Keithley 7076 Service manual

Model

7076

General Purpose Matrix Card

Dual 4 x 12
Instruction Manual

Contains Operating and Servicing Information

Publication Date: April 1991
Document Number: 7076-901-01 Rev. B

WARRANTY

Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1 year from date of
shipment.

Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries,
diskettes, and documentation.

During the warranty period, we will, at our option, either repair or replace any product that prows to be defective

To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in Cleveland, Ohio. You will
be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service facility. Repairs
will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for the balance of the origi­nal warranty period, or at least 90 days.

LIMITATION OF WARRANTY

This warranty does not apply to defects resulting from product modification without Keithley’s express written consent, or misuse of
any product ot’ part. This warranty also does not apply to fuses, software. non-rechargeable batteries, damage from battery leakage, or
problems arising from normal wear or failure to follow instructions.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN ARE
BUYER’S SOLE AND EXCLUSIVE REMEDIES.

NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT, INDI­RECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRUMENTS AND
SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF
SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL
AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR DAMAGE TO PROPERTY.

Keithley Instruments, Inc. * 28775 Aurora Road * Cleveland, OH 44139 - 216-248-0400 -Fax: [phone] - http://www.keithley.com

General Purpose Matrix Card Dual 4

Model 7076

Instruction Manual

x

12

01990, Keithley Instruments, Inc.

All rights reserved.

Cleveland, Ohio, U. S. A.

Document Number: 7076-901-01

All Keithley product names are trademarks or registered trademarks of Keithky Instruments, Inc.
Other brand and product names are trademarks or registered trademarks of their respective holders

SAFETY PRECAUTIONS

The following safety precautions should be observed before using the Model 7076 and the associated instruments.

This matrix card is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety

precautions required to avoid possible injury. Read over this manual carefully before using the matrix card.

ALWAYS remove power from the entire system (Model 707, test instruments, DUT, etc.) and discharge any capacitors
before doing any of the following:

1. Installing or removing the matrix card from the mainframe.

2. Connecting or disconnecting cables from the matrix card. The pins of cable connectors are easily accessible making
them extremely hazardous to handle while power is applied.

3. Making internal changes to the card (such as removing or installing jumpers).

Exercise extreme caution when a shock hazard is present at the test f?xture. User-supplied lethal voltages may be present
on the tlxture or the connector jacks. The American National Standards Institute (ANSI) states that a shock hazard exists
when voltage levels greater than 30V RMS or42.4V peak are present. A good safety practice is to expect that hazardous
voltage is present in any unknown circuit before measuring.

Do not connect the card or any other instrumentation to humans.

Inspect the connecting cables and test leads for possible wear, cracks, or breaks before each use.

For maximum safety, do not touch the test fixture, test cables or any instruments while power is applied to the circuit
under test.

Do not touch any object which could provide a current path to the common side of the circuit under test or power line
(earth) ground.

Do not exceed the maximum signal levels of the test fixture, as defined in the specifications and operation section of this
manual.

Do not connect the matrix card directly to unlimited power circuits. This product is intended to be used with impedance
limited sources. NEVER connect the matrix card directly to ac mains.

When connecting sources, install protective devices to limit fault current and voltage to the card.

The chassis connections must only be used as shield connections for measuring circuits, NOT as safety earth ground

connections.

Model 7076 Dual 4x12 Two-Pole Matrix Card

MATRIXCON”GURATION:Dual4rowsby12columns.Alsocanfigurableas8rowsby

12 mhmns. Jumpers can be removed to isolate any row from the backplane.
CROSSPOINT CONFIGURATION: 2 pole Form A (HI, GUARD).
CONNECTOR TYPE: 25.pin subminiature D connector, two for column connection, one

far row connection.

MAXIMUM

DC Signals: IIOV DC, IA switched, 30VA ksistive load).

AC Signals: 175” AC peak, IA switched, 62SVA (resistive load).
COMMON MODE VOLTAGE: IIOV DC, 175V AC peak pin to pi” or pi” to chassi%
CONTACT LIFE:

Cold Switching: 10s closures.

At M.Mm”rn Signal Level: 105 closures.
PATH RESISTANCE (per conductorb <0.5On initial, <1.5R at end of contact life
CONTACTPOTENTIAL: <5pV per crosspaint (HI lo GUARD).
OFFSET CURRENT: <lOOpA.
ISOLATION:

PatlIz >lOw2, <7PF.

