Tektronix 5900 Instruction Manual

INSTRUCTION MANUAL

Digital Multimeter

Model 5900

WARRANTY

We warrant each of our products to be free from defects in material
and workmanship. Our obligation under this warranty is to repair
or replace any instrument or part thereof which, within a year after
shipment, proves defective upon examination. We will pay local

domestic surface freight costs.
To exercise this warranty, write or call your local Keithley repre-

sentative, or contact Keithley headquarters in Cleveland, Ohio.
You will be given prompt assistance and shipping instructions,

REPAIRS AND
CALIBRATION

Keithley Instruments maintains a complete repair and calibration
service as well as a standards laboratory in Cleveland, Ohio. A
service facility is also located in Los Angeles for our west coast
customers.

A Keithley service facility at our Munich, Germany office is
available for our customers throughout Europe. Service in the

United Kingdom’can be handled at our office in Reading. Addition-

ally, Keithley representatives in most countries maintain service

and calibration facilities.
To insure prompt repair or recalibration service, please contact

your local field representative or Keithley headquarters directly
before returning the instrument. Estimates for repairs, normal
recalibrations and calibrations traceable to the National Bureau of
Standards are available upon request.

KEITHLEY

The measurement engineers.

Keithley Instruments, inc., 28775 Aurora Road, Cleveland, Ohio 44139. [phone]

European Headquarters: Heiglhofstrasse 5, D-8000 Munchen 70 West Germany, [phone]

Unlted Kingdom: 1 Boulton Road, Reading, Berkshire, [phone]

France: 44 Rue Anatole France. F-91121 Palaiseau (01) 928-00-48

FOR YOUR SAFETY

Before undertaking any maintenance procedure, whether it
be a specific troubleshooting or maintenance procedure
described herein or an exploratory procedure aimed at
determining whether there has been a malfunction, read the
applicable section of this manual and note carefully the
WARNING and CADTlON notices contained therein.

The equipment described in this manual contains voltages
hazardous to human life and safety and which is capable of
inflicting personal injury. The cautionary and warning
notes arc included in this manual to alert operator and
maintenance personnel to the electrical hazards and thus
prevent personal injury and damage to equipment.

If this instrument is to be powered from the AC Mains
through an autotransformer (such as a Vartac or equivalent)
ensure that the instrument common connector is con­nected to the ground (earth) connection of the power
mains.

Before operating the unit ensure that the protective con­ductor (green wire) is connected to the ground (earth)
protective conductor of the power outlet. Do not defeat

the protective feature of the third protective conductor in

the power cord by using a two conductor extension cord or
a three-prong/two-prong adapter.

Maintenance and calibration procedures contained in this
manual sometimes call for operation of the unit with power
appliedandprotective covers removed. Read the procedures
carefully and heed Warnings to avoid “live” circuit points
to ensure your personal safety.

Before operating this instrument,

1. Ensure that the instrument is configured to
operate on the voltage available at the power
source See Installation section.

Ensure that the proper fuse is in place in the

2.
instrument for the power source on which the
instrument is to be operated.

3. Ensure that all other devices connected to or in
proximity to this instrument are properly grounded
or connected to the protective third-wire earth

ground.

COPYRIGHT

0

Copyright
States of America.
not be reproduced in any form without written permission of the
publishers.

1976 by Keithley Instruments, Inc. Printed in the United

All rights reserved. This book or parts thereof may

PROPRIETARY NOTICE

This document and the technical data herein disclosed, are proprietary

to Keithley Instruments, Inc., and shall not, without express written
permission of Keithley Instruments, Inc., be used, in whole or in part
to solicit quotations from a competitive source or used for manufacture
by anyone other than Keithley Instruments, Inc. The information
herein has been developed at private expense, and may only be used for
operation and maintenance reference purposes or for purposes of
engineering evaluation and incorporation into technical specifications
and other documents which specify procurement of products from

Keithley Instruments, Inc.

TABLE OF CONTENTS

Section

1

1.1

1.7

1.9

1.11

1.13

1.15

1.17

1.19
I .26
I .32

2

2.1

2.4

2.6

2.8

2.12

2.13

2.16

2.18

2.19

2.21

2.23

2.24

2.28

2.42

2.44

2.46

2.48

2.50

2.54

2.56

2.59

2.60

2.62

2.64

2.66

2.68

2.70

2.72

2.75

2.77

GENERALDESCRIPTION

Introduction

Options .’

Model 42 Remote Programming

Rear Input Options(-I, -1s)

Rack-Mounting Flanges (403402)
High-Voltage Probe
Current Shunt Set (651)

Electrical Description
MechonicalDescription
Specifications

mSTALLATION& OPERATION
Unpacking and Inspection
Bench Operation
Rack Mounting
Power Connections
Input/Output Cabling

Binding Posts
Rear Input Connector

Manual Operation

Controls

Display ...............

Measurement Connections.

Basic Voltage Measurement

Ohms Measurement

Ratio Measurements
System Capabilities

Printer Output
Program Input.

Logic Levelsand Electronic Interface

Driving the Inputs
TTL Loading Conditions

Exceptions to Input Loading Conditions

‘ITL Output Capabilities
Thning Sequence
Other Read CommandOptions
Reading Rates.

Superfast

Printer Output

Numerical Data

Function Data.

Range Data.

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

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

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

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

. JZOI .........

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

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

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

.........

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

..........

.........

...........

........

.......

..........

..........

...........

...........

..........

........

........

...........

......

...........

...........

...........

Title Page

. .

.....

...

