Keithley 7077 Service manual
I
nstruction Manua
l
7
Model 707
Isolated Coaxial Matrix Card
Contains Operating and Servicing Information
7077-901-01 Rev. B / 4-97
WARRANTY
Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1 year from date of
shipment.
Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries,
diskettes, and documentation.
During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.
To exercise this warranty, write or call your local Keithley representativ e, or contact Keithley headquarters in Cleveland, Ohio. Y ou will
be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service facility. Repairs
will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for the balance of the original warranty period, or at least 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from product modification without Keithley’s express written consent, or misuse of
any product or part. This warranty also does not apply to fuses, software, non-rechargeable batteries, damage from battery leakage, or
problems arising from normal wear or failure to follow instructions.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN ARE
BUYER’S SOLE AND EXCLUSIVE REMEDIES.
NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT, INDIRECT , SPECIAL, INCIDENTAL OR CONSEQ UENTIAL 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: 216-248-6168 • http://www.keithley.com
CHINA: Keithley Instruments China • Yuan Chen Xin Building, Room 705 • 12 Yumin Road, Dewai, Madian • Beijing 100029 • 8610-62022886 • Fax: 8610-62022892
FRANCE: Keithley Instruments SARL • BP 60 • 3 Allée des Garays • 91122 Palaiseau Cédex • 33-1-60-11-51-55 • Fax: 33-1-60-11-77-26
GERMANY: Keithley Instruments GmbH • Landsberger Strasse 65 • D-82110 Germering, Munich • 49-89-8493070 • Fax: 49-89-84930787
GREAT BRITAIN: Keithley Instruments, Ltd. • The Minster • 58 Portman Road • Reading, Berkshire RG30 1EA • 44-118-9575666 • Fax: 44-118-9596469
ITALY: Keithley Instruments SRL • Viale S. Gimignano 38 • 20146 Milano • 39-2-48303008 • Fax: 39-2-48302274
NETHERLANDS: Keithley Instruments BV • Avelingen West 49 • 4202 MS Gorinchem • 31-(0)183-635333 • Fax: 31-(0)183-630821
SWITZERLAND: Keithley Instruments SA • Kriesbachstrasse 4 • 8600 Dübendorf • 41-1-8219444 • Fax: 41-1-8203081
TAIWAN: Keithley Instruments Taiwan • 1FL., 1, Min Yu First Street • Hsinchu, Taiwan, R.O.C. • 886-35-778462 • Fax: 886-35-778455
Model 7077 Isolated Coaxial Matrix Card
Instruction Manual
©1995, Keithley Instruments, Inc.
All rights reserved.
Cleveland, Ohio, U.S.A.
Second Printing, April 1997
Document Number: 7077-901-01 Rev. B
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 7077-901-01)................................................................................December 1995
Revision B (Document Number 7077-901-01)........................................................................................April 1997
All Keithley product names are trademarks or registered trademarks of Keithley 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
this product and any associated instrumentation. Although some instruments and accessories would normally be used with non-hazardous voltages, there are situations where hazardous conditions
may be present.
This product is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury. Read the operating information
carefully before using the product.
The types of product users are:
Responsible body is the individual or group responsible for the use
and maintenance of equipment, and for ensuring that operators are
adequately trained.
Operators use the product for its intended function. They must be
trained in electrical safety procedures and proper use of the instrument. They must be protected from electric shock and contact with
hazardous live circuits.
Maintenance personnel perform routine procedures on the product
to keep it operating, for example, setting the line voltage or replacing consumable materials. Maintenance procedures are described in
the manual. The procedures explicitly state if the operator may perform them. Otherwise, they should be performed only by service
personnel.
Service personnel are trained to work on live circuits, and perform
safe installations and repairs of products. Only properly trained service personnel may perform installation and service procedures.
Exercise extreme caution when a shock hazard is present. Lethal
voltage may be present on cable connector jacks or test fixtures. The
American National Standards Institute (ANSI) states that a shock
hazard exists when voltage levels greater than 30V RMS, 42.4V
peak, or 60VDC are present.
that hazardous voltage is present in any unknown circuit before
measuring.
