Tektronix 2520 User Manual

www.tek.com/keithley

Model 2520 Pulsed Laser Diode
Test System

User's Manual

2520-900-01 Rev. D / January 2020

*P2520-900-01D*

2520-900-01D

Model 2520 Pulsed Laser

Diode Test System

User’s Manual

© 2019, Keithley Instruments, LLC

Cleveland, Ohio, U.S.A.

All rights reserved.

Any unauthorized reproduction, photocopy, or use of the information herein, in whole or in part,

without the prior written approval of Keithley Instruments, LLC, is strictly prohibited.

These are the original instructions in English.

All Keithley Instruments product names are trademarks or registered trademarks of Keithley

Instruments, LLC. Other brand names are trademarks or registered trademarks of their respective

holders.

The Lua 5.0 software and associated documentation files are copyright © 1994 - 2015, Lua.org,

PUC-Rio. You can access terms of license for the Lua software and associated documentation at the

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Document number: 2520-900-01 Rev. D / January 2020

).

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 nonhazardous voltages, there are situations where hazardous
conditions may be present.

This product is intended for use by personnel who recognize shock hazards and are familiar with the safety precautions required to
avoid possible injury. Read and follow all installation, operation, and maintenance information carefully before using the product.
Refer to the user documentation for complete product specifications.

If the product is used in a manner not specified, the protection provided by the product warranty may be impaired.

The types of product users are:

Responsible body is the individual or group responsible for the use and maintenance of equipment, for ensuring that the
equipment is operated within its specifications and operating limits, and for ensuring that operators are adequately trained.

Operators use the product for its intended function. They must be trained in electrical safety procedures and proper use of the
instrument. They must be protected from electric shock and contact with hazardous live circuits.

Maintenance personnel perform routine procedures on the product to keep it operating properly, for example, setting the line
voltage or replacing consumable materials. Maintenance procedures are described in the user documentation. 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, perform safe installations, and repair products. Only properly trained service
personnel may perform installation and service procedures.

Keithley products are designed for use with electrical signals that are measurement, control, and data I/O connections, with low
transient overvoltages, and must not be directly connected to mains voltage or to voltage sources with high transient overvoltages.
Measurement Category II (as referenced in IEC 60664) connections require protection for high transient overvoltages often
associated with local AC mains connections. Certain Keithley measuring instruments may be connected to mains. These
instruments will be marked as category II or higher.

Unless explicitly allowed in the specifications, operating manual, and instrument labels, do not connect any instrument to mains.

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 30 V RMS,

42.4 V peak, or 60 VDC are present. A good safety practice is to expect that hazardous voltage is present in any unknown circuit
before measuring.

Operators of this product must be protected from electric shock at all times. The responsible body must ensure that operators are
prevented access and/or insulated from every connection point. In some cases, connections must be exposed to potential human
contact. Product operators in these circumstances must be trained to protect themselves from the risk of electric shock. If the circuit
is capable of operating at or above 1000 V, no conductive part of the circuit may be exposed.

Do not connect switching cards directly to unlimited power circuits. They are intended to be used with impedance-limited sources.
NEVER connect switching cards directly to AC mains. When connecting sources to switching cards, install protective devices to
limit fault current and voltage to the card.

Before operating an instrument, ensure that the line cord is connected to a properly-grounded power receptacle. Inspect the
connecting cables, test leads, and jumpers for possible wear, cracks, or breaks before each use.

When installing equipment where access to the main power cord is restricted, such as rack mounting, a separate main input power
disconnect device must be provided in close proximity to the equipment and within easy reach of the operator.

For maximum safety, do not touch the product, test cables, or any other instruments while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge any capacitors before: connecting or disconnecting 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.

For safety, instruments and accessories must be used in accordance with the operating instructions. If the instruments or
accessories are used in a manner not specified in the operating instructions, the protection provided by the equipment may be
impaired.

Do not exceed the maximum signal levels of the instruments and accessories. Maximum signal levels are defined in the
specifications and operating information and shown on the instrument panels, test fixture panels, and switching cards.

When fuses are used in a product, replace with the same type and rating for continued protection against fire hazard.

Chassis connections must only be used as shield connections for measuring circuits, NOT as protective earth (safety 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 protective earth (safety ground) using the wire recommended in the user documentation.

The symbol on an instrument means caution, risk of hazard. The user must refer to the operating instructions located in the
user documentation in all cases where the symbol is marked on the instrument.

The symbol on an instrument means warning, risk of electric shock. Use standard safety precautions to avoid personal
contact with these voltages.

The symbol on an instrument shows that the surface may be hot. Avoid personal contact to prevent burns.

The symbol indicates a connection terminal to the equipment frame.

If this symbol is on a product, it indicates that mercury is present in the display lamp. Please note that the lamp must be
properly disposed of according to federal, state, and local laws.

The WARNING heading in the user documentation explains hazards that might result in personal injury or death. Always read the
associated information very carefully before performing the indicated procedure.

The CAUTION heading in the user documentation explains hazards that could damage the instrument. Such damage may
invalidate the warranty.

The CAUTION heading with the symbol in the user documentation explains hazards that could result in moderate or minor
injury or damage the instrument. Always read the associated information very carefully before performing the indicated procedure.
Damage to the instrument may invalidate the warranty.

Instrumentation and accessories shall not be connected to humans.

Before performing any maintenance, disconnect the line cord and all test cables.

To maintain protection from electric shock and fire, replacement components in mains circuits — including the power transformer,
test leads, and input jacks — must be purchased from Keithley. Standard fuses with applicable national safety approvals may be
used if the rating and type are the same. The detachable mains power cord provided with the instrument may only be replaced with
a similarly rated power cord. 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 to maintain accuracy
and functionality of the product). If you are unsure about the applicability of a replacement component, call a Keithley office for
information.

Unless otherwise noted in product-specific literature, Keithley instruments are designed to operate indoors only, in the following
environment: Altitude at or below 2,000 m (6,562 ft); temperature 0 °C to 50 °C (32 °F to 122 °F); and pollution degree 1 or 2.

To clean an instrument, use a cloth dampened with deionized water or mild, water-based cleaner. Clean the exterior of the
instrument only. Do not apply cleaner directly to the instrument or allow liquids to enter or spill on the instrument. Products that
consist of a circuit board with no case or chassis (e.g., a data acquisition board for installation into a computer) should never require
cleaning if handled according to instructions. If the board becomes contaminated and operation is affected, the board should be
returned to the factory for proper cleaning/servicing.