I-1
1-l
I-I
I-1
I-1

1.2
1-2
l-2
1-2
I.3
l-3

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

2.4
24
24
2-7
2-7
2-8
2-8
2-8
2-B
2-8

2.10
2-10

2.10

2.11
2-12

2.12
2-13
2-13

‘2.14

2.14

111

980453

Section

TABLE OF CONTENTS (continued)

2.79

2.81

2.83

2.84

2.86

2.88

2.90

2.93

2.95

2.97

“NO” Indication
Status Output Lines

Input Control Lines
System Direct Command
Remote Programming
SystemControl

Function Programming

Range Programming

+ Five Volts

Hold

2.99 Read Commands

2.101

2.103

2.105

2.107

2.109

Timeouts

Data Inhibit
Program Storage

Superfast

Adding/Removing Accessories

3 SPECIFICATIONTESTS .....

3.1

3.4

3.6

4

4.1

4.3

4.5

4.7

General ...........

Required Equipment ......

Procedure ..........

THEORY OF OPERATION
General

Mechanical Description
Electrical Description
Signal Conditioning Section

4.10 Switching Board

4.14

4.18

4.2 1

4.24

4.28

4.30

4.33

4.35

4.37

4.52

4.54

4.56

4.70

4.12

4.74

OhmsConverter
Scaling Atnplifier
Averaging AC Converter

RMSACConverter
Attenuator
Isolator
Switching Bypass.

Integration

Digitizer,

Ratio, Standard
Ratio,Option
Display Board

Main Logic and Control Circuitry

Control Logic
Program Cycle

. .

2.14

2.15
2-15

2.16

2.16

2.16

2.16

2.17

2.17
2-17

2.17

2.17
2-17

2-17

2.18

2.18

3.1
3-l
3-l
3-1

4.1
4-l

4-l
4-l
4-1
4-l
4-1

4.3

4.9
4-9

4.9

4.9
4-9
4-9

4.12
4-14

4.15

4.15

4.17
4-17

4.19

iv

TABLE OF CONTENTS (continued)

980453

Section

4.76 Display Logic

4.78 Superfast

4.80

4.82
5

5.1

5.3

Power Supplies
Program.

CALIBRATION
scope

General

5.5

5.7

5.10

5.19

5.23

Preliminary Procedure

5.24

5.26

5.28

5.30

5.32

Recalibration Procedure .

5.34

5.35

5.36

5.38

DC Range Calibration
Ohms Calibration.

5.39

5.40

5.41

Ohms Range
AC Calibration (Model 33).

5.42

5.43

5.44

5.45

5.46

RMS AC Calibration (Model 32)
4-Wire Ratio Calibration
Troubleshooting

5.48

5.50

5.52

5.54

5.55

5.86

Board Revision

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

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

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

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

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

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

Required Equipment

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

Fabricated Calibration Equipment

DC Voltage Sources

AC Voltage Sources

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

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

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

Warmup.

Familiarization
Calibration Points
Environmental Considerations

Isolator Zero

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

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

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

...........

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

DC Voltage Zero and Gain.

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

ohms Zero

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

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

AC Converter Zero

Frequency Response

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

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

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

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

Troubleshooting Equipment

Power Supply Check

Operational Check

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

Preliminary Instrument Setup
Circuit Descriptions

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

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

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

...........

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

Title

..........

4-19

4.19

4.19

4.20
5-1

5-l

5-l

5-l
5-l
5-l

5-4

5-4
s-4
54
54
5-4

54

5-6
5-6
5-6
5-6

5.6
5-7

5.7

5.7
s-7
5-9

s-10

s-10
s-10
S-10
5-l 1
5-1 1

5.11
s-14

1

DRAWINGS . . . . .

PARTS LIST . . . . . . . . . . .

6-1
7-1

v/vi blank

LIST OF ILLUSTRATIONS

Figure

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

2.10

2.11

2.12

2.13

2.14

2.15

2.16

2.17

4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

4.10

4.11

4.12

4.13

4.14

4.15

4.16

4.17

5.1

5.2

5.3

5.4

5.5

5.6

5.7

5.8

5.9

1.1

1.2

Block Diagram -Model 5900
Dimensions,
Rack Mount Installation’
Cabling Diagram, Binding Posts
Cabling Diagram, Rear Input
Readout
Front Panel
Basic Voltage Measurement Connections
Maximum RMSlnput Voltage
Two Wire Ohms Measurements
Four Wire Ohms Measurement
Rear Panel
Measurement Sequence.
Command Timing
Minimum Read Rate vs. Input
Superfast Read Rate (Worst Case)
Pin Assignments 5201 PRINTER OUT

Pin Assignments 5202 PROGRAM INPUl
Jumper Location

Mechanical Assembly
Signal Flow, Loaded DVM.
Switching Board
Signal Flow of Switching Board

Ohms Converter

OhmsMeasurement Systems
Scaling Amplifier
Averaging AC Converter

RMS AC Converter
Attenuator/Isolator DC.
Signal Flow, Switching Bypass
Digitizer.

Integration Timing Diagram

4.Wire Ratio Option
Display Board
Main Logic&Control Block Diagram
Program Block Diagram.

10 Volt Source
Generating Accurate DC Levels
AC Source

Adjustment Locations

Ohms Input Connection

Connections for Ohms Range Adjustment

4.Wire Connections
AC Adjustment Locations

4.Wire Ratio Adjustment Locations

Title Page

l-2

l-3
2-l
2-2
2-2
2-2
2-3

2.4
2-4
2-s
2-6
2-8
2-9

2-11

2.12

2.13
2-14
2-16

Z-IX

4-2

4.3
4-4

4.5
4-6
4-7
4-R
4-8

4.10

4.11

4.12
4-13

4.14
4-1s

4.15
4-18

4-20

5-2
s-2
s-3
s-s
S-6

5.7
s-7
S-8

S-IO

vii

980453

LIST OF ILLUSTRATIONS (continued)

Figure

6.1

Layout, Logic and Interconnection

6.2 Layout, Readout

6.3

6.4

6.5

6.6

6.7

6.8

Schematic, Logic and Interconnection ..........