Differential: >lOQ l2opF nominal.

Common Mode: >lOQ 2OOpFnominal.
CROSSTALK (IMHr, Mfi 1o;db <-5OdB.
INSERTION LOSS (IMHz, 5On source, 5OR load): 0.05dB typical.
3dB BANDWIDTH (500 load): 15MHz typical.
RELAY DRIVE CURRENT (per crosspoint): 28mA.
RELAY SE’ITLING TIME: <3ms.
ENVIRONMENT:

Operating: 0’ to 5O”C, up to 35°C at 70% R.H.

storage: -250 to WC.
ACCESSORY SUPPLIED: instruction manual, jumpers for 8 x 12 expansion.

SIGNAL LEVEL:

5pcifications subject to change without notice.

Column

Jumpers

- (user

Table of Contents

SECTION 1 - General Information

1.1 INTRODUCTION

1.2

1.3 WARRANTY INFORMATION

1.4 MANUAL ADDENDA

1.5

1.6

1.7

1.7.1 Inspection for Damage

1.7.2 Shipping Contents

1.7.3 Instruction Manual

1.8

1.9 OPTIONAL ACCESSORIES

FEATURES .

SAFETY SYMBOLS AND TERMS
SPECIFICATIONS . .
UNPACKING AND INSPECTION

. . .

REPACKING FOR SHIPMENT

SECTION 2 - Operation

2.1

2.2

2.3

2.4 BASIC MATRIX CONFIGURATIONS

2.4.1 4x24Matrix

2.4.2

2.5

2.5.1

2.5.2

2.5.3

2.5.4

2.6

2.6.1 Standard Cable (Model 7075-MTC)

2.6.2 High Isolation Cables (Model 7076-RMTC and Model 707&CMTC)

2.7

2.7.1 Backplane Row Jumpers

2.7.2

2.7.3 Wide Matrix Expansion

2.7.4 Partial Matrix Implementation

2.7.5

2.8

2.8.1 Single Card System

2.8.2 Multiple Card System

2.8.3

2.8.4 Matrix/Multiplexer System

2.9

INTRODUCTION
HANDLING PRECAUTIONS
CARD INSTALLATION AND REMOVAL

8xl2Matrix .........................................

TYPICAL MATRIX SWITCHING SCHEMES

Single-ended Switching.
Differential Switching

Guarding ...........................................

Sensing .............................................

CONNECTIONS

MATRIXEXPANSION. ..................................

Narrow Matrix Expansion

Mainframe Matrix Expansion

T(PICAL CONNECTION SCHEMES

Multiple Mainframe System

BANDWIDTH and CROSSTALK

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1-l
l-1
1-l
1-l
1-l
1-l
1-l
1-l
l-2
l-2
l-2

l-2

2-l
2-l
2-l

2-2
2-6

2-7

2-8
2-8
2-8
2-9
2-9
2-10
2-11

2-13
2-15
2-15
2-17
2-18
2-19
2-19
2-20
2-20
2-21
2-21

2-22
2-25

SECTION 3

3.1

3.2 THICK FILM RESISTOR NETWORK TESTING

3.2.1 Four-terminal Ohms Measurements

- Applications

INTRODUCTION ..............................................................

..............................................

3-1

....................................... 3-l

3-3

3.2.2

VoltageDividerChecks

3.3 TRANSISTOR TESTING

3.3.1

3.3.2

Current Gain Checks
Is and Vm Measurements

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SECTION 4 - Service Information

3-4

. 3-6

3-6
3-8

4.1

4.2

4.3

4.4

4.4.1

4.4.2

4.4.3

4.4.4

4.4.5

4.4.6

4.4.7

4.4.8

4.5

4.5.1

4.5.2

4.5.3

4.6

4.7

4.7.1

4.7.2

INTRODUCTION
HANDLING AND CLEANING PRECAUTIONS

RELAY TEST PROGRAM SET-UP

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........

...................

PERFORMANCE VERIFICATION ...................

Environmental Conditions
Recommended Equipment
Matrix Card Connections

Path Resistance Tests
Offset Current Tests
Contact Potential Tests
Path Isolation Tests

.............................

Differential and Common Mode Isolation Tests

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........

IWNCIPLES OF OPERATION ......................