Safety precaution revision as of June 2017.

Table of Contents

1 Getting Started

General information ................................................................... 1-2

Warranty information .......................................................... 1-2

Contact information ............................................................ 1-2

Specifications ...................................................................... 1-2

Safety symbols and terms ................................................... 1-2

Inspection ............................................................................ 1-3

Options and accessories ...................................................... 1-3

Product overview ........................................................................ 1-5

Mainframe front and rear panel familiarization ......................... 1-6

Front panel summary .......................................................... 1-6

Rear panel summary ........................................................... 1-7

Testhead front and rear panel familiarization ............................. 1-9

Front panel summary .......................................................... 1-9

Rear panel summary ......................................................... 1-10

Power-up .................................................................................. 1-11

Line voltage ...................................................................... 1-11

Line power connection ...................................................... 1-11

Power-up sequence ........................................................... 1-11

System identification ......................................................... 1-12

Fuse replacement .............................................................. 1-12

Display ..................................................................................... 1-13

Display format .................................................................. 1-13

Status and error messages ................................................. 1-13

Remote display programming ........................................... 1-14

Front panel display tests .................................................... 1-14

Default settings ......................................................................... 1-14

Saving and restoring user setups ....................................... 1-14

Power-on configuration ..................................................... 1-15

Factory default settings ..................................................... 1-15

Remote setups ................................................................... 1-17

Menus ....................................................................................... 1-17

Main menu ........................................................................ 1-18

Rules to navigate menus ................................................... 1-18

Main operation menus ....................................................... 1-19

Configuration menus ......................................................... 1-21

Signal cables and adapters ........................................... 1-3

Interface cables ............................................................ 1-4

Rack mount kits ........................................................... 1-4

Display example ........................................................ 1-13

Display units .............................................................. 1-13

Saving setups ............................................................. 1-14

Restoring setups ......................................................... 1-15

2

Connections

Connection precautions

Testhead preparation ................................................................... 2-3

Testhead mounting .............................................................. 2-3

Testhead connections ........................................................... 2-3

Signal connectors ........................................................................ 2-5

Signal connectors ................................................................ 2-5

Triax DETECTOR connectors ............................................ 2-6

CURRENT OUTPUT and VOLTAGE SENSE

connectors ...................................................................... 2-6

Interlock connections .................................................................. 2-6

Remote interlock connections ............................................. 2-6

Key interlock ....................................................................... 2-7

Laser diode test connections ....................................................... 2-7

Connecting cables ............................................................... 2-7

Typical connections ............................................................. 2-7

Equivalent circuit ................................................................. 2-8

Polarity considerations ........................................................ 2-8

Connection considerations ................................................ 2-10

.............................................................. 2-2

3

Basic Operation

Operation o

Configuring sources .................................................................... 3-9

Configuring measurements ....................................................... 3-12

Remote source and measure configuration ............................... 3-13

verview .................................................................... 3-2

Laser diode source and measure capabilities ...................... 3-2

Laser diode source and measure ranges ....................... 3-2

Laser diode source compliance .................................... 3-3

Photodiode source and measure capabilities ....................... 3-3

Photodiode source and measure ranges ........................ 3-4

Basic circuit configuration .................................................. 3-5

Polarity ................................................................................ 3-6

Laser diode current source polarity .............................. 3-6

Laser diode voltage measurement polarity .................. 3-7

Detector measurement polarity .................................... 3-8

Voltage bias polarity ..................................................... 3-8

Editing source values ........................................................... 3-9

Configuring laser diode source .......................................... 3-10

DC mode .................................................................... 3-10

Pulse mode ................................................................. 3-11

Setting photodiode detector source values ........................ 3-11

Configuring laser diode measurements ............................. 3-12

Configuring photodiode measurements ............................. 3-12

Source and measure configuration commands .................. 3-13

Programming example ............................................... 3-14

4

Laser Diode Testing

Source and measure configuration menus

Front panel laser diode testing ................................................... 4-3

Test circuit configuration .................................................... 4-3

Front panel test procedure ................................................... 4-4

Step 1: Configure laser diode measurement

function .................................................................. 4-4

Step 2: Configure photodiode detector measurement

functions ................................................................. 4-4

Step 3: Configure laser diode current source ............... 4-4

Step 4: Configure photodiode detector voltage bias

sources .................................................................... 4-4

Step 5: Configure math functions ................................ 4-5

Step 6: Turn source outputs on and trigger readings ... 4-5

Step 7: Observe readings on the display ...................... 4-5

Step 8: Turn source outputs off .................................... 4-5

Remote laser diode testing ......................................................... 4-5

Laser diode test commands ................................................. 4-5

Programming example ................................................. 4-7

.................................. 4-2

5

Source-Measure Concepts

Pulse concepts

Overview ............................................................................. 5-2

Delay-pulse cycle ................................................................ 5-2

Front panel pulse parameters .............................................. 5-4

Remote pulse parameters .................................................... 5-6

Pulse rise and fall times ...................................................... 5-7

Sweep waveforms ...................................................................... 5-8

Staircase sweeps .................................................................. 5-8

Custom sweep ..................................................................... 5-8

Current source operating boundaries ....................................... 5-10

Limit lines ......................................................................... 5-10

Loading effects .................................................................. 5-10

Data flow .................................................................................. 5-12

Basic reading display ........................................................ 5-12

Math function display ....................................................... 5-12

Sweep data storage ............................................................ 5-12

............................................................................ 5-2

Delay phase .................................................................. 5-3

Pulse phase ................................................................... 5-3

Duty cycle .................................................................... 5-3

Fixed mode .................................................................. 5-4

Staircase sweep mode .................................................. 5-4

Fixed mode .................................................................. 5-6

Staircase sweep mode .................................................. 5-6

6

Range, Filter, and Math

Range ..........................................................................................