Schematic, Power Supply

Layout, Attenuator
Schematic, Attenuator
Layout, Switching
Schematic, Switching

6.9 Layout, Isolator

6.10

6.11

6.12

Schematic, Isolator

Layout, IOV Reference Amplifier
Layout, Digitizer

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

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

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

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

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

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

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

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

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

...........

...........

6.13 Schematic, Digitizer and 1OV Reference Amplifier ......

6.14

Layout, Program

6.15 Schematic, Program

6.16

layout, Display

6.17 Schematic, Display

6.18

6.19

6.20

Layout, AC Converter

Schematic, AC Converter

Layout, RMS Converter

6.21 Schematic, RMS Converter

6.22

6.23

Layout, Scaling Amplifier
Schematic, Scaling Amplifier

6.24 Layout, Ohms Converter

6.25 Schematic, Ohms Converter

6.26

Layout, 4.Wire Ratio

6.27 Schematic, 4.Wir-s Ratio

6.28 Layout,RearPanel

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

6.29 Layout, Parallel Front-Rear Input (-1) ..........

6.30 Layout, Switchable Front.Rear Input (-IS) ........

Title

Page

6-3

6.3
6-S
6-7

6.8

6.9
6-10
6-11

6.12

6-13

6.14

6.14
6-15

6.16

6.17

6.18

6.19

6.20
6-21

6.22

6.23

6.24

6.25
6-26
6-27

6.28

6.29

6.30

6.3 1
6-32

viii

LIST OF TABLES

Table

1.1

1.2

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

3.10

3.11

3.12

4.1

4.2

4.3

4.4

4.5

4.6

4.7

5.1

5.2

5.3

5.4

5.5

5.6

5.7

5.8

5.9

5.10

7.1

7.2

Measurement Capability
Specifications
Operating Controls
Maximum Input Voltage
Positive True Logic Relationships
Range Codes(Printer Output)
Function Programming
Range Codes(Programmet)
Timeouts
Maximum Input Voltage
Required Equipment
DC Range Check(Low Ranges)
DC Range Check (High Ranges)

3.Wire Ratio Check

4.Wire Ratio Check
DC Input Resistance.
Model 33 AC Converter Range Check
Model 32 AC Converter Range Check
Ohms-Megohms Range Check.
Common Mode Rejection (In DC Volts Function)
Normal Mode Noise Rejection (In DC Volts Function)
Common Mode Rejection (In AC Volts Function)
Switching Board Range Decode
Range Switch Code
Autorange Logic
Relay Logic Coding
Annunciator Logic

“NO” Annunciator Logic
Program Logic Conversion
Required Calibration Equipment
Fixed Voltage Dividers
DC Source Accuracies
AC Source Accuracies
Power Supply Check
OperationalCheck

Trollblesllooting Guide
Troubleshooting Chart-Digitizer and 1OV Reference Amplifier
Troubleshooting Chart. Isolator and Attenuator Boards
Troubleshooting Chart

Table7.1
List of Suppliers

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

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

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

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

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

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

.............. 1 1 : : 1 1 1 1 1 1 1 1 1 :

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

............... : : : : : : : : : : : ,: : : : :

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

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

.......... : : : : : : : : : : : : : : : :

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Optional Accessories

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

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

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

: : : : : : : : : : : : : : :

............. : : :

: : : : : : : : : : : : : : :

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

: : : : : : : : :

: : : : : : : : : : : : :

: : : : : :

: : : :

: : : : : : : : :

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

Page

1-1
1-4

2.3

2.4
2-a

2.15

2.17

2.17
2-18

2.18
3-1

3.2
3-3
3-4
3-s

3.6
3-7
3-8

3-9
3-10
3-11

3.12

4-1

4.16
4-16

4.16

4.17

4.17
4-2 1

5-a
S-l
s-3
s-4

S-II
s-1 1
s-12
s-13
s-14

s-14

7-1
7-l

980453

ix

SECTION 1

GENERAL DESCRIPTION

1.1 INTRODUCTION.
The Model 5900 Digital Multimeter is a five-decade

1.2
instrument with a sixth digit providing 60% overrange. The
basic instrument is equipped for dc and dc/dc ratio meas­urements on five ranges. With the addition of the optional
AC Converter, a-c and ac/dc ratio measurements on four
ranges are available. The Ohms Converter, also optional,
adds ohms measurements on eight ranges. Complete meas­urement capability of a fully equipped instrument is tabu­lated in table 1 .l.

Table 1 .I - Measurement Capability

r

DC & Dc/Dc

RATIO

Range (Basic 5900)

.lV I x I

1vI x I

I

1ov X

FUNCTION

OhIllS

(Model 52

Ohms

Converter)

I

AC & AC/DC

RATIO

(Model 32

or 33

AC Converter)

1

IOOV I x I

ooov I x I

100.

I

.I KS2 X

I x

until a single reading is commanded by an external com­mand. The new measurement is then held until the next
external command. In Periodic mbde (RATE control CW),
measurements are made automatic+ly at the rate of approxi­mately four per second.

1.5 The basic Model 5900 includes an analog output
voltage that is proportional to the parameter being meas­ured (except ratio). The voltage, at 20 volts maximum, is
available at a rear panel connector.

Also included as standard equipment is a solid-state

1.6
isolated BCD output. TTL-compatible output levels of the
reading, function, range, etc., plus a print command are
provided. An additional line enables a new reading to be
commanded externally. An optional isolated remote pro.
gramming unit (Model 42) allows all operating commands to
be made extcmally.