A good safety practice is to expect
Users of this product must be protected from electric shock at all
times. The responsible body must ensure that users are prevented
access and/or insulated from every connection point. In some cases,
connections must be exposed to potential human contact. Product
users in these circumstances must be trained to protect themselves
from the risk of electric shock. If the circuit is capable of operating
at or above 1000 volts,
exposed.
As described in the International Electrotechnical Commission
(IEC) Standard IEC 664, digital multimeter measuring circuits
(e.g., Keithley Models 175A, 199, 2000, 2001, 2002, and 2010)
measuring circuits are Installation Category II. All other instruments’ signal terminals are Installation Category I and must not be
connected to mains.
Do not connect switching cards directly to unlimited power circuits.
They are intended to be used with impedance limited sources.
NEVER connect switching cards directly to AC main. When connecting sources to switching cards, install protective devices to limit fault current and voltage to the card.
Before operating an instrument, make sure the line cord is connected to a properly grounded power receptacle. Inspect the connecting
cables, test leads, and jumpers for possible wear, cracks, or breaks
before each use.
For maximum safety, do not touch the product, test cables, or any
other instruments while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge
any capacitors before: connecting or disconnecting cables or jumpers, installing or removing switching cards, or making internal
changes, such as installing or removing jumpers.
Do not touch any object that could provide a current path to the
common side of the circuit under test or power line (earth) ground.
Always make measurements with dry hands while standing on a
dry, insulated surface capable of withstanding the voltage being
measured.
no conductive part of the circuit may be
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
WARNING heading in a manual explains dangers that might
result in personal injury or death. Alw ays read the associated infor mation very carefully before performing the indicated procedure.
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 the 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.
The
CAUTION heading in a manual explains hazards that could
damage the instrument. Such damage may invalidate the warranty.
Ω
Ω
Ω
Specifications
MATRIX CONFIGURATION: 8 rows by 12 columns.
CROSSPOINT CONFIGURATION: 2-pole Form A (HI, LO).
CONNECTOR TYPE: BNC (HI, LO).
MAXIMUM SIGNAL LEVEL:
Any center or shield to any other center or shield: 42V peak, 1A switched.
DC SIGNALS: 30VA resistive load.
AC SIGNALS: 42VA resistive load.
COMMON MODE VOLTAGE: 42V peak, any terminal to chassis
CONTACT LIFE:
Cold Switching: 10
At Maximum Signal Level: 10
PATH RESISTANCE (per conductor): < 0.5 Ω , <1.5 Ω at end of contact life.
CONTACT POTENTIAL: <5 µ V per crosspoint (HI to LO).
OFFSET CURRENT: <100pA.
AC PERFORMANCE:
(Z
= Z
= 50 Ω ) <100 kHz <1 MHz
L
S
Insertion Loss
Crosstalk –65 dB –45 dB
1
Excludes loss caused by DC path resistance.
ISOLATION:
Path: >10
10
Differential: >10
Common Mode: >10
RELAY DRIVE CURRENT (per crosspoint): 28mA
RELAY SETTLING TIME: <3ms.
ENVIRONMENT:
Operating: 0 ° –50 ° C, up to 35 ° C at 70% RH.
Storage: –25 ° to 65 ° C.
8
closures.
1
0.05 dB 0.1 dB
, <75pF.
9
, <120pF.
9
, <200pF.
5
closures.
123456789101112
HLHLHLHLHLHLHLHLHLHLHLHL
H
A
L
H
B
L
H
C
L
H
D
L
ROW
H
E
L
H
F
L
H
G
L
H
H
L
Specifications are subject to change without notice.