Card Identification
Switching Circuitry
Power Up Safeguard

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SPECIAL HANDLING OF STATIC-SENSITIVE DEVICES
TROUBLESHOOTING

Recommended Equipment
Troubleshooting Procedure

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4-l
4-l
4-l
4-2
4-2
4-3
4-3
4-3
4-4
4-6
4-7
4-9
4-12

. 4-12

4-12

4-12
4-13

4-13

. 4-13

4-13

SECTION 5

5.1

5.2

5.3

5.4

5.5

INTRODUCTION
PARTSLIST
ORDERING INFORMATION
FACTORYSERVICE
COMPONENT LAYOUT AND SCHEMATIC DIAGRAM

- Replaceable Parts

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5-l

5-l

5-l

5-l

5-l

SECTION 2 - Operation

List of Illustrations

Figure 2-l
Figure 2-2
Figure 2-3
Figure 24
Figure 2-5
Figure 2-6
Figure 2-7
Figure 2-8
Figure 2-9
Figure 2-10

Figure 2-11
Figure 2-12
Figure 2-13
Figure 2-14

Figure 2-15
Figure 2-16

Figure 2-17

Figure 2-18

Figure 2-19

Figure 2-20

Figure 2-21

Figure 2-22

Figure 2-23

Figure 2-24

Figure 2-25

Figure 2-26

Matrix Card Installation ..........................................

Model7076 ....................................................

Simplified Component Layout
Model 7076 Configured as4 x 24 Matrix
Model7076Configuredas8x12Matrix
Column Jumper Installation
Single-ended Switching Example (Using 7075-MTC Cable)
Differential Switching Example (Using High Isolation Cables)
Driven Guard Example (Using High Isolation Cables)
Sensing Example (Using High Isolation Cables)
D-sub Receptacle Contact Assignments
Model 7075-MTC Standard Cable
D-sub Plug Pin Assignments for High Isolation Cables
Schematic Drawing of Backplane Jumper Configuration (Factory Default)
Narrow Matrix Example (4 x 72)

Dual4x72Matrices ............................

WideMatrixExample(8x36)
Partial Matrix Expansion (8 x 36)
Single Card System Example
Multiple Card System Example
Multiple Mainframe Example
Matrix/Multiplexer System

-3dB Bandwidth (Crosspoint Al closed, Rs = RL = 5OQ) ...................

-3db Bandwidth (Crosspoint HI2 closed, RS = RRL = 500)
Crosstalk (Crosspoints Gl and H2 closed, 5OQ source on ROW G, 500 load on

COLUMN l’, Measurements at ROW H)
Crosstalk (Cross

COLUMN 11, Mp

oints All and 812 closed, 5On source on ROW A, 5OQ load on

easurements at ROW B)

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2-3
24
2-5
2-6
2-7
2-8
2-8
2-8
2-9
2-9
2-10
2-12
2-14
2-16

.

2-17
2-18
2-18
2-20
2-21
2-22
2-23
2-24
2-25
2-25

2-26

2-26

SECTION 3 - Applications

Figure 3-l
Figure 3-2
Figure 3-3
Figure 34
Figure 35
Figure 3-6
Figure 3-7
Figure 3-8

Thick Film Resistor Network Testing

4-Terminal Ohms Measurements

Voltage Divider Checks . .
Transistor Testing . . .
Transistor Current Gain Checks .
Common Emitter Characteristics of an NPN Silicon Transistor
Transistor IE Measurements
Transistor VsEMeasurements

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.

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3-2
3-3
3-5
3-6
3-7
3-8
3-9
3-10

SECTION 4

- Service Information

Figure 4-l
Figure 4-2
Figure 4-3
Figure 4-4
Figure 4-5
Figure 4-6
Figure 4-7
Figure 4-8
Figure 4-9
Figure 4-10

Relay Test Setup . . . . . . . . .

Path Resistance Testing . . . . . . . . .

Common Mode Offset Current Testing
Differential Mode Offset Current Testing
Contact Potential Testing .
Path Isolation Testing (Guarded)
Differential Isolation Testing . . .

Common Mode Isolation Testing .
ID Data Timing Diagram
D-sub Receptacle Contact Assignments .

. .

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4-2
44
4-5
4-6
4-7
4-8
4-11
4-11
4-12
4-14

SECTION 2 - Operation

List of Tables

Table 2-1 Column Number Assignments

Table 2-2 4 x 24 Matrix Crosspoint Assignments . . . .

