)

LO 1
HI 4

OUT B (To DMM Sense Jacks)

LO 3

NOTE: The HI and LO input channel

pin designations correspond to
connector J1036.

The HI and LO output
pin designations correspond
to connector J1035.

J1036

J1035

12

15

30

44

34

Card Connections and Installation 2-7

Table 2-1

Output connector J1035 pin designations

Terminal Pin Designator Terminal Pin Designator

Output A, LO 1 Output B, LO 3

Output A, HI 2 Output B, HI 4

Table 2-2

Input connector J1036 pin designations

Mux Terminal Pin Designator Mux Terminal Pin Designator

Channel 1, HI 26 Channel 11, HI 2

Channel 1, LO 11 Channel 11, LO 1

Channel 2, HI 29 Channel 12, HI 21

Channel 2, LO 14 Channel 12, LO 6

Channel 3, HI 33 Channel 13, HI 24

Channel 3, LO 34 Channel 13, LO 9

Channel 4, HI 23 Channel 14, HI 41

Channel 4, LO 8 Channel 14, LO 42

Channel 5, HI 39 Channel 15, HI 18

Channel 5, LO 40 Channel 15, LO 3

Channel 6, HI 43 Channel 16, HI 35

Channel 6, LO 44 Channel 16, LO 36

Channel 7, HI 20 Channel 17, HI 25

Channel 7, LO 5 Channel 17, LO 10

Channel 8, HI 37 Channel 18, HI 28

Channel 8, LO 38 Channel 18, LO 13

Channel 9, HI 27 Channel 19, HI 19

Channel 9, LO 12 Channel 19, LO 4

Channel 10, HI 30 Channel 20, HI 22

Channel 10, LO 15 Channel 20, LO 7

NC 16 NC 31

NC 17 NC 32

2-8 Card Connections and Installation

Typical connecting schemes

The following paragraphs discuss typical connections for the scanner card.

Voltage connections

Figure 2-4 shows typical connections for voltage measurements. Note that all channels are

used in the 2-pole mode and that up to 20 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 through 20) can be used with this configuration.

Figure 2-4

Connections for voltage scanning

J1036

HI

CH 1

LO

HI

CH 20

LO

J1035

HI

OUT A

LO

HI

OUT B

LO

2000-SCAN-20 Card

HI

LO

HI

V

LO

Voltages

Under Test

HI

V

LO

To DMM

Input

Resistance connections

2-Pole connections

Figure 2-5 shows typical 2-pole resistor test connections. The 2-pole resistance configuration

can be used to test up to 20 DUTs.

Figure 2-5

Typical connections for 2-wire resistance scanning

J1036

HI

CH 1

LO

HI

CH 20

LO

Card Connections and Installation 2-9

Resistors

Under Test

J1035

HI

OUT A

LO

HI

OUT B

LO

2000-SCAN-20 Card

HI

LO

To DMM

Input

2-10 Card Connections and Installation

4-Pole connections

Typical 4-pole resistance connections are shown in Figure 2-6. This general configuration can
be used with all channels to scan 4-wire resistance measurements.

Figure 2-6

Typical connections for 4-wire resistance scanning

J1036

HI

CH 1

LO

HI

CH 2

LO

HI

CH 10

LO

HI

CH 11

LO

HI

CH 12

LO

Resistors

Under Test

HI

CH 20

LO

J1035

HI

OUT A

LO

HI

OUT B

LO

2000-SCAN-20 Card

HI

LO

HI

LO

To DMM Input

To DMM Sense

Current measurements

Current shunts can be installed on the circuit board to measure indirect AC and DC currents
through channels 1 and 11 only. The following paragraphs discuss installing current shunts and
the basic methods used to determine currents.

Card Connections and Installation 2-11

CAUTION

Current shunt locations

Figure 2-7 shows the locations for the user-installable current shunts. Location R103 is for

channel 11, and location R104 is for channel 1.

Figure 2-7

Current shunt locations

R103 (Channel 11 Shunt)

Board-mounted current shunt resistors can be installed only for channels 1
and 11. A channel that has been modified with a current shunt resistor
should not be used for voltage or resistance measurements.

R104 (Channel 1 Shunt)

Recommended current shunt values

Hole spacing on the circuit board is intended for 1/10W resistors. The resistance value will
depend on the current you intend to measure; 1k
cations. A 1k
power rating of the resistor.

For larger currents, decrease the shunt value. Conversely, the shunt value can be increased for
smaller currents.

CAUTION

Ω

resistor will allow you to switch currents up to 10mA without exceeding the

Do not exceed the maximum card signal levels:

• DC signals: 60V DC, 0.5A switched, 30VA maximum.

• AC signals: 30V AC, 0.5A switched, 15VA maximum.

Ω

resistors should be optimum for many appli-

2-12 Card Connections and Installation

Board soldering and cleaning precautions

NOTE

spread flux to other areas of the circuit board. Use solder with an OA (organic activated) flux.
Thoroughly clean the circuit board with pure water after soldering to remove all contaminants.
After cleaning with water, swab the area with pure methanol and allow the board to dry for
several hours in a 50°C environment before use.