1.7 OPTIONS.

1.8 All optional accessories having model numbers are
plug-in circuit boards that may be added at any time. A
calibrated accessory board can be installed without af­fecting the d-c calibration of the basic instrument. An
instrument shipped without PCB accessories will not be
equipped with a Function Switching PCB assembly. This
board must be added when accessory boards are installed.
Analog accessories are identified in table 1 .l.

1Kn

10Kn 1

100 K$-l 1

000 KS2 1

lOMa/

lOOMa 1

1.3 Range can be selected manually or automatically
(autorange).
ular measurement is selected automatically (full scale is de­fined as “100000” on any range). The instrument “up
ranges” at 16U% of full scale and “downranges” at 15% of
full scale. Polarity selection is also automatic and is dis­played on the readout.

1.4

(RATE control on EXT), a measurement is held (displayed)

In AUTO range, the proper range for a partic-

Two operating modes are provided. In Hold mode

X
I x
I x

I x
I x

I x

Model 42 Remote Programming.

1.9
The Model 42 Remote Programming accessory al-

1.10

lows the selection of function, range, filter, read command,
etc., to be made externally. Auto range selection is also
provided and appropriate timeouts are generated internally
when ranging takes place. Remote Programming “overrides”
all manual control settings to prevent erratic selections.
Complete isolation of the programming unit is achieved by
the use of photoauplers and pulse transformers.

1.11 Rear Input Options (-1, -lB, -1s. -1SB).

1.12

5900 DMM. The option designated -1 or -IB consists of
connector 5204 on the back panel with input lines +
INPUT, + CURRENT, and GUARD wired in parallel with
the front panel input terminals; the option designated -1s
or -1SB is the same as the -1 or -lB except that the front or
rear inputs are selectable by a switch on the front panel.

Two rear input options are available for the Model

b

I-I

980453

T T

1.13 Rack-Mounting Flanges (403402).

1.14 Rack.Mounting Flatages are used where 1111’ IIIS~~U-

ment is to be installed in a relay-rack or cabinet.

1.15 High-Voltage Probe (641).

1.16 The High.Voltage Probe extends the voltage range of
the instrument up to 10,000 volts (or 7SOOV rms). It is an
insulated prube containing a 1000: 1 voltage divider.

l-2

1.17 Current Shunt Set (651).
I .I8 The Current Shunt Set consists of six precision

sIllill assemblies witb values selected to produce a voltage
drop that, n~e:tsured in millivolts. Ins a numerical value
cqual to 111~ current Ilow in milliamps or micro;tmps.

1.19 ELECTRICAL DESCRIPTION.

1.70

1be Model 5900 DMM is a dual slope integration

instrument consisting of three main functional areas: signal

9804.53

conditioning, integrating, and control/display. A block dia­gram of the instrument is shown in figure I, 1.

1.21 The signal conditioning section includes the
Switching p-c board, AC Converter, Ohms Converter,
Attenuator, and Isolator. The function of these circuits is
to convert the incoming signal to 10 MC, full scale into the

integrator.

1.22 The Integrating section consists of the Integrator

amplifier, Null Detector and + reference voltages. The
function of these circuits is to convert the conditioned in.
put signal to an equivalent time period and to transmit this
iime period to the display portion of the DMM.

1.23 Dual slope integration operates as follows in a

sequence of program (PCM) states:

a. Signal Integration (KM-A). The integrator capaci-

tor charges to a voltage proportional to the input

voltage during a 20 msec sampling period.

b. Reference Integrate (KM-C). During this period,

the integrator capacitor discharges at a constant cur­rent. The time that the integrator requires to dis­charge (full discharge detected by the Null Detector)
is measured by the counter. The data in the counter
at the end of PCM.C is proportional to the input
voltage.

1.28 The Function Switching board is used only when

either or both of the options (AC and Ohms) are installed.

With no options installed, the Function Switching board is

replaced with the Switching Bypass board. The Switching
Bypass merely connects the + Input (from input connector)
directly to the Isolator input and the - Input to ground.

1.29 At the rear edge of the Logic and Interconnection
assembly is a PCB connector that extends to the rear panel
and serves as the BCD output connector 1201. If the

optional Remote Program board is installed, it is mounted

on stand-offs above the Logic and Interconnection board

with the PROGRAM INPUT connector (J202) available at

the rear panel above the BCD OUTPUT connector.

1.30 The POWER input connector 1203, the power trans­former, and power transistors for the power supply are

mounted on the rear panel of the instrument. Other power

supply components are mounted on the Logic and Inter-

connection assembly. Also mounted on the rear panel, in
addition to .I201 and 1202, is the rear INPUT connector
J204, the ANALOG OUTPUT connector and common, the

EXTernal REFerence connector and common, and the line

fuse F201,

1.31 A dimensional outline of the Model 5900 is shown

in tigure 1.2.

c. Strobe @CM-D). At this time, data in the counter

is strobed into the storage latches and displayed -

the print pulse is inhibited, however if an uprange
or downrange command is generated by the Auto­range logic. If a range change is required, the

counter is reset and the program returns to PGM-A.

d. Reset @‘CM-E). At PCM-E, all internal logic is reset

in preparation for the next reading.

1.24 An additional control state, PGM.B, occurs after
PGM-A and is a delay to allow for propagation time of the
counter.

1.25 The Control/Display section generates the control
signals necessary to operate the signal conditioning and
integrating circuits.

1.26 MECHANICAL DESCRIPTION.

1.21 The ohms measurement option consists of a single
printed-circuit board. The AC options both consist of two
boards. The accessory boards plus the Digitizer, Isolator,

and Function Switching board all plug into the Main Logic

board called the Logic and Interconnection assembly. This

board also carries much of the instrument logic.