COLUMNS
Model 7077
8x12 Isolated Coaxial Matrix
Backplane
Jumpers
(factory installed)
Table of Contents
1 General Information
1.1 Introduction..........................................................................................................................................................1-1
1.2 Features................................................................................................................................................................1-1
1.3 Warranty information...........................................................................................................................................1-1
1.4 Manual addenda...................................................................................................................................................1-1
1.5 Safety symbols and terms ....................................................................................................................................1-1
1.6 Specifications.......................................................................................................................................................1-1
1.7 Unpacking and inspection....................................................................................................................................1-2
1.7.1 Inspection for damage................................................................................................................................1-2
1.7.2 Shipping contents.......................................................................................................................................1-2
1.7.3 Instruction manual......................................................................................................................................1-2
1.8 Optional accessories.............................................................................................................................................1-2
2 Operation
2.1 Introduction..........................................................................................................................................................2-1
2.2 Basic matrix configurations .................................................................................................................................2-1
2.3 Typical matrix switching schemes.......................................................................................................................2-4
2.3.1 Single-ended switching..............................................................................................................................2-4
2.3.2 Differential switching ................................................................................................................................2-4
2.3.3 Sensing.......................................................................................................................................................2-4
2.4 Connections..........................................................................................................................................................2-5
2.5 Matrix expansion..................................................................................................................................................2-6
2.5.1 Backplane row jumpers..............................................................................................................................2-6
2.5.2 Narrow matrix expansion...........................................................................................................................2-8
2.5.3 Wide matrix expansion ..............................................................................................................................2-8
2.5.4 Partial matrix implementation....................................................................................................................2-9
2.5.5 Mainframe matrix expansion ...................................................................................................................2-10
2.6 Typical connection schemes ..............................................................................................................................2-10
2.6.1 Single card system ...................................................................................................................................2-10
2.6.2 Multiple card system................................................................................................................................2-10
2.6.3 Multiple switching matrix system............................................................................................................2-13
2.6.4 Matrix/multiplexer system.......................................................................................................................2-13
i
3 Applications
3.1 Introduction.......................................................................................................................................................... 3-1
3.2 Thick film resistor network testing...................................................................................................................... 3-1
3.2.1 Four-terminal ohms measurements............................................................................................................ 3-1
3.2.2 Voltage divider checks .............................................................................................................................. 3-3
3.3 Transistor testing ................................................................................................................................................. 3-3
3.3.1 Current gain checks ................................................................................................................................... 3-6
3.3.2 I
and V
E
measurements ......................................................................................................................... 3-7
BE
4 Service Information
4.1 Introduction.......................................................................................................................................................... 4-1
4.2 Handling and cleaning precautions...................................................................................................................... 4-1
4.3 Card installation and removal.............................................................................................................................. 4-1
4.4 Performance verification ..................................................................................................................................... 4-4
4.4.1 Environmental conditions.......................................................................................................................... 4-4
4.4.2 Recommended equipment ......................................................................................................................... 4-4
4.4.3 Path resistance tests ................................................................................................................................... 4-5
4.4.4 Offset current tests..................................................................................................................................... 4-6
4.4.5 Path isolation tests ..................................................................................................................................... 4-8
4.4.6 Differential and common model isolation tests....................................................................................... 4-10
4.5 Principles of operation....................................................................................................................................... 4-12
4.5.1 Card identification................................................................................................................................... 4-12
4.5.2 Switching circuitry................................................................................................................................... 4-12
4.5.3 Power up safeguard.................................................................................................................................. 4-13
4.6 Special handling of static-sensitive devices ...................................................................................................... 4-13
4.7 Troubleshooting................................................................................................................................................. 4-13
4.7.1 Recommended equipment ....................................................................................................................... 4-13
4.7.2 Troubleshooting procedure...................................................................................................................... 4-13
5 Replaceable Parts
5.1 Introduction.......................................................................................................................................................... 5-1