Measurement ranges ............................................................ 6-2

Laser diode voltage ranges ........................................... 6-2

Photodiode detector current ranges .............................. 6-2

Maximum readings ...................................................... 6-3

Setting the measurement range .................................... 6-3

Source ranging ..................................................................... 6-3

Remote range programming ................................................ 6-3

Range programming example ...................................... 6-4

Filter ........................................................................................... 6-4

Averaging filter overview .................................................... 6-4

Filter configuration .............................................................. 6-5

Filter control ........................................................................ 6-5

Remote filter programming ................................................. 6-5

Filter command ............................................................ 6-5

Filter programming example ........................................ 6-6

Measurement math functions ..................................................... 6-6

Conductance ........................................................................ 6-7

Resistance ............................................................................ 6-7

Power ................................................................................... 6-7

MX + B ................................................................................ 6-7

Delta (remote only) ............................................................. 6-7

Front panel math functions .................................................. 6-8

Math configuration menu ............................................. 6-8

Programming math functions ....................................... 6-8

Remote math functions ........................................................ 6-9

Math function commands ............................................. 6-9

Math function programming example ........................ 6-10

6-2

7

Sweep Operation

Sweep types

Linear staircase sweep ......................................................... 7-2

Logarithmic staircase sweep ............................................... 7-3

Custom sweep ..................................................................... 7-4

Configuring and running a sweep ............................................... 7-5

Front panel sweep operation ............................................... 7-5

Performing sweeps .............................................................. 7-6

Remote sweep operation ..................................................... 7-8

................................................................................ 7-2

Configuring a sweep ..................................................... 7-5

Performing a linear staircase sweep ............................. 7-6

Performing a log staircase sweep ................................. 7-7

Staircase sweep commands .......................................... 7-8

Staircase sweep programming example ....................... 7-9

Custom sweep commands .......................................... 7-10

Custom sweep programming example ....................... 7-10

8 Triggering

Trigger model (front panel operation) ........................................ 8-2

Idle layer ............................................................................. 8-3

Input triggers ....................................................................... 8-3

Delay and pulse phases ....................................................... 8-3

Delay phase .................................................................. 8-3

Pulse phase ................................................................... 8-4

Filtering ........................................................................ 8-4

Sweep points ................................................................ 8-4

Counter ................................................................................ 8-4

Output trigger ...................................................................... 8-4

Bench defaults ..................................................................... 8-5

Operation summary ............................................................. 8-5

Trigger link ................................................................................. 8-5

Input trigger requirements ................................................... 8-6

Output trigger specifications ............................................... 8-6

Configuring triggering ................................................................ 8-7

CONFIGURE TRIGGER menu ......................................... 8-7

Remote triggering ...................................................................... 8-9

Trigger model (remote operation) ....................................... 8-9

Idle and initiate ................................................................... 8-9

Event detection .................................................................. 8-11

Input triggers ..................................................................... 8-11

Delay and pulse phases ..................................................... 8-12

Delay phase ................................................................ 8-12

Pulse phase ................................................................. 8-12

Filtering ...................................................................... 8-12

Sweep points .............................................................. 8-12

Counter .............................................................................. 8-12

Output trigger .................................................................... 8-13

GPIB defaults .................................................................... 8-13

Operation summary ........................................................... 8-13

Remote trigger commands ................................................ 8-13

Remote trigger example .................................................... 8-14

9 Digital I/O Port, Interlocks, and Pulse Sync Output

Digital I/O port ........................................................................... 9-2

Port configuration ................................................................ 9-2

Digital output lines ...................................................... 9-2

Start-of-test (SOT) line ................................................ 9-3

+5V output ................................................................... 9-3

Digital output configuration ................................................ 9-3

Sink operation .............................................................. 9-3

Source operation .......................................................... 9-4

Controlling digital output lines

Front panel digital output control ................................. 9-4

Remote digital output control ...................................... 9-5

Interlocks .................................................................................... 9-5

Interlock operation .............................................................. 9-6

Interlock status indicator test sequence ............................... 9-7

Reading interlock state ........................................................ 9-7

Pulse sync output ........................................................................ 9-8

Pulse sync waveform ........................................................... 9-8

Pulse sync connections ........................................................ 9-9

........................................... 9-4

10

Remote Operations

Dif

ferences: remote vs. local operation .................................... 10-2

Local-to-remote transition ................................................. 10-2

Remote-to-local transition ................................................. 10-2

Selecting an interface ............................................................... 10-2

GPIB operation ......................................................................... 10-3

GPIB standards .................................................................. 10-3

GPIB connections .............................................................. 10-4

Primary address ................................................................. 10-6

General bus commands ............................................................. 10-6

REN (remote enable) ......................................................... 10-7

IFC (interface clear) .......................................................... 10-7

LLO (local lockout) ........................................................... 10-7

GTL (go to local) ............................................................... 10-7

DCL (device clear) ............................................................ 10-7

SDC (selective device clear) .............................................. 10-8

GET (group execute trigger) ............................................. 10-8

SPE, SPD (serial polling) .................................................. 10-8

Front panel GPIB operation ...................................................... 10-8

Error and status messages ................................................. 10-8

GPIB status indicators ....................................................... 10-9

REM ........................................................................... 10-9

TALK ......................................................................... 10-9

LSTN .......................................................................... 10-9

SRQ ............................................................................ 10-9

LOCAL key ....................................................................... 10-9

Programming syntax ............................................................... 10-10

Command words ............................................................. 10-10

Commands and command parameters ..................... 10-10

Query commands ............................................................. 10-12

Case sensitivity ................................................................ 10-12

Long-form and short-form versions ................................ 10-12

Short-form rules .............................................................. 10-13

Program messages

Single command messages ...................................... 10-13

Multiple command messages ................................... 10-14

Command path rules ................................................ 10-14

Using common and SCPI commands in the same

message .............................................................. 10-15

Program message terminator (PMT) ....................... 10-15

Command execution rules ....................................... 10-15

Response messages ......................................................... 10-15

Sending a response message .................................... 10-15

Multiple response messages .................................... 10-15

Response message terminator (RMT) ..................... 10-16

Message exchange protocol ............................................ 10-16

RS-232 interface operation .................................................... 10-16

Sending and receiving data ............................................. 10-16

Baud rate ......................................................................... 10-16

Data bits and parity ......................................................... 10-17

Terminator ....................................................................... 10-17

Flow control (signal handshaking) .................................. 10-17

RS-232 connections ........................................................ 10-18

Error messages ................................................................ 10-20

Programming example .................................................... 10-20

1 Status Structure

1

Ov

erview .................................................................................. 11-2

Status byte and SRQ ......................................................... 11-2

Status register sets ............................................................. 11-2

Queues ............................................................................... 11-2

Clearing registers and queues ................................................... 11-4