Failure to observe the following precautions may result in degraded card
performance.

When soldering resistors, only touch areas associated with resistor installation and do not

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:

I = V/R

Where: I = current being determined

V= voltage measured by multimeter
R= shunt resistance value

Instead of manually calculating current, set up a Model 2000-20 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 manual for details on using math functions.

Card Connections and Installation 2-13

Current connections

Figure 2-8 shows typical connections for measuring currents using the

Model 2000-SCAN-20 with current shunts installed. As noted previously, only channels 1 and
11 have current shunts installed. This configuration can be used to scan the following:

• DC current

• AC current

Figure 2-8

Current connections

J1036

HI

CH 1

LO
HI

CH 2

LO

HI

CH 10

LO
HI

CH 11

LO
HI

CH 12

LO

HI

CH 20

LO

J1035

HI

OUT A

LO

HI

OUT B

LO

2000-SCAN-20 Card

AC or DC

A

Current

AC or DC

A

Current

NOTE: Current shunts

HI

To DMM Input

LO

must be installed
for channels 1
and 11.

2-14 Card Connections and Installation

Card installation and removal

This paragraph explains how to install and remove the Model 2000-SCAN-20 card assembly

from the Model 2000-20 Multimeter.

WARNING

NOTE To prevent contamination to the scanner card that could degrade performance,

Installation or removal of the Model 2000-SCAN-20 should be performed
only by qualified service personnel. Failure to recognize and observe
standard safety precautions could result in personal injury or death.

handle the card assembly only by the card edges.

Scanner card installation

Perform the following steps and refer to Figure 2-9 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 the external circuitry is discharged.

1. Pry out the two fasteners holding the OPTION SLOT cover plate to the rear panel of the
multimeter. Remove the cover plate.

2. Slide the card edges, component side up, into the guide rails inside the multimeter.

3. 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.

4. After installation, connect the output leads to the multimeter as discussed in the
following paragraph.

Figure 2-9

Card installation

Card Connections and Installation 2-15

Unlock Card

NOTE: Card connections

are removed
for clarity.

Ejector Arms (2)

Lock Card

2-16 Card Connections and Installation

Output connections to multimeter

After installation, connect the scanner card output leads to the multimeter rear panel jacks as

follows:

WARNING Signals applied to the front inputs of the multimeter cannot exceed the

ratings of the scanner card as long as the scanner card output leads are
connected to the multimeter rear panel input jacks.

For 2-pole operation, connect OUT A HI (red) to INPUT HI and connect OUT A LO (black)

to INPUT LO. See Figure 2-10.

NOTE Be sure to select the rear inputs with the multimeter front panel INPUTS switch when

using the scanner.

Figure 2-10

2-pole output connections

Input HI

Input LO

Out A

LO (Black)

Out A

HI (Red)

Card Connections and Installation 2-17

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 2-11.

NOTE Be sure to select the rear inputs with the multimeter front panel INPUTS switch when

using the scanner.

Figure 2-11

4-pole output connections

Out B

LO (Black)

Out B

HI (Red)

Sense LO

Scanner card removal

Perform the following steps to remove the scanner card from 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 the external circuitry is discharged.

Sense HI

Input LO

Out A

LO (Black)

Input HI

Out A

HI (Red)

1. Unlock the card by pulling the ejector arms outward.

2. Carefully slide the card out of the multimeter.

3. Install the cover plate over the OPTION SLOT and secure with the two fasteners if the
multimeter is to be operated without the scanner card installed.

2-18 Card Connections and Installation

Operation

3

Operation

3-2 Operation

Introduction

This section contains detailed information on front panel and IEEE-488 bus operation of the

Model 2000-SCAN-20. The information in this section is organized as follows:

• Signal limitations — Summarizes the maximum signals that can be applied to the

• Scanner card detection — Discusses how the multimeter detects a scanner card and

• Model 2000 multimeter front panel scanner controls and SCPI bus scanner

• SCPI scanner commands — Summarizes the bus commands necessary to control the

• Typical applications — Discusses typical applications for the Model 2000-SCAN-20.

• Measurement considerations — Discusses a number of measurement considerations to

Model 2000-SCAN-20.

how to use a bus command to determine whether or not a card is installed in the
multimeter and identify the type of card.

commands — Gives an overview of the Model 2000-20 Multimeter front panel controls
and corresponding IEEE-488 bus commands used to control the scanner card.

scanner card using the Model 2000-20 Multimeter.

take into account when using the scanner.

NOTE Before using the Model 2000-SCAN-20 scanner card, you should be thoroughly

familiar with the operation of the multimeter. See the multimeter manual for details.

Signal limitations

CAUTION To prevent damage to the Model 2000-SCAN-20, do not exceed the

Relay input signal limitations

Channels 1 through 20 are all relay inputs. To prevent overheating or damage to the relays,

never exceed the following maximum signal levels for these channels:

DC signals: 60V DC, 0.5A switched, 30VA (resistive load).

AC signals: 30V rms or 42.4V AC peak, 0.5A switched, 15VA (resistive load).

NOTE Model 2000-SCAN-20 is limited to non-hazardous voltages only.

maximum signal level specifications of the card.