Figure 1.2 Dimensions

1.32 SPECIFICATIONS.

1.33 Specifications are listed in table 1.2.

1-3

980453

Table 1.2 - Specifications

SPECIFICATIONS, MODEL SSOO

AS A DC VOLTMETER IBASIC INSTRUMENTl

RATIO tdcldc. mVldc. acldc)

SPECIFICATIONS CONTINUED NEXT PAOE

Table 1.2 -Specifications (continued)

980453

l-5

SECTION 2

2.1 UNPACKING AND INSPECTION.

INSTALLATION & OPERATION

2.2
plastic-foam form within a cardboard carton for shipment.
The plastic form holds the DMM securely in the carton and
absorbs any reasonable external shock normally encountered
in transit. Prior to unpacking, examine the exterior of the
shipping carton for any signs of damage. Carefully remove
the DMM from the carton and inspect the exterior of the
instrument for any signs of damage. If damage is found,
notify the carrier immediately.

2.3 Included with the instrument in the packing con­tainer are the instruction manual, power cord, and rear in­put and BCD output mating connectors. With instruments
equipped with remote programming, a mating connector
for that accessory is included.

2.4 BENCH OPERATION.

2.5 Each Model 5900 is equipped with a tilt bail or
“kickstand” to enable the front of the instrument to be
elevated for convenient bench use. The tilt bail is attached
to the two front supporting “feet” at the bottom of the
instrument. For use, the bail is pulled down to its sup­porting position.

The Model 5900 DMM is packed in a molded

2.6 RACK MOUNTING.

2.1 The instrument can be mounted in a standard 19.
inch rack with the optional rack-mounting flanges (403402,
includes attaching hardware). To install the flanges, pro­ceed as follows:

a. With instrument on its side, remove four Phillips-

head screws holding bottom cover. Remove cover.
Remove screws holding feet (and bail) in place. Re­place bottom cover.

b. Place one of the supplied screws through each of

the two holes in the mounting flange (figure 2.1).

Thread a securing nut onto each screw just enough

to attach it to the screw (approximately one turn).

c. Place the mounting flange onto the mounting slot

in the instrument side panel so that the securing
nuts fit entirely into the slot. Be sure the rack­mount slots on the flange are toward the front of
the instrument.

d. Tighten screws. The securing nuts will rotate and

hold the flange securely in place.

2.6 POWER CONNECTIONS.

2.9 Standard units operate on either 1 IS volts or 230
volts, SO to 60 Hz (400 Hz available). Power consumption
is less than 40 watts. Operation on either of the two line
voltages is selectable by a slide switch on the rear panel.
Operation on lOO/ZOO volts or 1201240 volts is possible by
simple rewiring of the power transformer secondary wires:

WARNING
Disconnect the instrument from the AC Power source
before attempting to change power connections.
Potentially lethal voltages are exposed when covers
are removed.

a. For operation on 100/200 volts, cut the brown wire

1” from the transformer and splice it to the red
wire on the transformer; cut the blue wire 1” from
the transformer and splice it to the violet wire.

b. For operation on 120/240 volts, cut the brown

wire 1” from the transformer and splice it to the
black wire; cut the blue wire and splice it to the
yellow wire on the transformer.

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980453

2.10 A standard power cable having a three-pin plug is
supplied with the instrument. It connects to POWER con.
nectar 5203. The ground pin (round) is attached to the

instrument case. It is important that this pin be connected

to a good quality earth ground.

2.1 I

Fuse receptacle F20l on the rear panel is equipped

with a .5 amp fuse in domestic units.

2.12 INPUT/OUTPUT CABLING.

2.13 Binding Posts.

2.14 Several connectors on the Model 5900 consist of a
pair of binding posts spaced so as to accept standard
“banana” plugs. The connectors are:

I

Front Panel

I

Rear Panel

+ INPUT f. ANALOG OUTPUT

+ OHMS CURRENT

?1 REFerence INput

2.15 Input cables to fit this type of connector can be
ordered from Keithley (P/N 5900-402190). Figure 2.2 is a
wiring diagram of this cable included for assistance to users
desiring to construct their own cables.

panel binding posts. The rear-panel input lines are wired in
parallel with the front-panel input lines. It is recommended
that the cable for the mating connector be constructed as
shown in figure 2.3 using two two-conductor shielded
cables. Other configurations may be desirable depending
on the ohms measuring method to be used (see para­graph 2.28).

I

2.18 MANUAL OPERATION.

2.19 Controls.

2.16 Rear Input Connector.

2.17 Instruments equipped with the -I or -IS rear input
option are supplied with 5204 7.pin input connector

(Keithley P/N 5900-600673) and a mating connector

(Keithley P/N 5900-600616). The instrument acceptsinputs

applied to this connector or inputs applied to the front-

2.20 All operating controls are located on the front panel
of the instrument. They are shown in figure 2.5 and their
operation described in table 2.1. Description of Systems
operation begins in paragraph 2.44.

2.21 DISPLAY.

2.22 The Pisplay consists of 6 LED decimal readout
devices with moving decimal point. The decimal point

moves in conjunction with the range switchor automatically

in auto range. Maximum usable readout with overrange is

159999. Overload is indicated by a NO and 160000 read­out. A non-compatible range and function is indicated by
a NO. However, mechanical interlocks are provided to pre­vent illegal combinations from the front panel. Figure 2.4
illustrates the readout, NO indicator, polarity sign and the

DC MO

+

r /--- r-7 ,---I ,---I ,--1 AC

- I L-, L-4 L-4 L-,’ L-4 PGM
NO,’ --J. ,’

Fiwe 2.4 . Readout

: : :

KO

n

FIL R

2-2

Figure 2.5 -Front Panel

Table 2.1 . Operating Controls

Control

POW1

(rocker switch)

Function Select

(rotary switch)

Range Select
(rotary switch)

DATA OUTPUT
(pushbutton)

Position

ON (UP)
OFF (down)

ACT

DC

AUTO

Other Positions

Depressed

Function

Applies power to instrument

Removes power from instrument

Selects the measurement of AC voltages on the I, IO, 100, and

1000 volt ranges (max. input, 1OOOV RMS)

Selects the measurement of DC voltages on the .l, 1, IO, 100,
and 1000 volt ranges (max. input, IlOOV)

Selects the measurement of resistance on the 10 ohm range; on
the.1,1,10,100,andlOOOkilohmsranges;oronthe10or100
Megohm ranges

Selects Auto Range in which the optimum range is selected auto­matically by internal circuits. Uprange occurs at 160% of full
scale; downrange occurs at 15% of full scale

Enables manual selection of fiied ranges. Ranges permissible for
each function are inscribed on the parlel

,Enables the print pulse causing BCD data at P201 to be recorded

by printer, or other output device. (Output data is present at
P201 regardless of the position of this switch.)