Table 2-3
Table 24 Cable Conductor Identification (Model 7075-MTC)
Table 2-5
Table 2-6
Table 2-7 Narrow Matrix Expansion* . . .
Table 2-8

Available Cables and Connectors

Model 7076.RMTC Conductor Identification
Model 7076~CMTC Conductor Identification .

Wide Matrix Expansion’ .

SECTION 4 - Service Information

Table 4-l Verification Equipment
Table 4-2 Path Isolation Tests
Table 4-3
Table 44
Table 4-5 Troubleshooting Summary”

Differential and Common Mode Isolation Test
Recommended Troubleshooting Equipment

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2-3
2-7
2-11
2-13
2-15
2-15
2-17
2-19

4-3
4-9
4-10
4-13
4-14

SECTION 1

General Information

1 .l INTRODUCTION

This section contains general information about the
Model 7076 General Purpose Matrix Card Dual 4 x 12.

1.2 FEATURES

The Model 7076 is a general purpose, two-pole, dual 4 x
12 (four row by 12 column) matrix card. Some of the key
feahxes include:

l Guard capability. Each HI path on the PC board is sur-

rounded by a second path that can be used for guard­ing.

l Low contact potential and offset current for minimal

effects on low-level signals.

. Quick disconnects using 2.5pin D-Sub connectors on

the rear panel.

. Row backplane jumpers. Cutting jumpers disconnects

rows from the Model 707 backplane.

l Column jumpers. Installing jumpers configures card

as an 8 x 12 matrix.

1.5 SAFETY SYMBOLS AND TERMS

The following symbols and terms may be found on an in­strument or used in this manual.

Then
should refer to the operating instructions located in the
instruction manual.

The
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 matrixcard. Such damage

may invalidate the warranty.

symbol on an instrument indicates that the user

f

symbol on an instrument shows that high voltage

1.3 WARRANTY INFORMATION

Warranty information is located on the inside front cover

of this instruction manual. Should your Model 7076 re­quire warranty service, contact the Keithley representa­tive or authorized repair facility in your area for further
information. When returning the matrix card for repair,
be sure to fill out and include the service form at the back
of this manual in order to provide the repair facility with
the necessary information.

1.4 MANUAL ADDENDA

Any improvements or changes concerning the matrix

card or manual will be explained in an addendum in­cluded with the unit. Be sure to note these changes and
incorporate them into the manual.

The terms COLUMN, COLUMNS, ROW and ROWS are

used in this manual as a reference to the rear panel recep­tacles of the matrix card.

1.6 SPECIFICATIONS

Model 7076 specifications may be found at the front of
this manual. These specifications are exclusive of the ma-

trix mainframe specifications.

1.7 UNPACKING AND INSPECTION

1.7.1

The Model 7076 is packaged in a re-sealable, anti-static
bag to protect it from damage due to static discharge and

Inspection for Damage

l-l

SECTION 1
General

Information

from contamination that could degrade its performance.
Before removing the card from the bag, observe the fol­lowing precautions on handling.

Handling Precautions:

1. Always grasp the card by the handle and side edges.
Do not touch the edge connectors and do not touch

board surfaces or components.

2. When not installed in a Model 707 mainframe, keep

the card in the anti-static bag and store in the origi­nal packing carton.

Afterremovingthecard fromitsanti-staticbag,inspectit
for any obvious signs of physical damage. Report any
such damage to the shipping agent immediately.

If you are going to install the card in the Model 707 main­frame at this time, be sure to follow the additional han­dling precautions explained in paragraph 2.2.

1.7.2 Shipping Contents

The following items are included with every Model 7076
order:

1.8 REPACKING FOR SHIPMENT

Should it become necessary to return the Model 7076 for
repair, carefully pack the unit in its original packing car­ton or the equivalent, and include the following informa­tion:

l Advise as to the warranty status of the matrix card.
l Write ATTENTION REPAIR DEPARTMENT on the

shipping label.

l Filloutandincludetheserviceformlocatedat theback

of this manual.

1.9 OPTIONAL ACCESSORIES

The following accessories are available for use with the
Model 7076:

Model 7075-MTC Standard RowlCohmn Cable
Assembly

The Model 707S-MTC is a three-meter (IO-feet), 24 con­ductor cable terminated with a 25-pin D-subminiature
(D-sub) connector on both ends. This cable connects to
either the ROWS or COLUMN receptacles on the rear
panel of the card. This cable assembly is constructed us­ing a general purpose flat cable that is fitted into a
shielded round jacket.

l Model 7076 Dual 4 x 12 Two-pole Matrix Card.
l Column jumper sets.
l Model 7076 Instruction Manual.
l Additionalaccessoriesasordered.Note that thecables

may be shipped in a separate packing carton.