5.2 Parts list ............................................................................................................................................................... 5-1
5.3 Ordering information........................................................................................................................................... 5-1
5.4 Factory service..................................................................................................................................................... 5-1
5.5 Component layout and schematic diagram.......................................................................................................... 5-1
ii
List of Illustrations
2 Operation
Figure 2-1 Model 7077 simplified schematic and crosspoint assignments ...................................................................2-2
Figure 2-2 Simplified component layout .......................................................................................................................2-3
Figure 2-3 Single-ended switching example (using 4801 coaxial cable) ......................................................................2-4
Figure 2-4 Differential switching example....................................................................................................................2-4
Figure 2-5 Sensing example ..........................................................................................................................................2-4
Figure 2-6 BNC connector identification ......................................................................................................................2-5
Figure 2-7 Backplane jumper configuration (factory default).......................................................................................2-7
Figure 2-8 Model 707 backplane configured for row expansion...................................................................................2-7
Figure 2-9 Narrow matrix expansion (8 × 36)...............................................................................................................2-8
Figure 2-10 Wide matrix expansion (16 × 12).................................................................................................................2-9
Figure 2-11 Partial matrix example (16 × 24) .................................................................................................................2-9
Figure 2-12 Single card example................................................................................................................................... 2-11
Figure 2-13 Multiple card system example ...................................................................................................................2-12
Figure 2-14 Multiple switching matrix example – Model 707......................................................................................2-14
Figure 2-15 Multiple switching matrix example – Model 708......................................................................................2-15
Figure 2-16 Matrix/multiplexer system.........................................................................................................................2-16
3 Applications
Figure 3-1 Thick film resistor network testing .............................................................................................................. 3-2
Figure 3-2 Four-terminal Ω measurement.....................................................................................................................3-2
Figure 3-3 Voltage divider checks.................................................................................................................................3-4
Figure 3-4 Transistor checking ......................................................................................................................................3-5
Figure 3-5 Transistor current gain checks .....................................................................................................................3-6
Figure 3-6 Common emitter characteristics of an NPN silicon transistor.....................................................................3-7
Figure 3-7 Transistor I
Figure 3-8 Transistor V
measurements .........................................................................................................................3-8
E
measurements......................................................................................................................3-9
BE
4 Service Information
Figure 4-1 Matrix card installation ................................................................................................................................4-3
Figure 4-2 Path resistance testing ..................................................................................................................................4-6
Figure 4-3 Common mode offset current testing...........................................................................................................4-7
Figure 4-4 Differential offset current testing.................................................................................................................4-7
Figure 4-5 Path isolation testing (guarded)....................................................................................................................4-9
Figure 4-6 Differential isolation testing.......................................................................................................................4-11
Figure 4-7 Common mode isolation testing ................................................................................................................4-11
Figure 4-8 ID data timing diagram ..............................................................................................................................4-12
iii
List of Tables
1 General Information
Table 1-1 BNC cable lengths .......................................................................................................................................1-2
2 Operation
Table 2-1 Model 7077 column number assignments ...................................................................................................2-1
Table 2-2 Available Keithley cables and connectors ...................................................................................................2-6
Table 2-3 Narrow matrix expansion.............................................................................................................................2-8
Table 2-4 Mainframe matrix expansion – Model 707................................................................................................2-10
Table 2-5 Mainframe matrix expansion – Model 708................................................................................................2-10
3 Applications
Table 3-1 Minimum input impedance – Model 2000 DMM........................................................................................3-3
4 Service Information
Table 4-1 Verification equipment ................................................................................................................................4-4
Table 4-2 Path isolation tests........................................................................................................................................4-9
Table 4-3 Differential and common mode isolation test............................................................................................4-12
Table 4-4 Recommended troubleshooting equipment................................................................................................4-13
Table 4-5 Troubleshooting summary ......................................................................................................................... 4-14
5 Replaceable Parts
Table 5-1 Model 7077 electrical parts list....................................................................................................................5-2
Table 5-2 Model 7077 mechanical parts list ................................................................................................................5-3
v
1
General Information
1.1 Introduction
This section contains general information about the Model
7077 Isolated Coaxial 8 × 12 Matrix Card.
1.2 Features
The Model 7077 is a general purpose, two-pole, 8 × 12 (eight
rows by twelve columns) matrix card. Some of the key features include:
• Low contact potential and offset current for minimal effects on low level signals.
• BNC connectors to device under test (DUT) and instrumentation.
• Row backplane jumpers that isolate or connect matrix
rows from the Models 707 and 708 backplanes.
1.3 Warranty information
Warranty information is located on the inside front cover of
this manual. Should your Model 7077 require warranty service, contact your Keithley representative or an authorized
repair facility in your area for further information.
1.5 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 indicates high voltage
may be present on the terminal(s). Use standard safety precautions to avoid personal contact with these voltages.
