Anritsu 680 B Series User manual

SERIES
680XXB/681XXB
SYNTHESIZED CW/SWEEP GENERATORS
MAINTENANCE MANUAL
P/N: 10370-10262
REVISION: F
PRINTED: AUGUST 2003
COPYRIGHT 2003 ANRITSU CO.
490 JARVIS DRIVE
MORGAN HILL, CA 95037-2809

WARRANTY
The ANRITSU product(s) listed on the title page is (are) warranted against defects in materials and
workmanship for one year from the date of shipment.
ANRITSU's obligation covers repairing or replacing products which prove to be defective during the
warranty period. Buyers shall prepay transportation charges for equipment returned to ANRITSU
for warranty repairs. Obligation is limited to the original purchaser. ANRITSU is not liable for con-
sequential damages.
LIMITATION OF WARRANTY
The foregoing warranty does not apply to ANRITSU connectors that have failed due to normal wear.
Also, the warranty does not apply to defects resulting from improper or inadequate maintenance by
the Buyer, unauthorized modification or misuse, or operation outside of the environmental specifi-
cations of the product. No other warranty is expressed or implied, and the remedies provided herein
are the Buyer's sole and exclusive remedies.
TRADEMARK ACKNOWLEDGEMENTS
Adobe Acrobat is a registered trademark of Adobe Systems Incorporated.
NOTICE
ANRITSU Company has prepared this manual for use by ANRITSU Company personnel and cus-
tomers as a guide for the proper installation, operation, and maintenance of ANRITSU Company
equipment and computor programs. The drawings, specifications, and information contained herein
are the property of ANRITSU Company, and any unauthorized use or disclosure of these drawings,
specifications, and information is prohibited; they shall not be reproduced, copied, or used in whole
or in part as the basis for manufacture or sale of the equipment or software programs without the
prior writtten consent of ANRITSU Company.

Table of Contents
Chapter 1 - General Information
1-1 SCOPE OF MANUAL.................1-3
1-2 INTRODUCTION ...................1-3
1-3 DESCRIPTION ....................1-3
1-4 IDENTIFICATION NUMBER ............1-6
1-5 ELECTRONIC MANUAL...............1-6
1-6 RELATED MANUALS ................1-6
Operation Manual ................1-6
GPIB Programming Manual ...........1-6
SCPI Programming Manual ...........1-6
1-7 OPTIONS .......................1-7
1-8 LEVEL OF MAINTENANCE.............1-8
Troubleshooting .................1-8
Repair......................1-8
Calibration ...................1-8
Preventive Maintenance .............1-8
1-9 PREVENTIVE MAINTENANCE...........1-9
1-10 STATIC-SENSITIVE COMPONENT HANDLING
PRECAUTIONS ...................1-9
1-11 STARTUP CONFIGURATIONS...........1-11
1-12 RECOMMENDED TEST EQUIPMENT ......1-12
1-13 EXCHANGE ASSEMBLY PROGRAM .......1-14
1-14 REPLACEABLE SUBASSEMBLIES AND PARTS 1-15
Chapter 2 - Functional Description
2-1 INTRODUCTION ...................2-3
2-2 680XXB/681XXB MAJOR SUBSYSTEMS ......2-3
Digital Control..................2-4
Front Panel ...................2-4
Frequency Synthesis...............2-4
Analog Instruction ...............2-5
YIG Driver ...................2-10
ALC/Modulation ................2-10
680XXB/681XXB MM i

RF Deck ....................2-10
Power Supply..................2-11
Inputs/Outputs .................2-11
Motherboard/Interconnections..........2-12
2-3 FREQUENCY SYNTHESIS.............2-12
Phase Lock Loops................2-12
Overall Operation ...............2-15
RF Outputs 0.01 to 65 GHz...........2-17
Frequency Modulation (681XXB only) ......2-18
Analog Sweep Mode (681XXB only) .......2-18
Step Sweep Mode................2-18
2-4 ALC AND MODULATION..............2-19
ALC Loop Operation ..............2-19
Amplitude Modulation (681XXB only)......2-20
Square Wave Modulation (681XXB only) ....2-23
2-5 RF DECK ASSEMBLIES ..............2-24
RF Deck Configurations ............2-24
YIG-tuned Oscillator ..............2-27
Power Level Control and Modulation ......2-27
RF Signal Filtering...............2-28
0.01 to 2 GHz Down Converter .........2-29
0.5 to 2.2 GHz Digital Down Converter .....2-29
Switched Doubler Module............2-30
Source Quadrupler Module ...........2-33
Power Level Detection/ALC Loop ........2-35
Step Attenuator ................2-35
Chapter 3 - Performance Verification
3-1 INTRODUCTION ...................3-3
3-2 RECOMMENDED TEST EQUIPMENT .......3-3
3-3 TEST RECORDS ...................3-3
3-4 CONNECTOR AND KEY LABEL NOTATION . . . 3-3
3-5 680XXB/681XXB POWER LEVELS .........3-6
3-6 INTERNAL TIME BASE AGING RATE TEST . . . 3-8
Test Setup....................3-8
Test Procedure..................3-9
ii 680XXB/681XXB MM
Table of Contents (Continued)