1.7.3

Instruction Manual

The Model 7076 Instruction Manual is three-hole drilled
so that it can be added to the three-ring binder of the
Model 707 Switching Matrix Instruction Manual. After
removing the plastic wrapping, place the manual in the
binderafterthemainframeinstructionmanual.Notethat
a manual identification tab is included and should pre­cede the matrix card instruction manual.

If an additional instruction manual is required, order the
manual package, Keithley part number 7076-901-00. The
manual package includes an instruction manual and any
applicable addenda.

Thiscable iscommonly cut at a convenient length to pro­vide two separate cables. The cables can then be used to
connect to both the ROW and COLUMN receptacles. The
unterminated ends of the cables can then be connected to
instrumentation and DUTs.

Model 7076-RMTC HighIsolationRow CableAssembly

The Model 707GRMTC is a three meter (IO-feet), 2%con­ductor cable terminated with a 25pin D-sub connectors
onbothendsandisconfigured tomatetotheROWrecep-

tacle of the Model 7076. Each conductor pair (signal and

drain) of the shielded cable is wrapped with insulated

foil to minimize crosstalk between conductor pairs.

This cable is commonly cut at a convenient length to pro­vide two separate cables. The cables can then be used to
connect to both COLUMN receptacles. The unter­minated ends of the cables can then be connected to in­strumentation and DUTs.

l-2

General

SECTION 1

Information

Model 7076-Ch4TC High isolation Column Cable

Assembly

The Model 7076-CMTC is a 3-meter (lo-feet), 28-conduc-

tor cable terminated with a 25-pin D-sub connector on
both ends. This cable connects to either one of the two
COLUMN receptacles on the Model 7076. Each conduc­tor pair (signal and drain) of the shielded cable is

wrapped with insulated foil to minimize crosstalk be­tween conductor pairs.

This cable is commonly cut at a convenient length to pro­vide two separate cables. The cables can then be used to
connect to both COLUMN receptacles. The unter­minated ends of the cables can then be connected to in­strumentation and DUTs.

1-3

SECTION 2

Operation

2.1 INTRODUCTION

WARNING
The matrix configuration procedures in this
section should only be performed by quali­fied personnel who recognize shock hazards
and are familiar with the safety precautions
required to avoid possible injury. Review
the safety precautions found at the front of
this manual.

This section contains information on aspects of matrix
card operation and is arranged as follows:

2.2 Handling Precautions: Details precautions that
should be observed when handling the matrix card to en­sure that its performance is not degraded due to contami-

lMiOIl.

2.3 Card Installation and Removal: Covers the basic pro­cedure for installing and removing the card from the
Model 707 Switching Matrix.

2.4 Basic Matrix Configurations: Covers the basic matrix
configurations that the card can be configured for; dual 4
x 12 matrices, a single 4 x 24 matrix or a single 8 x 12 ma­trix.

2.5 Typical Matrix Switching Schemes: Explains some
of the basic ways that a matrix can be used to source or
measure. Covers single-ended switching, differential

(floating) switching, sensing, shielding, and guarding.

2.2 HANDLING PRECAUTIONS

To maintain high impedance isolation, care should be
taken when handling the matrix card to avoid contami­nation from such foreign materials as body oils. Such
contamination can substantially lower leakage resis­tances, degrading performance.

To avoid possible contamination, always grasp the card
by the handle and side edges. Do not touch the edge con­nectors of the card and do not touch board surfaces or
components. On D-subminiature (D-sub) connectors, do
not touch areas adjacent to the electrical contacts.

CAUTION
Do not store the card by leaning it against an
object (such as B wall) with its edge connec­tars in contact with a contaminated surface
(such as the flood. The edge connectors will
become contaminated, and tapes and solder
connections on the PC board may break as
the card bends. ALWAYS store the card (in
its anti-static bag) in the original shipping
carton.

Dirt build-up over a period of time is another possible
source of contamination. To avoid this problem, operate
the mainframe and matrix card in a clean environment.

If the card becomes contaminated, it should be tbor­oughly cleaned as explained in paragraph 4.2.

2.6 Connections: JXxwses the various methods and
techniques that can be used to connect DUTs and in&u­mentation to the matrix card.