PROGRAM CONTROL
(pushbutton)

Depressed

Enables the selection of range, function, and mode to be made
externally through the remote programming connector and dis.
ables all front panel controls (requires programming option)

RATIO
(pushbutton)

Depressed

Selects a ratio measurement in which the readout represents the
ratio of the input to an external d-c reference voltage (applied at

terminals on the rear panel) multiplied by 10: Ein/ERafx 10

FILTER

Depressed

Adds an active four.pole filter across the input circuit

(pushbutton)

RATE EXT (ccw)

(pot)

cw

FRONT/REAR FRONT

Selects the Hold mode. A new reading is initiated through the
remote program input

Increase periodic read rate to a maximum of four readings/second

Connects front panel data input terminals to instrument

(slide switch)

REAR

Connects rear panel data input terminals to instrument

*NOTE: Ohms input terminals are open in AC or DC function.

TNOTE: For inputs greater than lSOV, Filter should be “IN”.

980453

2.23 MEASUREMENT CONNECTIONS.

NOTE

Before taking any measurements, refer, to the list of
maximum input voltages, table 2.2.

Table 2.2 - hlaximum Input Voltage

CAUTION

Do not exceed the following maximum inputs:

DC

AC

1lOOVDCor 1OOOVRMSAC

1OOOV RMS decreasihg to 20V RMS at

1 MHz (see figure 2.7)

n

+SOOV peak between +I and -I(lOOOV
RMS if in DC or AC function.)

RATIO

Input: same as function selected

Reference: +lO.SV, -0.5V

achieved by ‘placing a shorting bar between - INPUT and
GUARD and shorting the single banana plug (shield) to the

-

INPUT side of the double banana plug at the input con­nector. This arrangement is adequate for measuring all but
low voltage (mV) levels and/or in high-noise environments.

2.27 When making “floating”voltage measurements(both
measurement points above ground potential), do not con­nect GUARD to measurement ground without making sure
that the voltage between GUARD and - INPUT does not
exceed 250 volts.

Y

‘RMS

GUARD

Voltage between GUARD and - INPUl
must not exceed 250 volts or damage
to the instrument may result

2.24 Basic Voltage Measurement.

2.25 An ac or dc voltage measurement connection rec­ommended to minimize the effects of noise requires a two­conductor shielded cable connected as shown in figure 2.6.

t

Figure 2.6. Basic Voltage Measurement Connections

2.26 For all voltage measurements, the GUARD lead ar

Id
the - INPUT lead are connected to the measurement point
nearest ground potential.

Somewhat less shielding is

2.28 Ohms Measurement.

2.29

Ohms measurement in the Model 5900 consists of
the application of a known current through the unknown
resistance (Rx) and measuring the ratio of the voltage drop
across Rx to the drop across an internal “full-scale” resistor
(Eh/EFS). Current through Rx is applied through leads
from the f. OHMS CURRENT terminals. The voltage drop

is sensed by the + INPUT terminals.

2.30 TWO.WIRE MEASUREMENTS.

2.31

Connections for a simple two-wire shielded ohms

measurement are shown in figure 2.8a. It consists simply of
a single-conductor shielded cable with the conductor serving
as both the t CURRENT and + INPUT leads and the shield

2.4

(4

(b)

Y&v453

lNP”T CVRRENT

Figure 2.8 - Two Wire Ohms Measurements

RX

2-s

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2-6

Figure 2.9 - Four Wire Ohms Measurement

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carrying - CURRENT and - INPUT. While reasonably
accurate measurements can be made with this method,

shunt leakage problems result from the parallel combinations

of Rx and the cable impedance. This causes loss of accuracy,
especially at high resistance (100 Ma range). Also, lead
resistance becomes a factor in the 10 and 100 ohms ranges;

the four wire measurement system is recommended for

these ranges.

2.32 A more accurate two-wire measurement connection

is shown in figure 2.6b. The + INPUT and + CURRENT,

-

INPUT and - CURRENT terminals are again tied to-

gether. But now, the positive side is a single-conductor,

shielded cable with the shield tied to Ohms Guard. Ohms

Guard is the low ANALOG OUTPUT terminal on the rear

panel of the Model 5900 when ohms is selected. The negative
side is a single wire connected as shown. Guard current is
present in the low side, but the leakage problems of the
first configuration are eliminated.

2.33 In high noise-level environments, the configuration
shown in figure 2.8~ is recommended. This method also

eliminates error due to shunt leakage, but provides more

complete shielding. The positive terminals are tied together
and carried in a single-conductor, double-shielded cable with

the inner shield tied to OhmsGuard (-ANALOG OUTPUT).

The outer shield is tied to GUARD. The negative terminals

are tied together and carried in a single-conductor shielded
cable with the shield tied to GUARD. This configuration
eliminates guard current sensitivity, thereby increasing
guarding characteristics.