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 multimeter will not recognize the presence of the card.

CAUTION Plugging in the scanner card with power turned on may result in damage to

both the Model 2000-SCAN-20 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 that determines whether or not a scanner card is
installed. Also, the Model 2000-20 multimeter can distinguish between a Model-2000-SCAN
10-channel card and the Model-2000-SCAN-20 20-channel card. The response to this query is
as follows:

Operation 3-3

• 0: Scanner not installed.

• 0,10CH: Model 2000-SCAN 10-channel card installed.

• 0,20CH: Model 2000-SCAN-20 20-channel card installed.

Refer to the multimeter manual for more details on using the *OPT? query.

3-4 Operation

Model 2000-20 multimeter front panel scanner controls and SCPI scanner commands

The following paragraphs give an overview of the various Model 2000-20 Multimeter front
panel controls and corresponding IEEE-488 SCPI bus commands used with the
Model 2000-SCAN-20.

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 , , ▲, and ▼ keys to select the channel you wish to close and press
ENTER.

If the channel number is between 1 and 10, the closed channel will display on the front
panel along with the 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.

NOTE For channels 11 through 20, more than one channel annuciator is lit. For example,

CH1 and CH10 are lit for channel 11, and CH1, CH9, and CH10 are lit for channel

20.

3. The and keys alone will also close the channels. Press the and keys until
the channel annunciator you want to close appears on the display.

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 channels. 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 Closing channel 21 selects the 4-pole operating mode.

Opening channels

Front panel

Use the front panel OPEN key to open all the card channels.

Remote interface

Use the :ROUTe:OPEN:ALL command to open all 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

want to open channels 1, 3, and 5, use the following command:

PRINT #1, "output 16; :route:multiple:open (@ 1,3,5)"

NOTE Opening channel 21 selects the 2-pole operating mode.

Selecting measurement function

Use the following procedure to select a specific measurement function for an internal

channel:

Operation 3-5

1. Use the and keys to select the desired channel.

2. Select the desired measurement function with the keys on the front panel. The various
measurement functions available are:

DCV: DC volts PERIOD: period
ACV: AC volts TEMP: simulated temperature

Ω2W: 2-wire ohms CONT: continuity
Ω4W: 4-wire ohms : diode test

(channels 1 through 10)

FREQ: frequency

3-6 Operation

Configuring scan parameters

This paragraph 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 and then CONFIG. The instrument will display the following prompt for
internal scanning:

TYPE: I20

Use the ▲ or ▼ key if EXT is displayed and press ENTER.

2. The following message will display:

MIN CHAN: 01

Use the ▲ and ▼ keys to select the channel at which the scanning will begin and press
ENTER.

3. The unit will display the following message:

MAX CHAN: 20

Use the , , ▲, and ▼ keys to select the channel at which the scanning will stop
and press ENTER.

4. The instrument will display the following message:

TIMER? OFF

Use the or key to select the ON option if desired and press ENTER. Select the
scan time when prompted and press ENTER:

00H:00M:01.000S

5. The unit will display the following message:

RDG CNT: 0020

Use the , , ▲, and ▼ keys to select the desired number of readings from the
selected list to be taken and stored by the instrument and press ENTER.

The instrument will store in memory the number of readings specified with RDG CNT.
After the scanning has been completed, you can access these readings by pressing the
RECALL key on the front panel and using the , , ▲, and ▼ keys to scroll through
the stored readings.

Operation 3-7

6. The following options start the scanning process:

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 scanning, 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 20 inclusively, use the following command:

PRINT #1, "output 16; :route:scan[:internal] (@1:20)"

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 manual.

Table 3-1

Summary of SCPI scanner commands

Command Description

:ROUTe

:CLOSE <list>

:STATe?

:OPEN ALL

:ALL

:MULTiple

:CLOSE <list>

:STATe?

:OPEN <list>

:SCAN

[:INTernal] <scan list>
:EXTernal <scan list>
:LSELect NONE | INTernal | EXTernal

[:SENSe[1]]

:FUNCTion <function list>

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. Uppercase 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.

Route subsystem.
Close channels.
Return all closed channels.
Open channels.
Open any closed channels.
Multiple channel commands:
Close specified channels (1 through 20).
Query closed channels.
Open specified channels.
Scanning commands.
Program internal scan list.
Program external scan list.
Select scan list.

Sense subsystem.
Select measurement function.

Typical applications

Resistor testing

The Model 2000-SCAN-20 can be used to test up to 20 resistors using 2-wire measurements
or up to ten resistors using 4-wire measurements. Such tests use the Model 2000-20 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-20 card provides the switching function, while the Model 2000-20
Multimeter makes the resistance measurements. Since only 2-pole switching is required for this
application, one Model 2000-SCAN-20 card can be used to switch up to 20 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
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

Operation 3-9

HI

LO

DMM 2000-20

Rear Panel

2000-20

Multimeter

2000-SCAN-20

Out A

A. Test Configuration

1

20

Ω

2000-SCAN-20

B. Simplified Equivalent Circuit

1

20

DUTs
(20)

R

DUT

3-10 Operation

4-wire resistance tests

More precise measurements over a wider range of system and DUT conditions can be
obtained using the 4-wire measurement scheme shown in Figure 3-2. Here, separate sense leads
from the Model 2000-20 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 ten resistors can be
tested using this configuration.