Programming and reading registers ......................................... 11-5

Programming enable registers ........................................... 11-5

Reading registers ............................................................... 11-6

Status byte and service request (SRQ) ..................................... 11-7

Status byte register ............................................................ 11-8

Service request enable register .......................................... 11-8

Serial polling and SRQ ..................................................... 11-9

SPE, SPD (serial polling) .......................................... 11-9

Status byte and service request commands ..................... 11-10

Programming example - set MSS (B6) when

error occurs ........................................................ 11-10

Status register sets .................................................................. 11-11

Register bit descriptions .................................................. 11-11

Standard event register ............................................. 11-11

Operation event register ........................................... 11-13

Measurement event register ..................................... 11-14

Questionable event register ...................................... 11-16

........................................................... 10-13

Condition re

Event registers ................................................................. 11-17

Event enable registers ...................................................... 11-18

Programming example - program and read

Queues .................................................................................... 11-19

Output queue ................................................................... 11-19

Error queue ...................................................................... 11-20

Programming example - read error queue ................ 11-21

gisters .......................................................... 11-17

register set ........................................................... 11-19

12

13

Common Commands

Command summary

Command reference .................................................................. 12-3

*IDN? — identification query............................................ 12-3

*OPC — operation complete ............................................. 12-3

*OPC? — operation complete query ................................. 12-3

*OPC programming example ..................................... 12-4

*OPT? — option query ...................................................... 12-4

*SAV <NRf> — save ......................................................... 12-4

*RCL <NRf> — recall....................................................... 12-4

*SAV, *RCL programming example .......................... 12-5

*RST — reset ..................................................................... 12-5

*TRG — trigger ................................................................. 12-5

*TRG programming example .................................... 12-5

*TST? — self-test query .................................................... 12-6

*WAI — wait-to-continue .................................................. 12-6

.................................................................. 12-2

SCPI Signal-Oriented Measurement Commands

Command summary

Acquiring readings ................................................................... 13-2

FETCh? ............................................................................. 13-2

[:SENSe[1]]:DATA[:LATest]? ........................................... 13-3

[:SENSe2]:DATA[:LATest]? ............................................. 13-3

[:SENSe3]:DATA[:LATest]? ............................................. 13-3

READ? .............................................................................. 13-3

MEASure? ......................................................................... 13-3

.................................................................. 13-2

14

SCPI Command Reference

Reference tables

Calculate subsystems .............................................................. 14-14

Select laser diode math function ..................................... 14-15

FORMat <name> ..................................................... 14-15

Set MX + B parameters ................................................... 14-15

MBFactor <n> .......................................................... 14-15

MMFactor <n> ......................................................... 14-15

UNITs <name> ........................................................ 14-16

........................................................................ 14-2

Enable and read math function result

STATe <b> ............................................................... 14-16

DATA? ..................................................................... 14-17

LATest? .................................................................... 14-17

DISPlay subsystem ................................................................ 14-17

Control display ................................................................ 14-17

ENABle <b> ............................................................ 14-17

ATTRibutes? ............................................................ 14-18

Read display .................................................................... 14-18

DATA? ..................................................................... 14-18

Define :TEXT messages ................................................. 14-18

DATA <a> ................................................................ 14-18

STATe <b> ............................................................... 14-19

FORMat subsystem ................................................................ 14-19

Data format ..................................................................... 14-19

[:DATA] <type>[,length] ......................................... 14-19

Data elements .................................................................. 14-22

ELEMents <item list> ............................................. 14-22

Calculate data elements ................................................... 14-23

CALCulate <item list> ............................................ 14-23

TRACe data elements ..................................................... 14-24

TRACe <item list> ................................................... 14-24

SOURce4 <name> ................................................... 14-25

Byte order ........................................................................ 14-25

BORDer <name> ..................................................... 14-25

Status register format ...................................................... 14-26

SREGister <name> .................................................. 14-26

OUTPut subsystem ................................................................ 14-27

Turn sources on or off ..................................................... 14-27

[:STATe] <b> ........................................................... 14-27

Interlock status ................................................................ 14-27

TRIPped? ................................................................. 14-27

SENSe subsystem .................................................................. 14-27

Select laser diode voltage measurement range ............... 14-28

[:UPPer] <n> ............................................................ 14-28

Select detector current measurement range .................... 14-28

[:UPPer] <n> ............................................................ 14-28

Select polarity ................................................................. 14-29

POLarity <name> .................................................... 14-29

Query voltage limit ......................................................... 14-29

TRIPped? ................................................................. 14-29

Query latest readings ....................................................... 14-30

[:LATest]? ................................................................ 14-30

Configure and control filter ............................................. 14-30

COUNt <n> ............................................................. 14-30

[:STATe] <b> ........................................................... 14-31

.............................. 14-16

Abort sweep

:CABort[:LEVel] <n> .............................................. 14-31

:CABort:STATe <b> ................................................. 14-31

SOURce subsystem ................................................................ 14-32

SOURce[1] ...................................................................... 14-32

Control source outputs on-off .......................................... 14-32

[:IMMediate] ............................................................ 14-32

Select sourcing mode ...................................................... 14-32

MODE <name> ........................................................ 14-32

Select source function ..................................................... 14-33

FUNCtion[:SHAPe] <name> ................................... 14-33

Select source range .......................................................... 14-33

RANGe <n> ............................................................. 14-33

Set amplitudes ................................................................. 14-34

[:IMMediate][:AMPLitude] <n> .............................. 14-34

LOW <n> ................................................................. 14-34

Set voltage limit ............................................................... 14-35

PROTection[:LEVel] <NRf> .................................... 14-35

Select source polarity ...................................................... 14-35

POLarity <name> ..................................................... 14-35

Set pulse times ................................................................. 14-36

DELay <n> ............................................................... 14-36

WIDTh <n> .............................................................. 14-36

TRANsition[:STATe] <b> ........................................ 14-36

Configure sweeps ............................................................ 14-37

SPACing <name> ..................................................... 14-37

STARt <n> ............................................................... 14-37

STOP <n> ................................................................ 14-37

CENTer <n> ............................................................. 14-38

SPAN <n> ................................................................ 14-38

STEP <n> ................................................................. 14-39

POINts <n> .............................................................. 14-40

DIRection <name> ................................................... 14-40

Configure list ................................................................... 14-41