The WARNING heading used in this manual explains dangers that might result in personal injury or death. Always
read the associated information very carefully before performing the indicated procedure.
The CAUTION heading used in this manual explains hazards that could damage the matrix card. Such damage may
invalidate the warranty.
The COLUMN, COLUMNS, ROW, and ROWS terms
used in this manual reference the rear panel receptacles of
the Model 7077 Matrix Card.
The Mainframe term used in this manual references the
Model 707 or Model 708 Switching Matrix.
1.4 Manual addenda
Any improvements or changes concerning the matrix card or
manual will be explained on an addendum. Addenda are provided in a page replacement format. Simply replace the obsolete pages with the new pages where indicated.
1.6 Specifications
Model 7077 specifications are located at the front of this
manual. These specifications are exclusive of the switching
matrix specifications.
1-1
General Information
1.7 Unpacking and inspection
1.7.1 Inspection for damage
The Model 7077 is packaged in a resealable, 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.
• Always grasp the card by the handle and side edges. Do
not touch edge connectors, board surfaces, or components.
• When not installed in a switching matrix, keep the card
in the anti-static bag and store 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 damage to
the shipping agent immediately.
If installing the card in a switching matrix at this time, be
sure to follow the additional handling precautions explained
in paragraph 4.2.
1.7.2 Shipping contents
The following items are included with every Model 7077 or der:
• Model 7077 Isolated Coaxial 8 × 12 Matrix Card.
• Model 7077 Instruction Manual.
• Additional accessories (as ordered). Note that the cables may be shipped in a separate packing carton.
1.8 Optional accessories
The following optional accessories are available from Keithley for use with the Model 7077:
Low noise triax cable
Model 237-ALG-2 — Low noise traix cable. A 2m (6.6ft.)
cable with a 3-slot male triax connector on one end and three
alligator clips on the other.
Low noise coaxial cable/cable kit
Model 4801 — Low noise coaxial cable. A 1.2m (48in.) cable with male BNC connectors on both ends.
Model 4802-10 — Low noise coaxial cable. A 3m (10ft.) cable with a male BNC connector end and an unterminated
end.
Model 4803 — Low noise coaxial cable kit. Includes 50ft. of
low noise coaxial cable, ten male BNC connectors, and five
female BNC chassis-mount connectors.
BNC adapter/shorting plug
Model 4804 — Male BNC to female triax adapter.
Model 4851 — BNC shorting plug.
Model 6147 — Male triax to female BNC adapter.
BNC Interconnect cables
The BNC interconnect cables, 50 Ω BNC to BNC (RG-58C),
are available in the lengths listed in Table 1-1:
Table 1-1
BNC cable lengths
Model number Length
1.7.3 Instruction manual
If an additional Model 7077 Instruction Manual is required,
order the manual package, Keithley part number 7077-901-
00. The manual package includes an instruction manual and
any applicable addenda.
1-2
7051-2
7051-5
7051-10
0.6m (2ft.)
1.5m (5ft.)
3.0m (10ft.)
Miscellaneous
Model 7754-3 BNC to alligator cable — 0.9m (3ft.) 50 Ω cable (RG-58C) terminated with a BNC plug on one end and
two alligator clips on the other end.
Model 7755 50 Ω feed-through terminator — BNC to BNC
adapter terminated with a 50 Ω resistor.
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 detailed information on matrix card operation.
2.2 Basic matrix configurations
A simplified schematic of the Model 7077 matrix card is
shown in Figure 2-1 (View A). Each of the 96 crosspoints is
made up of a two-pole switch. By closing the appropriate
crosspoint switch, any row can be connected to any column
in the same matrix. The columns of every Model 7077 matrix
card are referred to as columns 1 through 12, except where
noted.
The Model 707 or 708 recognizes 12 columns for programming purposes. The crosspoint assignments for the matrix
card are shown in Figure 2-1 (View B). To connect ROW A
to COLUMN 10, the Model 707 or 708 must be programmed
to close crosspoint A10 (R O W A, COLUMN 10). T o connect
ROW E to COLUMN 10, crosspoint E10 must be closed.