2.36 This configuration, although shielded, places the
shield capacitance and cable leakage in parallel with Rx.

This results in loss of accuracy and slow measurements. In

addition, it is very responsive to the triboelectric effect at
high resistance measurements.

2.39 Better guarding is achieved by the use of the con­figuration shown in figure 2.9b. Here again, RG196U teflon
dielectric cable (either single-conductor shielded or two­conductor shielded) is used on the positive terminals. The
shield(s) are connected to Ohms Guard (low ANALOG
OUTPUT terminal). The negative leads are single wires with
the - INPUT terminal tied to GUARD.

2.40 This eliminates much of the shunt leakage problem

of the previous configuration since guard current now flows

through the low side of the measurement circuit. Measure­ment is much faster since the shield capacity is driven by
the guard current.

2.41 A high-noise environment calls for the “super”
configuration shown in figure 2.9~. Here, a two-conductor,
double-shielded cable is used as the positive leads. The inner
shield is tied to Ohms Guard. A twoanductor shielded
cable is used as the negative leads. Its shield is tied to
GUARD and to the outer shield of the positive cable. The

shield is also tied to CURRENT at the measurement point.
This configuration maintains high guarding characteristics
while eliminating guard current sensitivity.

2.42 Ratio Measurements.

2.34 FOUR-WIRE MEASUREMENTS

2.35 In most system applications, the device to be meas­ured is located at B remote location requiring interconnection
by cables of lengths from several to possibly hundreds of
feet. When measuring low resistance values over long cables,
most lead resistance problems can be solved by the use of a
four-wire measurement system.

2.36 For high resistance measurements over long cables,
other problems are encountered: noise pick-up, leakage
resistance, and capacitive loading of the system. These
problems can be minimized by proper shielding and the use
of ohms guard.

2.37 Figure 2.9a shows a basic shielded four-wire ohms
measurement configuration. This method uses two single­conductor shielded teflon cables. The conductors carry the
positive sides of the INPUT and CURRENT lines while each
shield carries the low side.

2.43 Ratio measurements are made by applying a positive

d-c voltage to the reference input terminals on the rear panel

and an input signal of any function at the front input
terminals. For DC/DC or AC/DC ratios, the reference

voltage must be within the range of +IV to +lO.SV. Input

signal limitations (numerator) are the same as tbosc given
for conventional measurement of the particular function

(table 2.2). The readout is the ratio multiplied by ten:

Einput/Ereference x 10. In the standard instrument the

INPUT terminal is internally connected to the REF in­put terminal; in instruments equipped with the option 62
4-wire ratio, both reference inputs arc floating (IO Ma
between - REF and -SIGNAL).

2.44 SYSTEM CAPABILITIES.

2.45 The 5900 has two system interface connectorsdesig­nated as 3201 (PRINTER OUTPUT) and 5202 (PROGRAM
INPUT) mounted on the rear panel of the instrument (fig
ure 2.10). The following is a brief description of the capa­bilities of each connector.

2-7

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Printer Output - 5201.

2.46

2.47 Through this connector the 5900 supplies BCD
representations of the decimal display; various flags or
indicators of the mode of operation, function and range;
and a print command. Provision has also been made for 60
Hz instruments to accept a fast (20 readings per second
maximum) or a superfast (I 01 readings per second minimum)
read command. In 50 Hz units, the fast command obtains

I7 readings per second, minimum, and the superfast com-

mand 93 readings per second.

2.48 Program Input.

2.49

Through this connector the 5900 receives externally
generated signals that select the function, range, mode of
operation, and initiate the read commands.

2.50 LOGIC LEVELS AND ELECTRONIC IN-

TERFACE.

TTL-compatible positive-true logic levels are used

2.5 1
in the 5900. In some instances, however, complementary
signals are used. These terms are more specifically defined
below:

other words, the complement of X is x. The truth table
shows that the two signals X and x, are by definition, in
opposite logic states (see table 2.3).

Table 2.3 - Positive True Logic Relationships

Voltage Level of

Voltage Level of

Signal Logic State Output Line “x” Output Line “p

“X” True or “1” 2.4 - 5.0

False or “0” 1 0.0-0.4

2.53

As seen above, if gate A has a true or “1” level on

Volts 0.0.0.4
Volts 1

2.4.5.0

output X, its voltage level is the most positive of the two
ranges present, and output x must be in a false or “0”
state with the lowest or most negative voltage range present.

The reverse would be true for a false or “0” level on output

X.

2.54 Driving the Inputs.

2.55 All inputs are TTL compatible and most are the
equivalent of one 7400 series TTL input with a pull-up
resistor for contact closure operation.

Signals and Their Complements -

2.52

If the non-inverting output of gate A is defined as

signal X, then it follows that the inverting output is ???; in

Figure 2. IO - Rear Panel

0

2.56 TTL Loading Conditions,

2.57 To input a “I” level the pull.up resistor will supply

the necessary source current (40 /.tA) to maintain the mini­mum 2.4 volts. In fact, the pull-up resistor will maintain a

2-8

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Figure 2.11 Measurement Sequence

2-9

980453
one level as long as the input source resistance (RI) to

ground is greater than ISK ohms.

2.58 To input a “0” level, at least 2.0 ma of current must
be sinked maintaining the input voltage below 0.4 volts.
This requires a resistance to ground of 200 ohms or less.

Exceptions to Input Loading Conditions.

2.59
a.

Program Storage Input (5202, pin B.15) is the
equivalent of 3 TTL inputs and requires a minimum

5.8 ma sinking current, or 68 ohms or less to com­mon.

b.

Maximum input voltage level, referenced to common,
must not exceed 5.5 volts peak. Otherwise, gate
destruction will occur.

c.