CURRent <NRf list> ................................................ 14-41

APPend <NRf list> .................................................. 14-41

POINts? .................................................................... 14-42

WIDTh <NRf list> ................................................... 14-42

APPend <NRf list> .................................................. 14-42

POINts? .................................................................... 14-42

DELay <NRf list> .................................................... 14-43

APPend <NRf list> .................................................. 14-43

POINts? .................................................................... 14-43

..................................................................... 14-31

Sweep and list program e

Linear staircase sweep ............................................. 14-44

List sweep ................................................................ 14-44

Logarithmic staircase sweep .................................... 14-45

SOURce2 and SOURce3 ................................................ 14-46

Set amplitudes ................................................................. 14-47

[:IMMediate][:AMPLitude] <n> ............................. 14-47

SOURce4 ........................................................................ 14-47

Setting digital output ....................................................... 14-47

[:LEVel] <NRf> | <NDN> ....................................... 14-47

Setting bit size ................................................................. 14-48

BSIZe <n> ............................................................... 14-48

STATus subsystem ................................................................. 14-49

Read event registers ........................................................ 14-49

[:EVENt]? ................................................................ 14-49

Program event enable registers ....................................... 14-49

ENABle <NDN> or <NRf> ..................................... 14-49

Read condition registers .................................................. 14-50

CONDition? ............................................................. 14-50

Select default conditions ................................................. 14-50

PRESet ..................................................................... 14-50

Error queue ...................................................................... 14-50

[:NEXT]? ................................................................. 14-50

CLEar ....................................................................... 14-50

ENABle <list> ......................................................... 14-51

DISable <list> .......................................................... 14-51

SYSTem subsystem ................................................................ 14-51

Default conditions ........................................................... 14-51

PRESet ..................................................................... 14-51

POSetup ................................................................... 14-52

Error queue ...................................................................... 14-52

[:NEXT]? ................................................................. 14-52

ALL? ........................................................................ 14-52

COUNt? ................................................................... 14-53

CODE[:NEXT]? ...................................................... 14-53

CODE:ALL? ............................................................ 14-53

CLEar ....................................................................... 14-53

Simulate key presses ....................................................... 14-53

KEY ......................................................................... 14-53

Read version of SCPI standard ....................................... 14-54

VERSion? ................................................................ 14-54

RS-232 interface ............................................................. 14-55

LOCal ...................................................................... 14-55

REMote .................................................................... 14-55

RWLock ................................................................... 14-55

xamples ................................... 14-44

Reset timestamp

RESet ....................................................................... 14-55

TRACe subsystem .................................................................. 14-56

Read sample buffer .......................................................... 14-56

DATA? ...................................................................... 14-56

VALue? [<NRf>] ..................................................... 14-56

Configure sample buffer .................................................. 14-57

POINts <n> .............................................................. 14-57

Trigger subsystem ................................................................... 14-57

Initiate source/measure cycle .......................................... 14-57

INITiate .................................................................... 14-57

Abort source/measure cycle ............................................ 14-58

ABORt ..................................................................... 14-58

Program trigger model .................................................... 14-58

COUNt <n> .............................................................. 14-58

SOURce <name> ..................................................... 14-58

TIMer <n> ................................................................ 14-59

ILINe <NRf> ............................................................ 14-60

OLINe <NRf> .......................................................... 14-60

OUTPut <name> ...................................................... 14-60

.............................................................. 14-55

A

Specifications

B Status and Error Messages

Introduction ...............................................................................

Status and error messages .......................................................... B-2

Eliminating common SCPI errors ............................................. B-7

-113, "Undefined header" ................................................... B-7

-410, "Query INTERRUPTED" ......................................... B-7

-420, "Query UNTERMINATED" ..................................... B-8

C

Data Flow

Introduction ...............................................................................

Buffers ................................................................................ C-2

SENS1, SENS2, and SENS3 .............................................. C-3

INIT .................................................................................... C-3

FETCh? .............................................................................. C-3

READ? and MEASure? ..................................................... C-4

CALCulate1:DATA?, CALCulate2:DATA?,

CALCulate3:DATA? ..................................................... C-4

CALCulate4:DATA? .......................................................... C-4

TRACe:DATA? and TRACe:DATA:VALue? ..................... C-4

B-2

C-2

D

IEEE-488 Bus Overview

Introduction ...............................................................................

Bus description .......................................................................... D-2

Bus lines .................................................................................... D-5

Data lines ........................................................................... D-5

Bus management lines ....................................................... D-5

Handshake lines ................................................................. D-5

Bus commands .......................................................................... D-7

Uniline commands ............................................................. D-8

Universal multiline commands .......................................... D-8

Addressed multiline commands ......................................... D-9

Address commands ............................................................ D-9

Unaddress commands ........................................................ D-9

Common commands ........................................................ D-10

SCPI commands ............................................................... D-10

Command codes ............................................................... D-10

Typical command sequences ............................................ D-12

IEEE command groups .................................................... D-13

Interface function codes .......................................................... D-14

D-2

E

F

IEEE-488 and SCPI Conformance Information

Introduction ................................................................................

E-2

Measurement Considerations

Optimizing laser diode connections

Current pulse output circuit model ..................................... F-2

Cable inductance ................................................................. F-3

Increasing cable length ....................................................... F-5

Exposed loop area ............................................................... F-6

Sense lead connections ....................................................... F-8

Magnetic coupling ............................................................ F-10

Increasing laser diode pulse measurement speed ..................... F-11

Overview ........................................................................... F-11

Laser diode impedance matching ...................................... F-12

Model 2520 output circuit model ...................................... F-13

Transmission line model ................................................... F-14

Forward voltage measurement .......................................... F-15

Photodiode current measurement channels ....................... F-16

Noise and source impedance .................................................... F-17

DUT resistance .................................................................. F-17

Source capacitance ............................................................ F-18

Generated currents ................................................................... F-18

Offset currents ................................................................... F-19

Dielectric absorption ......................................................... F-19

Voltage burden .......................................................................... F-20

General measurement considerations ....................................... F-20

........................................... F-2

Ground loops

Light ................................................................................. F-21

Electrostatic interference .................................................. F-22

Magnetic fields ................................................................. F-22

Electromagnetic Interference (EMI) ................................ F-23

.................................................................... F-20

G

H

GPIB 488.1 Protocol

Introduction ...............................................................................