Figure 3-2

4-wire resistance test connections

2000-SCAN-20

Out A

DMM 2000-20

Rear Panel

HI

LO

Sense HI

Sense LO

Out B

A. Test Configuration

HI

Sense HI

LO

Ω

Sense LO

2000-20

B. Simplified Equivalent Circuit

2000-SCAN-20

DUT

1

DUTs

(10)

10

R

1
10

11
20

Current measurements

Although the Model 2000-SCAN-20 is not intended for direct current measurements, on-card
shunt resistors can be installed for channels 1 and 11 to allow for indirect current measurements.

Figure 3-3 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 3-3

Connections for current measurements

Out A

HI

LO

DMM 2000-20

Rear Panel

A. Test Configuration

2000-SCAN-20

CH 1

CH 11

Operation 3-11

User-installed

Shunts

A

A

DUTs (2)

User-installed

Shunt

V

2000-20

2000-SCAN-20

B. Simplified Equivalent Circuit

A

DUT

The current through each shunt resistor can be calculated as follows:

I = V/R

Where: I = current being determined

V = voltage measured by multimeter
R = shunt resistance value

Instead of manually calculating current, set up a Model 2000-20 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 manual for details on using math functions.

3-12 Operation

Measurement considerations

Many measurements made with the Model 2000-SCAN-20 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

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.

Figure 3-4

Path isolation resistance

RDUT

RPATHVRIN

EDUT

DUT Scanner

= Source Resistance of DUT

RDUT

= Source EMF of DUT

EDUT

= Path Isolation Resistance

RPATH

= Input Resistance of Multimeter

RIN

Path isolation resistance forms a signal path that is in parallel with the equivalent resistance
of the DUT, as shown in Figure 3-4. 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 3-5. Also, leakage currents can be generated
through these resistances by voltage sources in the system.

Card

DMM

Figure 3-5

Voltage attenuation by path isolation resistance

RDUT

Operation 3-13

EDUT RPATH

EOUT

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.

EOUT

+

RPATH
RPATH

EDUT

=

RDUT

Electromagnetic interference (EMI)

The electromagnetic interference characteristics of the Model 2000-20 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 handheld radios.

• Devices incorporating microprocessors and high-speed digital circuits.

• Impulse sources as in the case of arcing in high-voltage environments.

3-14 Operation

Ground loops

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.

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 inFigure 3-6, 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 3-6

Power line ground loops

Signal Leads

Instrument 1 Instrument 2 Instrument 3

Ground Loop

Current

Power Line Ground

Figure 3-7 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
instruments in the test setup may not be designed in this manner. When in doubt, consult the
manual for all instrumentation in the test setup.

Figure 3-7

Eliminating ground loops

Instrument 1 Instrument 2 Instrument 3

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, only use the scanner card
in clean, dry environments to avoid contamination.

Operation 3-15

Power Line Ground

If the connector insulators should become contaminated, either by inadvertent touching or
from air-borne deposits, clean them with a cotton swab dipped in clean methanol. After thor­oughly cleaning, allow the insulators to dry for several hours in a low-humidity environment
before use, or you can dry them more quickly using dry nitrogen.

3-16 Operation

Service

Information

4

Service

Information

4-2 Service Information

WARNING The information in this section is intended only for qualified service

Introduction

This section contains information necessary to service the Model 2000-SCAN-20 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.

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.

Handling and cleaning precautions

Because of the high-impedance areas on the Model 2000-SCAN-20, take care 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 side edges.

• 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 remove the flux.

• Once the flux has been removed, swab only the repaired area with methanol and then
blow dry the board with dry nitrogen gas.

• After cleaning, allow the card to dry in a 50°C low-humidity environment for several
hours before use.

Performance verification

The following paragraphs discuss performance verification procedures for the Model 2000-

SCAN-20, 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. Do not touch connector insulators, board
surfaces, or components.

Service Information 4-3

Failure of any performance verification test may indicate that the scanner card is con­taminated. See “Handling and cleaning precautions” in this section for information
on cleaning the card.

Environmental conditions

Make all verification measurements at an ambient temperature between 18° and 28°C and at

a relative humidity of less than 70%.

4-4 Service Information

Recommended equipment

Table 4-1 summarizes the equipment necessary for performance verification and the

application for each item.

Table 4-1

Recommended verification equipment

Description Model/part Specifications Application

Multimeter

Electrometer with voltage

source

Sensitive Digital Voltmeter

Triax cable (unterminated)

Low-thermal cable

#22AWG solid copper wire

#22AWG Teflon-insulated

stranded wire

Triax adapter (3-slot male to

2-lug female)

Path resistance tests

Perform the following steps to verify that the path resistance of each channel is within the

specified values.