3-7 FREQUENCY SYNTHESIS TESTS ........3-11
Test Setup ...................3-11
Coarse Loop/ YIG Loop Test Procedure .....3-12
Fine Loop Test Procedure ............3-13
3-8 SPURIOUS SIGNALS TEST: RF OUTPUT SIGNALS
£2 GHz (£2.2 GHz for 68XX5B MODELS).....3-14
Test Setup ...................3-14
0.01 -2 GHz Test Procedure ...........3-14
0.5 - 2.2 GHz Test Procedure ..........3-17
3-9 HARMONIC TEST: RF OUTPUT SIGNALS
FROM2TO20GHz................3-18
Test Setup ...................3-18
Test Procedure (2 to 10 GHz) ..........3-19
Test Procedure (11 to 20 GHz) .........3-20
3-10 SINGLE SIDEBAND PHASE NOISE TEST ....3-22
Test Setup ...................3-22
Test Procedure .................3-23
3-11 POWER LEVEL ACCURACY AND FLATNESS
TESTS........................3-26
Test Setup ...................3-26
Power Level Accuracy Test Procedure ......3-27
Power Level Flatness Test Procedure ......3-27
Chapter 4 - Calibration
4-1 INTRODUCTION ...................4-3
4-2 RECOMMENDED TEST EQUIPMENT .......4-3
4-3 TEST RECORDS ...................4-3
4-4 CALIBRATION FOLLOWING SUBASSEMBLY
REPLACEMENT...................4-4
4-5 CONNECTOR AND KEY LABEL NOTATION . . . 4-4
4-6 INITIAL SETUP....................4-7
Interconnection .................4-7
PC Setup — Windows 3.1 ............4-8
PC Setup — Windows 95 ............4-10
4-7 PRELIMINARY CALIBRATION ..........4-13
Equipment Setup................4-13
Calibration Steps................4-14
680XXB/681XXB MM iii
Table of Contents (Continued)

4-8 SWITCHED FILTER SHAPER CALIBRATION . . 4-17
Equipment Setup................4-17
Log Amplifier Zero Calibration .........4-18
Limiter DAC Adjustment ............4-18
Shaper DAC Adjustment ............4-19
4-9 RF LEVEL CALIBRATION .............4-22
4-10 ALC SLOPE CALIBRATION ............4-23
Equipment Setup................4-23
ALC Slope DAC Adjustment ..........4-24
4-11 ALC BANDWIDTH CALIBRATION ........4-31
Equipment Setup................4-31
Bandwidth Calibration .............4-31
4-12 AM CALIBRATION .................4-33
Equipment Setup................4-33
AM Calibration DAC Adjustment ........4-34
4-13 FM CALIBRATION .................4-41
Equipment Setup................4-41
FM Calibration Procedure ...........4-42
Chapter5-Troubleshooting
5-1 INTRODUCTION ...................5-3
5-2 RECOMMENDED TEST EQUIPMENT .......5-3
5-3 ERROR AND WARNING/STATUS MESSAGES. . . 5-3
Self-Test Error Messages.............5-3
Normal Operation Error and Warning/
Status Messages ................5-7
5-4 MALFUNCTIONS NOT DISPLAYING AN
ERROR MESSAGE .................5-9
5-5 TROUBLESHOOTING TABLES ...........5-9
Chapter 6 - Removal and Replacement Procedures
6-1 INTRODUCTION ...................6-3
6-2 REMOVING AND REPLACING THE CHASSIS
COVERS .......................6-4
Preliminary ...................6-4
Procedure ....................6-4
iv 680XXB/681XXB MM
Table of Contents (Continued)