Selecting the 488.1 protocol ...................................................... G-2

Protocol differences ................................................................... G-3

Message exchange protocol (MEP) .................................... G-3

Using SCPI-based programs .............................................. G-3

Bus hold-off ........................................................................ G-4

Trigger-on-talk ................................................................... G-4

Message available ............................................................... G-4

General operation notes ...................................................... G-4

Example Programs

Introduction ...............................................................................

Hardware requirements ...................................................... H-2

Software requirements ........................................................ H-2

General program instructions ............................................. H-2

Laser diode test program ........................................................... H-3

Linear staircase sweep program ................................................ H-4

List sweep program ................................................................... H-5

I Continuous Pulse Mode

Continuous pulse mode

Pulse test advantage ............................................................. I-2

Duty cycle ............................................................................ I-2

Configuring the 2520 to use Continuous Pulse Mode ......... I-3

Front panel ................................................................... I-3

Remote configuration over GPIB/IEEE-488 ....................... I-4

Related modes ..................................................................... I-4

.............................................................. I-2

G-2

H-2

1

Getting Started

• General information — Co

mation, contact information, safety symbols and terms, inspection, and available
options and accessories.

• Product overview — Summarizes the features of the Model 2520 Pulsed Laser

Diode Test System.

• Familiarization — Summarizes the controls and connectors on the unit.

• Power-up — Covers line power connection, line voltage settings, fuse replace-

ment, and the power-up sequence.

• Display — Provides information about the Model 2520 display.

• Default settings — Covers factory default setups and saving and recalling user set-

ups.

• Menus — Covers the main and configuration menus as well as rules to navigate

menus.

vers general information that includes warranty infor-

1-2 Getting Started Model 2520 User’s Manual

General information

Extended warranty

Additional years of warranty coverage are available on many products. These valuable
contracts protect you from unbudgeted service expenses and provide additional years of
protection at a fraction of the price of a repair. Extended warranties are available on new
and existing products. Contact your local Keithley Instruments office, sales partner, or
distributor for details.

Contact information

If you have any questions after you review the information in this documentation, please
contact your local Keithley Instruments office, sales partner, or distributor. You can also
call the corporate headquarters of Keithley Instruments (toll-free inside the U.S. and
Canada only) at 1-800-935-5595, or from outside the U.S. at [phone]. For
worldwide contact numbers, visit the Keithley Instruments website (tek.com/keithley).

Specifications

For the most recent specifications, refer to the web site at www.tek.com/keithley.

Safety symbols and terms

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

!

The symbol on an instrument indicates that the user should refer to the operating
instructions located in the manual.

The symbol on the instrument shows that high voltage may be present on the termi­nal(s). Use standard safety precautions to avoid personal contact with these voltages.

The WARNING heading used in this manual explains dangers that might result in per-
sonal 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
instrument. Such damage may invalidate the warranty.

Model 2520 User’s Manual Getting Started

Inspection

The Model 2520 was carefully inspected electrically and mechanically before shipment.
After unpacking all items from the shipping carton, check for any obvious signs of physi­cal damage that may have occurred during transit. (There may be a protective film over the
display lens, which can be removed.) Report any damage to the shipping agent immedi­ately. Save the original packing carton for possible future shipment. The following items
are included with every Model 2520 order:

• Model 2520 mainframe with line cord.

• Model 2520 testhead with two connecting cables.

• Two triax connecting cables for detector signal connections.

• Four unterminated 15Ω BNC coaxial connecting cables for laser diode signal

connections.

• Accessories as ordered.

• Certificate of calibration.

Options and accessories

The following options and accessories are available from Keithley for use with the
Model 2520.

1-3

Signal cables and adapters

CA-289-1A Cable — This 1m low-noise triax cable is terminated at one end with a 3-slot
male triax connector and is unterminated on the other end.

CA-290-1A Cable — This 1m BNC cable is terminated at one end with a male BNC con­nector and is unterminated on the other end.

Model 7078-TRX Triax Cables — These low-noise triax cables are terminated at both
ends with 3-slot male triax connectors. The Model 7078-TRX is available in 0.3m (1ft),

0.9m (3ft), 1.5m (5ft), and 3m (10ft) lengths.

Model 7078-TRX-BNC Adapter — This is a 3-slot male triax to female BNC adapter.
This adapter lets you connect a BNC cable to the triax detector inputs of the Model 2520
testhead.

Model 237-TRX-TBC Connector — This is a 3-lug female triax bulkhead connector
with cap for assembly of custom panels and interface connections.

1-4

Getting Started Model 2520 User’s Manual

Interface cables

Models 7007-1 and 7007-2 shielded GPIB cables — Connect the Model 2520 to the
GPIB b
(EMI). The Model 7007-1 is 1m long; the Model 7007-2 is 2m long.

Model 7009-5 shielded RS-232 cable — Connect the Model 2520 to computer serial port
using shielded cables and connectors to reduce EMI.

Models 8501-1 and 8501-2 trigger link cables — Connect the Model 2520 to other
instruments with Trigger Link connectors (e.g., Model 7001 Switch System). The Model
8501-1 is 1m long; the Model 8501-2 is 2m long.

Model 8502 trigger link adapter — Lets you connect any of the six Trigger Link lines of
the Model 2520 to instruments that use the standard BNC trigger connectors.

Model 8503 DIN to BNC trigger cable — Lets you connect Trigger Link lines one (Volt­meter Complete) and two (External Trigger) of the Model 2520 to instruments that use
BNC trigger connectors. The Model 8503 is 1m long.

us using shielded cables and connectors to reduce Electromagnetic Interference

Rack mount kits

Model 4288-1 single fixed rack mount kit — Mounts a single Model 2520 in a standard
19-inch rack.

Model 4288-2 side-by-side rack mount kit — Mounts tw
428, 486, 487, 2000, 2001, 2002, 2010, 2015, 2016, 2400, 2410, 2420, 2430, 2500, 2510,
2520, 6430, 6517, 7001) side-by-side in a standard 19-inch rack.

Model 4288-3 side-by-side rack mount kit — Mounts a Model 2520 and a Model 199
side-by-side in a standard 19-inch rack.

Model 4288-4 side-by-side rack mount kit — Mounts a Model 2520 and a 5.25-inch
instrument (Models 195A, 196, 220, 224, 230, 263, 595, 614, 617, 705, 740, 775, etc.)
side-by-side in a standard 19-inch rack.