Keithley 2000-20

Keithley 6517A

Keithley 182

Keithley 7025

Keithley 1484

—

—

Keithley 6171

100Ω; 100ppm of
reading; 40ppm of
range

20pA, 200pA; 1.0%
100V source; 0.15%

3mV; 60ppm

—

—

—

—

—

Control card, measure path resistance

Path isolation

Contact potential

Path isolation

Contact potential

Path resistance

Path isolation

Path isolation

NOTE To perform this test, you must custom-wire a cable to connect to the scanner card

connections.

1. Connect the HI and LO inputs of all 20 channels together to make one common input
using #22AWG solid copper jumper wires (Figure 4-1).

NOTE Make sure all jumper wires are clean and free of oxides.

2. Connect the output cables to OUT A HI and LO as shown in Figure 4-1.

3. With the power off, install the scanner card in a Model 2000-20 Multimeter.

Service Information 4-5

4. Turn on the multimeter and allow it to warm up for one hour before proceeding.

5. Select the Ω2W function and the 100Ω range on the multimeter.

6. Temporarily connect a second set of output leads, identical in length and type to the leads
connected to the scanner card output, to the multimeter rear panel HI and LO INPUT
jacks. Be sure to select the rear panel terminals with the front panel INPUT switch.

7. Short the free ends of the temporary leads together and allow the reading to settle. Enable
the multimeter REL mode after settling, and leave REL enabled for the remainder of the
path resistance tests.

8. 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 (Figure 4-1).

9. Program the multimeter to close channel 1.

10. Note the resistance reading on the multimeter. Verify that the reading is <2Ω.

11. Repeat steps 9 and 10 for channels 2 through 20. Verify that the path resistance for each
channel is <2Ω.

12. After completing the tests, turn off the multimeter 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.)

Figure 4-1

Connections for path resistance checks

Jumper HI and LO
of all 20 Channels

Channel 1

Channel 2-9

Channel 10

HI
LO

HI

LO

4-Pole

2-Pole

HI

LO

HI

LO

OUT A

OUT B

Input

HI

DMM 2000-20

Rear Panel

Input

LO

Channel 11

Channel 12-19

Channel 20

HI
LO

HI

LO

Model 2000-SCAN-20

4-6 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.

NOTE To perform this test, you must custom-wire a cable to connect to the scanner card

1. Connect 1 in. #22AWG bare copper jumper wires between the HI and LO inputs of each
channel (Figure 4-2).

2. Connect the Model 182 Sensitive Digital Voltmeter to OUT A HI and LO using the low­thermal cable (Figure 4-2).

3. With the power off, install the scanner card in the Model 2000-20 Multimeter.

4. Turn on the multimeter and the voltmeter. Allow the voltmeter to warm up for two hours
before taking measurements.

5. Select the 3mV range on the voltmeter.

6. Select the DCV function on the multimeter.

7. Program the multimeter to close channel 1.

8. Verify that the voltmeter reading is <2µV.

9. Repeat steps 7 and 8 for all 20 channels.

10. After completing all measurements, turn off the multimeter power, remove the scanner
card, and disconnect all jumpers and test leads.

connections.

Figure 4-2

Connections for contact potential tests

Connect bare copper jumpers between
HI and LO of each channel

Channel 1

Channel 2-9

Channel 10

Channel 11

Channel 12-19

Channel 20

HI
LO

HI
LO

4-Pole

HI
LO

HI
LO

Model 2000-SCAN-20

2-Pole

KEITHLEY

182 SENSITIVE DIGITAL VOLTMETER

HI

LO

HI
LO

Model 182

OUT A

OUT B

TRG
SRQ
REM
TALK
LSTN

Model 1484
Low-Thermal Cable
(Unterminated)

Isolation tests

These tests check the leakage resistance (isolation) between all HI and LO inputs for each
channel and from the HI and LO inputs to chassis ground. In general, the test is performed by
applying a voltage (60V) across the connections and then measuring the leakage current. The
isolation resistance is then calculated as R = V/I. In the following procedure, the Model 6517A
Electrometer functions as a voltage source and as an ammeter. In the R function, the
electrometer internally calculates the resistance from the known voltage and current levels and
displays the resistance value.

Perform the following steps to check isolation:

NOTE To perform this test, you must custom-wire a cable to connect to the scanner card

1. Turn off the Model 2000-20 Multimeter if it is on and remove the scanner card.

2. Remove any jumpers or test leads connected to the card.

3. Turn on the Model 6517A Electrometer and allow the unit to warm up for two hours
before testing.

4. Connect a 4 in. length of Teflon-insulated #22AWG stranded wire to every HI and LO
input and output on the scanner card (connectors J1035 and J1036). Mark the free end
of each wire so you can identify the wires when the scanner card is installed.

5. With the power off, install the scanner card in the multimeter.

6. Connect the electrometer to OUT A HI and LO of the scanner card as shown in

Figure 4-3.

Service Information 4-7

connections.