2.7 Matrix Expansion: Discusses the various matrix con­figurations that are possible by using multiple cards. The

significance of backplane row jumpers on matrix con-

figurations is also covered here.

2.8 Typical Connection Schemes: Provides examples of
external connections for single card, multiple card and
multiple mainframe systems.

2.3 CARD INSTALLATION AND REMOVAL

WARNING
To avoid electrical shock that could result in
injury or death, ALWAYS remove power
from the entire system (Model 707, test in­struments, DUT, etc.) and discharge any ca­pacitors before doing any of the following:

1. Installing or removing the matrix card
from the mainframe.

2-1

SECTION 2
operation

2. Connecting or disconnecting cables from
the matrix card. The pins of the cable connec­tors are easily accessible making them ex­tremely hazardous to handle while power is

applied.

3. Making internal changes to the card (such
as removing or installing jumpers).

Cable connections to the matrix card make it difficult to

install or remove the card from the mainframe. Thus, it is

advisable to install the card and then make cable connec-

tions to it. Conversely, cables should be disconnected be­fore removing the card from the mainframe.

Referring to Figure 2-1, perform the following procedure
to install the Model 7076 matrix card in the Model 707:

CAUTION
Contamination will degrade the perform­ance of the matrix card. To avoid contamina­tion, always grasp the card by the handle and
side edges. Do not touch the edge connectors

of the card, and do not touch the board SUP

faces or components. On connectors, do not

touch areas adjacent to the electrical con-

tacts.

Turn the Model 707 off.
Select a slot in the mainframe and remove the cover­plate. The cover-plate is fastened to the mainframe
chassis with two screws. Retain the cover-plate and

screws for future use.

With the relay side of the matrix card facing towards

the fan, feed the card into the slot such that the top

and bottom card edges seat into the card edge guides

of the mainframe. Slide the matrix card all the way
into the mainframe and tighten the two spring
loaded panel fasteners.

4. To remove the card from the mainframe make sure
the Model 707 is off, power is removed from external
circuitry, and then reverse the above procedure.

2.4 BASIC MATRIX CONFIGURATIONS

A simplified schematic of the Model 7076 matrix card is
shown in Figure 2-2A. As shipped from the factory, the
matrix card is configured as two separate 4 x 12 matrices.
Each of the 96 crosspoints is made up of a two-pole
switch. By closing the appropriate crosspoint switch, any
matrix row can be connected to any column in the same
matrix. In this manual, the columns of every Model 7076
matrixcard arereferred to as columns 1 through 12 and 1’
through 12’. Columns 1 through 12 correspond to the col­umns receptacle (on the connection panel) labeled “TO
ROWS A-D”, while references to columns 1’ through 12
correspond to the columns receptacle labeled “TO ROWS
E-H”.

Note that even though there are 24 unique columns in
this configuration, the Model 707 recognizes only 12 col­umns for programming purposes. The crosspoint assign­ments for the matrix card are provided in Figure Z-28.
For example, to connect r6w A to column 10, the Model

707 would have to be programmed to close crosspoint
A10 (row A, column 10); and to connect row E to column
10’ (22nd column), crosspoint El0 would have to be
closed. These crosspoint closures assume that the matrix
card is installed in slot 1 of the mainframe. The crosspoint
assignments in Figure 2-2B are valid regardless of how
the card is configured.

The column number assignments for programming the
Model 707 are determined by the mainframe slot that the
matrixcard is installed in. For example, the column num­ber assignments of a matrix card installed in slot 4 of the
mainframe are numbered 37 through 48. Column num­ber assignments for all six mainframe slots are listed in
Table 2-1.

WARNING
The mounting screws must be secured to en­sure a proper chassis ground connection be­tween the card and the mainframe. Failure to
properly secure this ground connection may
result in personal injury or death due to elec­tric shock.

2-2

Notice in Figure 2-2A that there are backplane jumpers
located on the matrix card. With the jumpers installed,

the matrix card is connected to the backplane of the

Model 707 allowing matrix expansion (see paragraph

2.7). With the jumpers removed, the matrix card is iso­lated from any other cards installed in the mainframe.

The physical location of these jumpers on the board is

shown in Figure 2-3.

SECTION 2

Operation

Mounting Screws

Figure 2-1.