The crosspoint assignments in Figure 2-1 (View B) are valid
regardless of how the card is configured.
When installed in a multiple card switching matrix (Model
707), the column number assignments for programming the
Model 707 are determined by the switching matrix slot the
matrix card is installed in. For example, the column number
assignments of a matrix card installed in slot 4 of the switching matrix are numbered 37 through 48. Column number assignments for all six switching matrix slots are listed in T able
2-1.
Table 2-1
Model 7077 column number assignments
Matrix column
Card location
Slot 1
Slot 2
Slot 3
Slot 4
Slot 5
Slot 6
In Figure 2-1 (View A), 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 or 708
for matrix expansion (see paragraph 2.5). With the jumpers
removed, the matrix card is isolated from other cards or
switching matrices. The physical location on the board of
these jumpers is shown in Figure 2-2.
numbers
1 through 12
13 through 24
25 through 36
37 through 48
49 through 60
61 through 72
2-1
Operation
ROW
1234567891011 12
COLUMN
A
B
C
D
E
F
G
H
View A - Simplified schematic
Crosspoint (1 of 96)
H I
LO
Backplane
Jumper Sets (8)
1234567891011 12
A1
A
B
C
D
A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12
B1
B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12
C1
C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12
D1
D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12
ROW
COLUMN
E1
E
F
G
H
Note : Crosspoint assignments of Model 7077 Matrix Card shown above apply when installed in:
Model 708 Switching Matrix - Stand-alone or master of multi-unit configuration or
Model 707 Switching Matrix - Slot one of stand-alone or master of multi-unit configuration.
E2 E3 E4 E5 E6 E7 E8 E9 E10 E11 E12
F1
F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12
G1
G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12
H1
H2 H3 H4 H5 H6 H7 H8 H9 H10 H11 H12
View B - Crosspoint assignments
Figure 2-1
Model 7077 simplified schematic and crosspoint assignments
2-2
Operation
Figure 2-2
Simplified component layout
Backplane
Jumpers
2-3
Operation
2.3 Typical matrix switching schemes
The following paragraphs describe basic switching schemes
that are possible with a two-pole switching matrix.
2.3.1 Single-ended switching
In the single-ended switching configuration, the source or
measure instrument is connected to the DUT through a single pathway as shown in Figure 2-3. The closure of a single
crosspoint will connect an instrument to a DUT.
ROW COLUMN
HI
LO
Source or
Measure
H
L
7077
DUT
Figure 2-3
Single-ended switching example (using 4801 coaxial cable)
Shield
confined to the same matrix crosspoint. Each terminal of the
instrument can be connected to any matrix crosspoint. The
LO terminals of the matrix card are used as a shield. The closure of a single crosspoint will not connect an instrument to
a DUT.
ROWS COLUMNS
HI
LO
Source or
Measure
H
L
H
L
7077
DUT
System Common
Figure 2-4
Differential switching example
2.3.3 Sensing
2.3.2 Differential switching
The differential or floating switching configuration is shown
in Figure 2-4. The advantage of using this configuration is
that the terminals of the source or measure instrument are not
ROWS COLUMNS
Sense HI
Source HI
Sense LO
Source LO
Source or
Measure
Figure 2-5
Sensing example
Figure 2-5 shows how the matrix card can be configured to
use instruments that have remote sensing capability. Sensing
is used to cancel the effects of matrix card path resistance
(<1.5) and the resistance of external cabling. Remote sensing
should be used when path resistance needs to be considered.
H
L
DUT
H
L
7077
2-4
Operation
2.4 Connections
CAUTION
To prevent damage (not covered by the
warranty), do not exceed the maximum
allowable limits of the Model 7077.
Maximum signal levels are listed in the
specifications located at the front of the
manual.
All rows and columns of the Model 7077 Matrix Card are
connected to the BNC connectors mounted on the rear panel
of the matrix card when shipped. One receptacle is provided
for each row connection (rows A through H) and one for each
column connection (columns 1 through 12).