Figure 4-3

Connections for same-channel isolation tests

Source V and

Com

(Ground Link

Removed)

Model 6171
Triax Adapter

Model 7025

Unterminated

Triax Cable

Banana to

Banana

Cable

Model 6517A

Measure V/I

V-Source LO

V-Source HI

HI

(Red)

Unterminated to

Banana Cable

Channel 1

Channel 2-9

Channel 10

Channel 11

Channel 12-19

Channel 20

Model 2000-SCAN-20

HI
LO

HI
LO

HI
LO

HI
LO

4-Pole

2-Pole

HI
LO

HI
LO

OUT A

OUT B

4-8 Service Information

WARNING The following steps use a 60V. Be sure to remove power from the circuit

before making connection changes.

7. Place the electrometer in the R measurement function.

8. Turn on the multimeter power.

9. Program the multimeter to close channel 1.

10. On the electrometer, source 60V.

11. After allowing the reading on the electrometer to settle, verify that the reading is
>100MΩ (10

8

Ω). This measurement represents the isolation resistance between channel

1 HI and LO.

12. Turn off the electrometer voltage source.

13. Repeat steps 9 through 12 for channels 2 through 20. Be sure the channel under test is
closed.

14. Turn off the multimeter power.

15. With the Model 6517A Electrometer voltage source off, connect the electrometer to
channel 1 HI and channel 2 HI as shown in Figure 4-4.

Figure 4-4

Connections for channel-to-channel isolation tests

Com

(Ground Link

Removed)

Model 6171
Triax Adapter

Unterminated

Banana to

Banana

Cable

Model 7025

Triax Cable

Source V and
Measure V/I

V-Source LO

V-Source HI

Model 6517A

Unterminated to

Banana Cable

HI

(Red)

Channel 1
Channel 2-9

Channel 10

Channel 11

Channel 12-19

Channel 20

Model 2000-SCAN-20

HI
LO

HI
LO

4-Pole

HI
LO

HI
LO

16. Turn on the Model 2000-20 Multimeter power.

17. Program the multimeter to close channel 1.

18. On the electrometer, source 60V.

19. After allowing the reading on the electrometer to settle, verify that the reading is
>100MΩ (10

8

Ω). This measurement represents the isolation resistance between channel

1 HI and channel 2 HI.

20. Turn off the electrometer voltage source.

2-Pole

HI
LO

HI
LO

OUT A

OUT B

21. Repeat steps 14 through 20 to measure isolation resistance between channel 1 HI and
each HI input of channels 3 through 20. Be sure the electrometer is connected to the HI
inputs of the two channels being tested and channel 1 is closed.

22. Repeat steps 14 through 21 for the LO inputs of channels 1 through 20. Be sure the
electrometer is connected to the LO inputs of the two channels being tested and channel
1 is closed.

23. Turn off the multimeter power.

24. With the electrometer voltage source off, connect the Model 6517A Electrometer to
channel 1 HI and chassis ground as shown in Figure 4-5.

Figure 4-5

Connections for HI and LO input-to-chassis ground isolation tests

Model 7025

Unterminated

Triax Cable

HI

(Red)

Channel 1
Channel 2-9

Channel 10

Channel 11

Channel 12-19

Channel 20

Com

(Ground Link

Removed)

Model 6171
Triax Adapter

Chassis Ground

Banana to

Banana

Cable

Source V and
Measure V/I

V-Source LO

V-Source HI

Model
6517A

Unterminated to

Banana Cable

Service Information 4-9

Model 2000-SCAN-20

HI
LO

HI
LO

4-Pole

HI
LO

HI
LO

2-Pole

HI
LO

HI
LO

OUT A

OUT B

25. Turn on the Model 2000-20 Multimeter power.

26. Program the multimeter to close channel 1.

27. On the electrometer, source 60V.

28. After allowing the reading on the electrometer to settle, verify that it is >100MΩ (10

8

Ω).

29. Turn off the electrometer voltage.

30. Turn off the multimeter power.

31. Repeat steps 24 through 30 for channels 2 through 20. One electrometer lead should be
connected to the HI input of the channel being testing, and the other lead should be con­nected to chassis ground.

32. Repeat steps 24 through 31 for the LO inputs of channels 1 through 20. One electrometer
lead should be connected to the LO input of the channel being tested, and the other lead
should be connected to chassis ground. Also, channel 1 should be closed.

4-10 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 To prevent damage, assume all parts are static-sensitive.

1. Such devices should be transported and handled only in containers specially designed to
prevent or dissipate static buildup. 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.

2. 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.

3. Handle the devices only by the body; do not touch the pins or terminals.

4. Any printed circuit board into which the device is to be inserted must first be grounded
to the bench or table.

5. Use only anti-static type de-soldering tools and grounded-tip soldering irons.

Principles of operation

The following paragraphs discuss the basic operating principles for the
Model 2000-SCAN-20 and can be used as an aid in troubleshooting the card. The schematic
drawing of the card is shown on drawing number 2000-186 located at the end of Section 5.

Block diagram

Figure 4-6 shows a simplified block diagram of the Model 2000-SCAN-20. Key elements

include the relay drivers, relays, and power-up reset circuit. These various elements are
discussed in the following paragraphs.

Figure 4-6

Block diagram

Service Information 4-11

To

Multimeter

Relay control

Card relays are controlled by serial data transmitted via the relay DATA line. A total of six
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 six 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.