6-3 REMOVING AND REPLACING THE FRONT
PANEL ASSEMBLY .................6-6
Preliminary ...................6-6
Procedure ....................6-6
6-4 REMOVING AND REPLACING THE A3, A4, A5,
ORA6PCB......................6-8
Preliminary ...................6-8
Procedure ....................6-8
6-5 REMOVING AND REPLACING THE A7 PCB. . . 6-10
Preliminary ..................6-10
Procedure ...................6-10
6-6 REMOVING AND REPLACING THE A9, A10,
A11,ORA12PCB..................6-10
Preliminary ..................6-10
Procedure ...................6-10
6-7 REMOVING AND REPLACING THE A13, A14,
ORA15PCB ....................6-11
Preliminary...................6-11
Procedure ...................6-11
6-8 REMOVING AND REPLACING THE A16
ORA17PCB ....................6-11
Preliminary...................6-11
Procedure ...................6-11
6-9 REMOVING AND REPLACING THE A18
ORA19PCB....................6-12
Preliminary ..................6-12
Procedure ...................6-12
6-10 REMOVING AND REPLACING THE REAR
PANEL ASSEMBLY ................6-13
Preliminary ..................6-13
Procedure ...................6-13
6-11 REMOVING AND REPLACING THE A21 PCB . . 6-17
Preliminary ..................6-17
Procedure ...................6-17
680XXB/681XXB MM v
Table of Contents (Continued)

6-12 REMOVING AND REPLACING THE A21-1/
A21-2 PCB .....................6-18
Preliminary ..................6-18
Procedure ...................6-18
6-13 REMOVING AND REPLACING THE FAN
ASSEMBLY .....................6-19
Preliminary ..................6-19
Procedure ...................6-19
Appendix A - Test Records
A-1 INTRODUCTION...................A-1
vi 680XXB/681XXB MM
Table of Contents (Continued)

Table of Contents
1-1 SCOPE OF MANUAL.................1-3
1-2 INTRODUCTION ...................1-3
1-3 DESCRIPTION ....................1-3
1-4 IDENTIFICATION NUMBER ............1-6
1-5 ELECTRONIC MANUAL...............1-6
1-6 RELATED MANUALS ................1-6
Operation Manual ................1-6
GPIB Programming Manual ...........1-6
SCPI Programming Manual ...........1-6
1-7 OPTIONS .......................1-7
1-8 LEVEL OF MAINTENANCE.............1-8
Troubleshooting .................1-8
Repair......................1-8
Calibration ...................1-8
Preventive Maintenance .............1-8
1-9 PREVENTIVE MAINTENANCE...........1-9
1-10 STATIC-SENSITIVE COMPONENT HANDLING
PRECAUTIONS ...................1-9
1-11 STARTUP CONFIGURATIONS...........1-11
1-12 RECOMMENDED TEST EQUIPMENT ......1-12
1-13 EXCHANGE ASSEMBLY PROGRAM .......1-14
1-14 REPLACEABLE SUBASSEMBLIES AND
PARTS........................1-15
Chapter 1
General Information

Figure 1-1. Typical Series 680XXB/681XXB Synthesized CW/Sweep Generator (Model 68169B Shown)

Chapter 1
General Information
1-1 SCOPE OF MANUAL This manual provides service information for all models of the Series
680XXB Synthesized CW Generator and the Series 681XXB Synthe-
sized Sweep Generator. The service information includes replaceable
parts information, functional circuit descriptions, block diagrams, per-
formance verification tests, and procedures for calibration, trouble-
shooting, and assembly/subassembly removal and replacement.
(Throughout this manual, the term 680XXB/681XXB is used to refer
to the instrument.) Manual organization is shown in the table of con-
tents.
NOTE
Service information for the series 680XXB CW generators
and series 681XXB sweep generators is combined into one
manual because identical model numbers of each series con-
tain the same assemblies, subassemblies, and components.
Differences between the series are noted where applicable
throughout the manual.
1-2 INTRODUCTION This chapter provides a general description of the Series 680XXB/
681XXB Synthesized CW/Sweep Generators, identification numbers,
related manuals, and options. Information is included concerning level
of maintenance, replaceable subassemblies and RF components, ex-
change assembly program, and preventive maintenance. Static-
sensitive component handling precautions and lists of exchangeable
subassemblies and recommended test equipment are also provided.
1-3 DESCRIPTION The Series 680XXB Synthesized CW Generator and the Series
681XXB Synthesized Sweep Generator are microprocessor-based,
synthesized signal sources with high resolution phase-lock capability.
They generate both discrete CW frequencies and broad (full range)
and narrow band sweeps across the frequency range of 10 MHz to
65 GHz. All functions of the 680XXB/681XXB are fully controllable
locally from the front panel or remotely (except for power on/standby)
via the IEEE-488 General Purpose Interface Bus (GPIB).
The Series 680XXB Synthesized CW Generator and the Series
681XXB Synthesized Sweep Generator each presently consists of 15
models covering a variety of frequency ranges and power levels. Table
1-1, on pages 1-4 and 1-5, lists models, frequency ranges, and maxi-
mum leveled output.
680XXB/681XXB MM 1-3