The Direct and Time Out Commands are AC coupled

with pullap resistors to t5 volts. These inputs are
compatible with TTL outputs or contact closures
to ground. The AC coupling does require that rise
and fall times be less than 100 peconds. This input
circuit is illustrated below:

ts” +5V

P 9

2.62 Timing Sequence.

2.63 The standard remote mode of operation of the 5900
is to initiate a reading sequence with each Direct Command
received through the programmer, providing
time has been allowed between commands for the reading
to be completed. This reading sequence is illustrated in
figure 2. I I

TI .To

T2-TI

T3-T2

T4.T3

During this period the input signal must fin­ish settling to within the desired accuracy.
Any control changes involving the 25 msec
relay settling time (a) can he completed;
other logic control inputs (b) can also be
changed.

The Direct Comma signal, which is AC

coupled, must meet the following conditions:
a. Rise and fall times less than 100 /.wc.
b.

Signal must stay in the logical “0”
state for at least 3.4 /&ec. If these
conditions are met, the internal read
command is sustained at T2 and the
signal integrate period is started.

The period of signal integration lasts for

16.2/3 mw (60 Hz line frequency; 20 mw
in 50 Hz units). During this time the inte­grator charges to a voltage proportional to
the input voltage. This is the input sampling
period.

During this period, the integrator is isolated
from the input signal, and is discharged at a.

precise current. The time the integrator re­quires to discharge to a level equal to its
voltage at T2 is proportional to the input
voltage. This time is measured by an internal
counter and stored.

that

sufficient

d. Digital output common can be floated as high as

200 VDC above power line ground.

2.60. TTL Output Capabilities.

2.61 The 5900 electrical outputs are specified to drive
two ‘ITL inputs such as described in the TTL loading section.
Summary:

False: 0 to tO.4V
True: t2.4 to +S.OV
Fanout: 2minimum ,
Maximum Capacitance Load: 500 pF

2-10

T5.T4

To-TS

TI -To

This I.7 /J.W period is required to strobe the

new reading from the internal counter into
the readout latches.

This 5 mseconds (&IO%) is required to reset

the internal logic for the next reading.

If the next read command is a Direct
Command, this period must be made long
enough to allow for the condition covered in
the first cycle; however, if the next command
is a Timeout Command, this period can
approach zero since the necessary timeout to
satisfy these conditions are automatically
programmed.

980453

Figure 2.12. Command Timing

2.64 Other Read Command Options.

2.65 In addition to the Direct Command, there are two
other programmable read commands, as illustrated in fig­ure 2.12.

a.

Time Out Command: Again, this is an AC coupled

input which must have rise and fall times of less
than 100 weconds but must remain in a “0” state
for at least 0.1 @second. The timeouts given in
table 2.7 for various combinatioris of ranges and
functions ranging from 30 mseconds to 500 msec.
onds will be automatically inserted before the in­ternal read command is generated. If this command

is wired to the m on J2Ol - pin
All, fully automatic reading with timeouts is
achieved.

The 5 msec internal delay is not adequate for settling
time on the 100 VDC, 1000 Ka 10 MS1, IO0 MS1
ranges, or any AC range. Therefore, the timeout com­mand, providing timeout delays listed in table 2.7,
must be used to initiate accurate readings on these
ranges unless a fixed range and function have been
programmed and the input has been present longer
than the timeout period.

System Direct Command: While the other two read

b.

commands were AC coupled and programmed

through the Program Input Connector (J202), this
command is DC coupled and programmed through

2-11

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Figure 2.13. Minimum Read Rate vs. Input

the Printer Output Connector (5201). The $&%
Direct Command must remain in the “0” state for
at least 3.4 /.&seconds to generate the internal read
command. This delay, as in the Direct Command, is and internal reset remain fixed while the reference integrate
to prevent noise from triggering the readings. If this period can vary from 0 to 32 mseconds. Therefore the
command is tied to ground, the 5900 will recycle at maximum read rate could very from 17.4 to 45 reading per
its maximum reading rate with no timeouts. second.

2.66 Reading Rates.

2.67 In figure 2.13, integrator operation with three dif­ferent input signal levels is illustrated: half scale, full scale,

2-12

and 160% of full scale (full scale is defined as 100000 on any
range). The figure shows that the maximum reading rate is
a function of the input signal. The signal integrate period

2.66 Superfast.

2.69 The Superfast reading mode (programmed through

either the PRINTER OUT or PROGRAM INPUT connector)

980453

Figure 2.14

- Superfast

increases the minimum reading rate from 20.5 to 102
readings per second (50 Hz: 17.4 to 93 r/s). This is done at
the expense of losing the least-significant digit which is re­set to zero (blanked out on readout). The signal integration
period is reduced from 16.2/3 msec to I -2/3 msec (SO Hz:

20

msec to 2 msec). This and the resulting reference inte­grate period reduce the maximum recycle time from 48.8
msec to 9.8 msec (SO Hz: 57.5 msec to 10.7 msec), thereby
yielding the 107 reading per second figure (93 r/s with 50
Hz). Timing changes are shown in figure 2.14.

2.70 PRINTER OUTPUT.

2.71 The printer output connector is a double-edged

PCB connector (extension of Interconnection and Logic

board) with pins Al through A22 on the bottom edge and

pins B I through B22 on the top edge. Pin assignments are
shown in figure 2.15. All outputs are referenced to digital
ground pin B I.

Read Rate (Worst Case)

2.72 Numerical Data

2.73 Numerical data appears as positive true, four-line
BCD code, as shown in figure 2.15. The designator of each
line identifies the digit and weight. For example: Pins Al8,

19, 20, and 21 are designated 12. Ig, 14. and I, consecu­tively. The 1 indicates these lines correspond to the units
or least significant display; the 2, 8, 4, and I subscripts
indicate the hinary weight of each line.

CAUTION

True output lines arc not short-circuit proof. Acci­dental grounding may damage the output circuitry.

2.13