Clock

Data

Strobe

+5V

Relay

Drivers

U102-U107

Power-on

Reset

U101

Enable

Relays

K101-K121

User Connections

Switching circuits

Relays K101 through K105 and K107 to K121 perform input switching, while K106
configures the card for 2-pole or 4-pole operation.

Power-on safeguard

A power-on safeguard circuit, made up of U101 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.

4-12 Service Information

Replace-

able Parts

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-20.

Parts list

A parts list for the scanner card is included in a table integrated with a 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-20)

• Card serial number

• Part description

• Circuit description, if applicable

• Keithley part number

Factory service

If the card is to be returned to Keithley Instruments for repair, perform the following:

• 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.

NOTE It is not necessary to return the Model 2000-20 Multimeter with the card.

Replaceable Parts 5-3

Component layout and schematic diagram

A component layout drawing and schematic diagram are included on the following pages

integrated with the parts list (Table 5-1) for the Model 2000-SCAN-20.

Table 5-1

Model 2000-SCAN-20 parts list

Circuit desig. Description

Keithley part
no.

C101
C102
C103-110

J1035
J1036

K101-121

P1034

R101
R102

U101
U102-107

4-40 Pem Nut
4-40 x 5/16 Phillips Pan Head Screw
Card Ejector
Crimp Housing
Crimp Terminal, Female
Latching Block
Sleeved Banana Plug Test Lead

CAP, 100µF, 20%, 16V, TANTALUM (7243)
CAP, 10µF, 20%, 25V, TANTALUM (D7243)
CAP, .1µF, 20%, 50V, CERAMIC (1206)

CONN, RT ANGLE HEADER
CONN, RT ANGLE

RELAY, MINIATURE (DPDT) TQ2E-L2-5V

CONN, FEMALE DUAL 16-PIN

RES, 4.75K, 1%, 100MW, THICK FILM (0805)
RES, 1K, 1%, 100MW, THICK FILM (0805)

IC, SUPPLY VOLT SUPERVISOR, TL7705A (SOIC)
IC, 8 STG/SHFT/STR REG, UCN5841LW (SOLIC)

FA-131
4-40x5/16PPH
FA-237
CS-1018-1
CS-1019-1
FA-304
CA-109A

C-504-100
C-440-10
C-418-.1

CS-1017-1
CS-967-2

RL-155

CS-455

R-418-4.75K
R-418-1K

IC-860
IC-857

5-4 Replaceable Parts

A

Specifications

A-2 Specs and Accessories

GENERAL:

20 Channels:

20 channels of 2-pole relay input. All channels

configurable to 4-pole.

Relay Type: Latching electromechanical.
Actuation Time: <3.5ms.
Safety: Conforms with European Union Directive 73/23/EEC.
EMC: Conforms with European Union Directive 89/336/EEC.

CAPABILITIES: Multiplex one of twenty 2-pole or one of ten

4-pole signals into DMM.

INPUTS

Scanner Configuration

Channel 1

Channel 2–9

Channel 10

HI

LO

HI

LO

Maximum Signal Level:

DC Signals: 60V DC CAT I, 0.5A switched, 30VA maximum

(resistive load).

AC Signals: 30V AC rms CAT I or 42.4V AC peak, 100kHz maxi-

mum, 0.5A switched, 15VA maximum (resistive load).

Contact Life: >105operations at maximum signal level; >10

operations cold switching.

Contact Resistance: <1Ω at end of contact life.
Contact Potential:

<±1µV typical per contact, 2µV max. <±1µV typical per con­tact pair, 2µV max.

Connector Type: 44 pin male D-subminiature.
Isolation Between Any Two Terminals: >108Ω, <75pF.

8

Channel 11

Channel 12–19

Channel 20

HI

LO

HI

LO

Isolation Between Any Terminal and Earth: >108Ω, <150pF.
Common Mode Voltage: 42.4VAC peak; 60VDC between any

terminal and earth.

Maximum Voltage Between Any Two Terminals: 42.4VAC peak, 60VDC.
Maximum Voltage Between Any Terminal and Model 2000 Input LO: 42.4VAC peak, 60VDC.

Internal Scanner Speed

MAXIMUM INTERNAL SCANNER RATES

RANGE: Channels/s

TRIGGER DELAY = 0

DCV

All : 100 All : 90 All : 95 <10MΩ : 31 All : 60

TRIGGER DELAY = AUTO

DCV

0.1 V : 95 All : 1.8 100 Ω : 81 100 Ω : 28 All : 60
1 V : 100 1 kΩ : 81 1 kΩ : 28

10 V : 101 10 kΩ : 42 10 kΩ : 21

100 V : 70 100 kΩ : 28 100 kΩ : 17

1000 V : 70 1 MΩ : 8 1 MΩ : 7

1

2

2

ACV

ACV

2,3

2,3

2 WIRE 4 WIRE
OHMS2OHMS2TEMPERATURE

2 WIRE 4 WIRE
OHMS2OHMS2TEMPERATURE

2

2

10 MΩ : 5 10 MΩ : 5

100 MΩ : 3 100 MΩ : 3

HI

OUT A

LO

HI

OUT B

LO

2-Pole4-Pole

Internal Scanner Speed Notes

1. Speeds are for 60Hz operation using factory default operating conditions (*RST). Auto Zero off, Auto Range off, Display off, sample count = 1024.