1-4 680XXB/681XXB MM
GENERAL 680XXB/681XXB
INFORMATION MODELS
68XXXB
Model Frequency (GHz) Output Power Output Power
w/Step Attenuator
68X37B 2.0 – 20.0 GHz +13.0 dBm +11.0 dBm
68X45B 0.5 – 20.0 GHz +13.0 dBm +11.0 dBm
68X47B 0.01 – 20.0 GHz +13.0 dBm +11.0 dBm
68X53B 2.0 – 20.0 GHz
20.0 – 26.5 GHz +9.0 dBm +6.0 dBm +7.0 dBm +3.5 dBm
68X55B 0.5 – 2.2 GHz 2.2 – 20.0 GHz
20.0 – 26.5 GHz
+13.0 dBm
+9.0 dBm
+6.0 dBm
+11.0 dBm
+7.0 dBm
+3.5 dBm
68X59B 0.01 – 2.0 GHz 2.0 – 20.0 GHz
20.0 – 26.5 GHz
+13.0 dBm
+9.0 dBm
+6.0 dBm
+11.0 dBm
+7.0 dBm
+3.5 dBm
68X63B 2.0 – 20.0 GHz
20.0 – 40.0 GHz +9.0 dBm +6.0 dBm +7.0 dBm +3.0 dBm
68X65B 0.5 – 2.2 GHz 2.2 – 20.0 GHz
20.0 – 40.0 GHz
+13.0 dBm
+9.0 dBm
+6.0 dBm
+11.0 dBm
+7.0 dBm
+3.0 dBm
68X69B 0.01 – 2.0 GHz 2.0 – 20.0 GHz
20.0 – 40.0 GHz
+13.0 dBm
+9.0 dBm
+6.0 dBm
+11.0 dBm
+7.0 dBm
+3.0 dBm
68X75B
0.5 – 2.2 GHz
2.2 – 20.0 GHz
20.0 – 40.0 GHz
40.0 – 50.0 GHz
+11.0 dBm
+10.0 dBm
+2.5 dBm
+2.5 dBm
+10.0 dBm
+8.5 dBm
0.0 dBm
–1.0 dBm
68X77B
0.01 – 2.0 GHz
2.0 – 20.0 GHz
20.0 – 40.0 GHz
40.0 – 50.0 GHz
+12.0 dBm
+10.0 dBm
+2.5 dBm
+2.5 dBm
+10.0 dBm
+8.5 dBm
0.0 dBm
–1.0 dBm
68X85B
0.5 – 2.2 GHz
2.2 – 20.0 GHz
20.0 – 40.0 GHz
40.0 – 50.0 GHz
50.0 – 60.0 GHz
+11.0 dBm
+10.0 dBm
+2.5 dBm
+2.0 dBm
+2.0 dBm
+10.0 dBm
+8.5 dBm
0.0 dBm
–1.5 dBm
–2.0 dBm
68X87B
0.01 – 2.0 GHz
2.0 – 20.0 GHz
20.0 – 40.0 GHz
40.0 – 50.0 GHz
50.0 – 60.0 GHz
+12.0 dBm
+10.0 dBm
+2.5 dBm
+2.0 dBm
+2.0 dBm
+10.0 dBm
+8.5 dBm
0.0 dBm
–1.5 dBm
–2.0 dBm
68X95B
0.5 – 2.2 GHz
2.2 – 20.0 GHz
20.0 – 40.0 GHz
40.0 – 50.0 GHz
50.0 – 65.0 GHz
+11.0 dBm
+10.0 dBm
+2.5 dBm
0.0 dBm
–2.0 dBm
Not Available
Table 1-1. Series 680XXB/681XXB Models (1 of 2)