Matrix Card Installation

Table 2-l. Column Number Assignments

1 7076 Card Location 1

Slot 1
Slot 2
Slot 3
Slot 4
Slot 5
Slot 6

Card Handle

Matrix Column Numbers

1 through 12
13 through 24
25 through 36
37 through 48
49 through 60
61 through 72

2-3

SECTION 2

r-----

_------------

---

1

r----

A. Simplified Schematic

--------------

1

‘igure 2-2.

2-4

Model 7076

SECTION 2

Oaeration

I I

0 0

1 I I

I

l

.

Cigure 2-3. SimpIified Component layout

2.4.1

Figure 2-4 shows how the Model 7076 can be configured
as a single 4 x 24 matrix. Row jumper wires are used to
connect rows A, B, C and D to rows E, F, G and H respec­tively. These connections can be made wherever it is
most convenient, such as at the connector of a custom­ized cable ass$mbly, or at the instrumentation (see
Figure Z-15) or DUT test fixture.

In a multiple card system where badcplane jumpers are

left installed, row jumpers are only required at one card.

4 x 24 Matrix

r--------------------~

Removing the backplane jumpers will isolate the 4 x 24
matrix from any other card installed in the mainframe.

Crosspoint assignments for progmmming the Model 707
do not change even though the matrix configuration of
the card has changed (see Figure 2-28). For example, to
connectrowAtothe24th(12’)columnofthe4x24matrix
(see the equivalent circuit in Figure 2-4), the Model 707

would have to be programmed to close crosspoint El2

kmmingtbecardisinstaUedinslot 1 of themainframe).
Table 2-2 provides the crosspoint assignments for a
Mode17076 configuredasa4x24matrixinstalled inslot 1
of the mainframe. Table2-I provides the column number
assignments for the other mainframe slots.

Fmv

J”rnpers

\ I

I

I
I 1 2 3 4 5 6 7 I 8 Backplane

I

Column

Jumpers

TTTTTTTTI I II/~ I

Column

I

I

I
I
I
I

I

‘igure 2-4.

2-6

Equivalent Circuit

Model 7076 Configuredas 4 x 24Matri.r

Table 2-2. 4 x 24 Matrix Crosspoint Assignments

SECTION 2

Operation

M.&X Matrix Column

Row* 1

A(E) Al

B(F) Bl
C(G) Cl
D(H) Dl

2 3 . . . 12

A2 A3 A12

B2

c2

D2 D3 D12 Hl

E :::

B12

Cl2 Gl

1’ 2’ 3’ . . .

El
Fl

----------------_

r----

Column

E2
F2

E

12’

E3

E
H3 H12

:::

El2
F12

G12

1

2.4.2

Figure 2-5 shows that the Model 7076 can be configured
asastandard8~12matibyinstallingtbecolumnjump­em. The location of the column jumpers on the PC-board
is shown in Figure 2-3. As shipped from the factory, the

12columnjumperssetsarenotinstalled. Installingthe lated from any other card installed in the mainframe.

8 x 12 Matrix

jumpers sets,
Model 7076 as

With the Model 7076 backplane jumpers installed, the 8 x
12 matrix is connected to the backplane of the Model 707
allowing matrix expansion (see paragraph 2.7). With the
backplane jumpers removed, the 8 x 12 matrix will be iso-

as shown in Figure
an 8 x 12 matrix.

2-6, configures

the

2-7

SECTION 2
Operation

COI 1 Cal 1

Jumpers

H

. .
. .

Not Installed
(as shipped)

Note : See Fig. 2-3 for location

of jumpers on Pcboard.

?gure 2-6. Column Jumper Installation

2.5 TYPICAL MATRIX SWITCHING SCHEMES

The following paragraphs describe some basic switching
schemes that are possible with a two-pole switching ma­trix.

2.5.1

In the single-ended switching configuration, the source
or measure instrument is connected to the DUT through
a single pathway as shown in Figure 2-7. Note that the
shield of the Model 7075~MTC cable is connected to the
shield around the DUT.

Single-ended Switching

2.5.2 Differential Switching

The differential or floating switching configuration is
shown in Figure 2-8. The advantage of using this con­figuration is that the terminals of the source or measure
inslmment are not confined to the same matrix
crosspoint. Each terminal of the instrument can be con­nected to any matrix crosspoint. The guard terminals of
the matrix card are used as a shield.

Figure 2-7.

Source or

Measure

Single-ended Switching Example (Using 707.5MTC Cable)

7076

1

Shield

L---l

‘igure 2-8.

2-8

A Earth Ground

Diflerential Switching Example (Using High Isolation Cables)