ROWS
1
A
2
B
C
D
E
F
G
H
3
4
5
6
7
8
9
10
11
12
BNC connector identification is provided in Figure 2-6. Each
BNC connector is internally connected to the adjacent corresponding row or column.
Cable connections
Available Keithley cables and connectors for customized
user supplied terminations are summarized in Table 2-2.
WARNING
To avoid electrical shock that could result in injury or death, ALWAYS remove
power from the entire system (Model
707 or 708, test instruments, DUT, etc.)
and discharge any capacitors before
connecting or disconnecting cables from
the matrix card.
1 2 3 4 5 6 7 8 9 10 11 12
A
B
C
D
E
F
G
H
COLUMNS
Model 7077
Figure 2-6
BNC connector identification
2-5
Operation
Table 2-2
Available Keithley cables and connectors
Model or part
number Description
237-ALG-2
4801
4802-10
4803
4804
4851
6147
7051-2 BNC to
BNC cable
7051-5 BNC to
BNC cable
7051-10 BNC to
BNC cable
7754-3 BNC to alligator cable
7755 50 Ω feedthrough terminator
Use the following procedure to connect a BNC cable to the
matrix card:
1. Install the matrix card in the Model 707 or 708 Switching Matrix (see paragraph 4.3).
2. Push the cables onto the appropriate receptacle of the
matrix card.
3. Tighten the BNC connector to secure it to the panel. The
same procedure can be used for connecting the cable
plug to a test fixture receptacle.
Low noise triax cable 2m (6.6ft.) in
length with a 3-slot male triax connector on one end and three alligator
clips on the other.
Low noise coaxial cable 1.2m
(48in.) in length with male BNC
connectors on both ends.
Low noise coaxial cable 3m (10ft.)
in length with a male BNC connector at one end and unterminated at
the other end.
Low noise cable kit. Includes 50ft.
of low noise coaxial cable, 10 male
BNC connectors, and 5 female BNC
chassis-mount connectors.
Male BNC to female triax adapter.
BNC shorting plug.
Male triax to female BNC adapter.
The Model 7051-2 is a 50 Ω
BNC cable (RG-58C) 1.5m (5ft.) in
length.
The Model 7051-5 is a 50 Ω BNC to
BNC cable (RG-58C) 1.5m (5ft.) in
length.
The Model 7051-10 is a 50 Ω BNC
to BNC cable (RG-58C) 3.0m
(10ft.) in length.
The Model 7754-3 is a 0.9m (3ft.)
50 Ω cable (RG-58C) terminated
with a BNC plug on one end and
two alligator clips on the other end.
The Model 7755 is a BNC to BNC
adapter terminated with a 50 Ω resistor.
BNC to
Modifying BNC terminated
A common way to use the standard cable is to cut it at a convenient length. The result is two cables that are both unterminated at one end. The unterminated ends of the cables can
then be connected to instrumentation and the DUT, and the
other ends can mate to the ROW and COLUMN BNC connectors of the matrix card.
WARNING
Due to the large amount of wiring that
switching systems contain, check that
both ends of the coaxial cable to be cut
are disconnected from instruments or
DUTs prior to performing this procedure. Cutting a connected cable may
cause severe injury or death due to electric shock.
2.5 Matrix expansion
By using additional matrix cards in the Model 707 or additional switching matrices in the Model 708, larger matrices
can be configured through the backplane of the Model 707 or
708. Therefore, unless otherwise noted, the examples provided in the following paragraphs assume the Model 7077
backplane jumpers are installed.
2.5.1 Backplane row jumpers
Matrix row expansion can be done through the backplane of
the Model 707 or 708 Switching Matrix. As explained in
paragraph 2.2, the Model 7077 has eight sets of backplane
jumpers that connect the rows of the matrix card to the
switching matrix backplane.
Model 707 switching matrix
The set of backplane jumpers located in the Model 707
Switching Matrix must be considered when building larger
matrices through rows. With the switching matrix backplane
jumpers installed, the rows of all switching matrix slots are
connected together. W ith these jumpers removed, the ro ws of
Model 707 Switching Matrix slots 1, 2, and 3 are isolated
from the rows of slots 4, 5, and 6.
2-6
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