2. NPLC = 0.01.

3. DETector:BANDwidth 300.

ENVIRONMENTAL:

Operating Environment:
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 0.3kg (7 oz.).

Specifications are subject to change without notice.

Specified for 0°C to 50°C. Specified to 80% R.H. at 35°C.

Index

G

General Information 1-1

Numerics

2-pole output connections 2-16
2-wire resistance test connections 3-9
4-pole output connections 2-17
4-wire resistance test connections 3-10

B

Block diagram 4-11

C

Card Connections and Installation 2-1
Card connectors 2-5
Card installation 2-14, 2-15
Card installation and removal 2-14

Output connections to multimeter 2-16
Scanner card installation 2-14

Scanner card removal 2-17
Card removal 2-14
Component layout and schematic diagram 5-3
Connections 2-3

Card configuration 2-4

Card connectors 2-5

Connection precautions 2-3
Connections for channel-to-channel isolation

tests 4-8
Connections for contact potential tests 4-6
Connections for current measurements 3-11
Connections for HI and LO input-to-chassis

ground isolation tests 4-9
Connections for path resistance checks 4-5
Connections for same-channel isolation

tests 4-7
Connections for voltage scanning 2-8
Current connections 2-13
Current shunt locations 2-11

H

Handling and cleaning precautions 4-2

Handling precautions 4-2
Soldering precautions 4-3

Handling precautions 2-2

I

Input and output connector terminal

identification 2-6
Input connector J1036 pin designations 2-7
Introduction 1-2, 2-2, 3-2, 4-2, 5-2

M

Manual addenda 1-3
Measurement considerations 3-12

Electromagnetic interference (EMI) 3-13
Ground loops 3-14
Keeping connectors clean 3-15
Magnetic fields 3-13
Path isolation 3-12

Model 2000-20 multimeter front panel scanner

controls and SCPI scanner commands 3-4

Closing channels 3-4

Front panel 3-4
Remote interface 3-4

Configuring scan parameters 3-6

Front Panel 3-6
Remote interface 3-7

Opening channels 3-5

Front panel 3-5
Remote interface 3-5

Selecting measurement function 3-5
Model 2000-SCAN-20 parts list 5-3
Model 2000-SCAN-20 simplified

schematic 2-4

E

Eliminating ground loops 3-15

F

Factory service 5-2
Features 1-2

O

Operation 3-1
Optional accessories 1-5
Ordering information 5-2
Output connector J1035 pin designations 2-7
Output connector terminal identification 2-6

P

Parts list 5-2
Path isolation resistance 3-12
Performance verification 4-3

Contact potential tests 4-6
Environmental conditions 4-3
Isolation tests 4-7
Path resistance tests 4-4

Recommended equipment 4-4
Power line ground loops 3-14
Principles of operation 4-10

Block diagram 4-10

Power-on safeguard 4-11

Relay control 4-11

Switching circuits 4-11

R

Recommended verification equipment 4-4
Repacking for shipment 1-4
Replaceable Parts 5-1

S

Safety symbols and terms 1-3
Scanner card detection 3-3

Power-up detection 3-3

Scanner option bus query 3-3
SCPI scanner commands 3-8
Service Information 4-1
Signal limitations 3-2

Relay input signal limitations 3-2
Special handling of static-sensitive

devices 4-10

Specifications 1-3, A-1
Summary of SCPI scanner commands 3-8

T

Typical applications 3-9

Current measurements 3-11
Resistor testing 3-9

2-wire resistance tests 3-9
4-wire resistance tests 3-10

Typical connecting schemes 2-8

Current measurements 2-11, 2-12

Board soldering and cleaning

precautions 2-12
Current connections 2-13
Current shunt locations 2-11
Recommended current shunt

values 2-11

Resistance connections 2-9

2-Pole connections 2-9
4-Pole connections 2-10

Voltage connections 2-8

Typical connections for 2-wire resistance

scanning 2-9

Typical connections for 4-wire resistance

scanning 2-10

U

Unpacking and inspection 1-3

Handling precautions 1-4
Inspection for damage 1-3
Instruction manual 1-4
Shipment contents 1-4

V

Voltage attenuation by path isolation

resistance 3-13

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 ❑ Batteries and fuses are OK

❑ Front panel operational ❑ All ranges or functions are bad ❑ Checked all cables

Display or output (check one)

❑ Drifts ❑ Unable to zero ❑ Unstable

❑ Overload ❑ Will not read applied input

❑ Calibration only ❑ Certificate of calibration required ❑ Data required

(attach any additional sheets as necessary)

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.

Specifications are subject to change without notice.

All Keithley trademarks and trade names are the property of Keithley Instruments, Inc.
All other trademarks and trade names are the property of their respective companies.

Keithley Instruments, Inc. 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: [phone]

1-888-KEITHLEY (534-8453) • www.keithley.com

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© Copyright 2003 Keithley Instruments, Inc.

Printed in the U.S.A.

5/03