Model 4288-5 dual fixed rack mounting kit — Mounts a Model 2520 and another
3½-inch high instrument (Model 182, 428, 486, 487, 2000, 2010, 2400, 2410, 2420, 2430,
or 7001) side-by-side in a standard 19-inch rack.

o instruments (Models 182,

Model 2520 User’s Manual Getting Started 1-5

Product overview

The Model 2520 Pulsed Laser Diode Test System combines high-current laser diode pulse
and voltage measurement capabilities, and two stable DC bias voltage sources with two
low-noise ammeters for dual-channel photodiode measurements. The unit has 0.3% basic
laser diode voltage measurement accuracy, and 0.3% basic photodiode current measure­ment accuracy. A separate, remote testhead allows versatility for signal connections.

The Model 2520 has the following source and measure capabilities:

• Source DC laser diode current from 10µA to 1A.

• Source laser diode current pulses from 10µA to 5.0A.

• Measure laser diode voltage from 0.33mV to 10.5V.

• Measure photodiode current from 0.7µA to 105mA on each of two channels.

• Source photodiode bias voltage on each of two channels from 0 to ±20V.

Some additional capabilities of the Model 2520 include:

• Sweep capabilities: linear and logarithmic staircase, and custom sweeps for the
laser diode current source.

• Digital I/O port to control other instruments.

• Programming language and remote interfaces — The Model 2520 uses the SCPI
programming language and two remote interface ports (IEEE-488/GPIB and RS­232C).

• Trigger-Link interface to Keithley Series 7000 switching hardware.

• Pulse sync out — Allows synchronizing external instruments with current pulse.

• Math functions — V/I, I/V, power, and MX + B functions.

• Reading and setup storage — Voltage and current readings and seven setups (five
user defaults, factory default, *RST default) can be stored and recalled.

• Closed-cover calibration — The instrument can be calibrated either from the front
panel or remote interface.

1-6

Getting Started Model 2520 User’s Manual

Mainframe front and rear panel familiarization

Front panel summary

The front panel of the Model 2520 mainframe is sho

Figure 1-1

Mainframe front panel

2520 PULSED LASER DIODE TEST SYSTEM

D OUT

DETECTOR 2

VBI

4

TRIG

+/-

CONFIG

PD

5

SWEEP

0000

MENU

EXIT ENTER

I

PD

3

DETECTOR 1

V

B

2

FILTER

89

COMM SETUP

EDIT

MATH

EDIT

LASER

V

L

0

LOCAL

RECALL

67

PW

DELAY

I

L

1

LASER keys:

V

L

I

L

Configure laser diode voltage measure.
Control laser diode current sour

ce.

DETECTOR 1 keys:

V

B

I

PD

Control photodiode detector #1 bias voltage source.
Configure photodiode detector #1 current measure.

wn in Figure 1-1.

RANGE

COMPL

RANGE

ON/OFF

OUTPUT

DETECTOR 2 keys:

V

B

I

PD

Control photodiode detector #2 bias voltage source.
Configure photodiode detector #2 current measure.

EDIT keys:

▲ Increase value.
▼ Decrease value.

▲

▲

Move cursor left.
Move cursor right.

COMPL and RANGE keys:

COMPL Set laser diode source voltage compliance (limit).
RANGE ▲ Increase range.
RANGE ▼ Decrease range.

Model 2520 User’s Manual Getting Started 1-7

Operation keys:

EDIT Enter EDIT mode.
MATH Enable math function.
LOCAL Cancel remote operation.
RECALL Display stored readings and timestamp.
FILTER Control digital filter.
DIG OUT Set Digital I/O port output value.
TRIG Trigger a measurement from the front panel.
SWEEP Start configured sweep.
PW Set laser diode current source pulse width.
DELAY Set laser diode current source pulse delay period.
COMM Select remote interface, set GPIB and RS-232 operating parameters.
SETUP Save/recall default or user instrument setup configurations.
CONFIG Press CONFIG and then appropriate key to configure function or operation.
MENU Access and configure Main Menu selections. When entering numeric data, use to

clear reading to minimum absolute value.
EXIT Cancels selection. Use to back out of menu structures.
ENTER Accepts selection.

Annunciators:

EDIT Instrument in edit mode.
ERR Questionable reading, invalid cal step.
MATH Math function enabled.
REM Instrument in GPIB remote mode.
TALK Instrument addressed to talk over GPIB.
LSTN Instrument addressed to listen over GPIB.
SRQ Service request over GPIB.
FILT Digital filter enabled.
ARM Source-measure operations being performed.
TRIG External trigger source selected.

Output control:

ON/OFF OUTPUT Turns the source outputs on or off.

Handle:

Pull out and rotate to desired position.

Rear panel summary

The rear panel of the Model 2520 mainframe is shown in Figure 1-2.

1-8 Getting Started Model 2520 User’s Manual

WARNING: NO INTERNAL OPERATOR SERVICABLE PARTS, SERVICE BY QUALIFIED PERSONNEL ONLY.

CAUTION: FOR CONTINUED PROTECTION AGAINST FIRE HAZARD, REPLACE FUSE WITH SAME TYPE AND RATING.

Figure 1-2

Mainframe rear panel

MADE IN

U.S.A.

TESTHEAD

CONN 1

!

TESTHEAD

CONN 2

CAT I

PULSE

SYNC

OUT

TRIGGER LINK

!

!

DIGITAL I/O

RS-232

LINE FUSE
SLOWBLOW

1.6A, 250V

LINE RATING

100-240VAC
50, 60Hz
140VA MAX.

IEEE-488

(CHANGE IEEE ADDRESS

WITH FRONT PANEL MENU)

TESTHEAD connectors:

TESTHEAD CONN 1 Connects to testhead MAINFRAME CONN1 connector.
TESTHEAD CONN 2 Connects to testhead MAINFRAME CONN2 connector.

Pulse sync connector:

PULSE SYNC OUT BNC connector provides TTL-compatible pulses synchronized with

laser diode current source pulses.

Trigger link connector:

TRIGGER LINK 8-pin micro-DIN connector for sending and receiving trigger pulses.

Use a trigger link cable or adapter, such as Models 8501-1, 8501-2,
8502, 8504.

Digital input/output port:

DIGITAL I/O Male DB-9 connector for digital output lines, output enable line, and

RS-232 connector:

RS-232 Connector for RS-232 remote operation. Use a straight through (not

GPIB connector:

IEEE-488 Connector for GPIB remote operation. Use a shielded cable (Keithley

Power module:

Contains the AC line receptacle, power on-off switch, and the power line fuse.

start-of-test signal.

null modem) DB-9 cable such as a Keithley Model 7009-5.

Model 7007-1 or 7007-2).

Model 2520 User’s Manual Getting Started 1-9

Testhead front and rear panel familiarization

Front panel summary

The front panel of the Model 2520 testhead is shown in Figure 1-3.

Figure 1-3

Testhead front panel

CURRENT

OUTPUT

!

CAT I

VOLTAG E

SENSE

LO

LO

BIAS

DETECTOR 1 DETECTOR 2

ISOLATION FROM EARTH: 10V MAX.

CURRENT

INPUT

!

HI

HI

DETECTOR connectors:

DETECTOR 1 Use to bias and measure photodiode detector #1.
DETECTOR 2 Use to bias and measure photodiode detector #2.

Triax connector terminals: Center conductor – Current input

Inner shell – Voltage bias source output.
Outer shell – Chassis ground.

WARNING Isolation from earth is 10V maximum. Exceeding this value may result

in a shock hazard.

Laser diode connectors:

CURRENT OUTPUT Current source HI and LO output terminals to laser diode.
VOLTAGE SENSE HI and LO sense terminals to measure laser diode voltage.

BNC connector terminals: Center conductor – Signal input or output.

Outer shell – Chassis ground.

1-10 Getting Started Model 2520 User’s Manual

Rear panel summary

The rear panel of the Model 2520 testhead is shown in Figure 1-4.

Figure 1-4

Testhead rear panel

DISABLED

(PULL TO

KEY

INTERLOCK

INTERLOCK

STATUS

REMOVE)

ENABLED

LASER

POWER

ON

BOTH INTERLOCKS MUST BE ENABLED TO OPERATE

!

REMOTE

INTERLOCK

DISABLED

19

ENABLED

MAINFRAME

CONN 2

GREEN=ENABLED
RED=DISABLED

MAINFRAME

CONN 1

MAINFRAME connectors:

MAINFRAME CONN 1 Connects to mainframe TESTHEAD CONN 1 connector.
MAINFRAME CONN 2 Connects to mainframe TESTHEAD CONN 2 connector.

INTERLOCKS:

REMOTE INTERLOCK DB-9 connector for a remote interlock switch.
KEY INTERLOCK Key interlock switch (key must be inserted and rotated to ENABLED

position to operate).

NOTE Both interlocks must be enabled to operate.

Indicator lights:

INTERLOCK STATUS Shows interlock status. Glows blue when disabled (source outputs

cannot be turned on). Glows green when enabled (source outputs
can be turned on).

LASER POWER ON Indicates when source outputs are turned on.

WARNING If at any time the indicators provided on the testhead, for INTER-

LOCK STATUS or LASER POWER ON, should fail to light or to
properly indicate status, immediately contact a Keithley service repre­sentative for repair. Failure to do so may expose the user to hazards
without proper warnings.

See “Interlock status indicator test sequence,” page 9-7, for instructions on verification of
correct operation of the indicators.

Model 2520 User’s Manual Getting Started 1-11

Power-up

Line voltage

The Model 2520 operates from a line voltage in the range of 100V to 240V at a frequency
of 50 or 60Hz. Line voltage selection is automatic.

CAUTION Operating the instrument on an incorrect line voltage may cause dam-

age, possibly voiding the warranty.

Line power connection

Perform the following steps to connect the Model 2520 to line power and turn it on:

1. Before plugging in the power cord, make sure the rear panel power switch (located

in the power module) is in the off (0) position.

2. Connect the female end of the supplied power cord to the AC receptacle on the rear

panel.

WARNING The power cord supplied with the Model 2520 contains a separate

ground for use with grounded outlets. When proper connections are
made, instrument chassis is connected to power line ground through
the ground wire in the power cord. Failure to use a grounded outlet
may result in personal injury or death due to electric shock.

3. Turn on the instrument by pressing the rear panel power switch to the on (1) posi-

tion.

Power-up sequence

On power-up, the Model 2520 performs self-tests on its EPROM and RAM and momen­tarily lights all segments and annunciators. If a failure is detected, the instrument momen­tarily displays an error message, and the ERR annunciator turns on. Error messages are
listed in Appendix B.

NOTE If a problem develops while the instrument is under warranty, return it to

Keithley Instruments, Inc., for repair.

If the instrument passes the self-tests, the firmware revision levels are displayed. For
example:

REV A01 A02 A03

where: A01 is the main processor ROM revision.

A02 is the DSP ROM revision.

A03 is the display board ROM revision.

1-12 Getting Started Model 2520 User’s Manual

The communication interface status is briefly displayed. If the IEEE-488 bus is the pres­ently selected interface, the identification message will include the primary address. For
example, if the primary address is 25 (factory default), the “IEEE Addr=25” message is
displayed. If the RS-232 interface is selected, the “RS-232” message is displayed.

After the power-up sequence, the instrument goes to its normal display state with the out­put off (blue ON/OFF OUTPUT indicator and testhead POWER lights off).

System identification

To obtain the serial number and revision information, use the MENU/SERIAL # selection
or the *IDN? query via remote.

Fuse replacement

A rear panel fuse protects the power line input of the Model 2520. If the line fuse needs to
be replaced, perform the steps below:

WARNING Disconnect the line cord and all cables and test leads from the instru-

ment before changing the line fuse.

1. The fuse is located in a holder in the power module adjacent to the AC receptacle
(Figure 1-2.) At the right of the fuse holder is a small tab. At this location, use a
small bladed screwdriver to release the fuse holder.

2. Slide the fuse holder out to gain access to the fuse carrier and fuse.

3. Remove the carrier with blown fuse, and replace the fuse with the correct type
listed in Table 1-1.

CAUTION For continued protection against fire or instrument damage, replace

the fuse only with the type and rating listed. If the instrument repeat­edly blows fuses, locate and correct the cause of the problem before
replacing the fuse.

4. Install the fuse carrier in the fuse holder, then insert the fuse holder in the power
module.

Table 1-1

Line fuse

Line voltage Fuse rating Keithley part no.

100-240V 1.6A slow blow, 250V, 5 X 20mm FU-106-1.6