680XXB/681XXB MM 1-5
GENERAL 680XXB/681XXB
INFORMATION MODELS
68XXXB
Model Frequency (GHz) Output Power Output Power
w/Step Attenuator
68X97B
0.01 – 2.0 GHz
2.0 – 20.0 GHz
20.0 – 40.0 GHz
40.0 – 50.0 GHz
50.0 – 65.0 GHz
+12.0 dBm
+10.0 dBm
+2.5 dBm
0.0 dBm
–2.0 dBm
Not Available
With Option 15A (High Power) Installed
68X37B 2.0 – 20.0 GHz +17.0 dBm +15.0 dBm
68X45B 0.5 – 2.2 GHz
2.2 – 20.0 GHz +13.0 dBm +17.0 dBm +11.0 dBm +15.0 dBm
68X47B 0.01 – 2.0 GHz
2.0 – 20.0 GHz +13.0 dBm +17.0 dBm +11.0 dBm +15.0 dBm
68X53B 2.0 – 20.0 GHz
20.0 – 26.5 GHz +13.0 dBm +10.0 dBm +11.0 dBm +7.5 dBm
68X55B 0.5 – 2.2 GHz 2.2 – 20.0 GHz
20.0 – 26.5 GHz
+13.0 dBm
+13.0 dBm
+10.0 dBm
+11.0 dBm
+11.0 dBm
+7.5 dBm
68X59B 0.01 – 2.0 GHz 2.0 – 20.0 GHz
20.0 – 26.5 GHz
+13.0 dBm
+13.0 dBm
+10.0 dBm
+11.0 dBm
+11.0 dBm
+7.5 dBm
68X63B 2.0 – 20.0 GHz
20.0 – 40.0 GHz +13.0 dBm +6.0 dBm +11.0 dBm +3.0 dBm
68X65B 0.5 – 2.2 GHz 2.2 – 20.0 GHz
20.0 – 40.0 GHz
+13.0 dBm
+13.0 dBm
+6.0 dBm
+11.0 dBm
+11.0 dBm
+3.0 dBm
68X69B 0.01 – 2.0 GHz 2.0 – 20.0 GHz
20.0 – 40.0 GHz
+13.0 dBm
+13.0 dBm
+6.0 dBm
+11.0 dBm
+11.0 dBm
+3.0 dBm
68X75B 0.5 – 50.0 GHz Standard Standard
68X77B 0.01 – 50.0 GHz Standard Standard
68X85B 0.5 – 60.0 GHz Standard Standard
68X87B 0.01 – 60.0 GHz Standard Standard
68X95B 0.5 – 65.0 GHz Standard Not Available
68X97B 0.01 – 65.0 GHz Standard Not Available
Table 1-1. Series 680XXB/681XXB Models (2 of 2)

1-4 IDENTIFICATION NUMBER All ANRITSU instruments are assigned a unique six-digit ID number,
such as “403002”. The ID number is imprinted on a decal that is af-
fixed to the rear panel of the unit. Special-order instrument configura-
tions also have an additional special serial number tag attached to the
rear panel of the unit.
When ordering parts or corresponding with ANRITSU Customer Serv-
ice, please use the correct serial number with reference to the specific
instrument's model number (i.e., Model 68147B Synthesized Sweep
Generator, Serial No. 403002).
1-5 ELECTRONIC MANUAL This manual is available on CD ROM as an Adobe Acrobat Portable
Document Format (*.pdf) file. The file can be viewed using Acrobat
Reader, a free program that is also included on the CD ROM. The file
is “linked” such that the viewer can choose a topic to view from the
displayed “bookmark” list and “jump” to the manual page on which the
topic resides. The text can also be word-searched. Contact ANRITSU
Customer Service for price and availability.
1-6 RELATED MANUALS This is one of a four manual set that consists of an Operation Manual,
a GPIB Programming Manual, a SCPI Programming Manual, and a
Maintenance Manual.
Operation
Manual This manual provides instructions for operation of
the 680XXB/681XXB using the front panel controls.
It also includes general information, performance
specifications, installation instructions, and opera-
tion verification procedures. The ANRITSU part
number for the Series 680XXB Operation Manual is
10370-10264; the part number for the Series
681XXB Operation Manual is 10370-10298.
GPIB
Programming
Manual
This manual provides information for remote opera-
tion of the 680XXB/681XXB using Product Specific
commands sent from an external controller via the
IEEE 488 General Purpose Interface Bus (GPIB). It
contains a complete listing and description of all
680XXB/681XXB GPIB Product Specific commands
and several programming examples. The ANRITSU
part number for the Series 680XXB GPIB Program-
ming Manual is 10370-10266; the part number for
the Series 681XXB GPIB Programming Manual is
10370-10260.
SCPI
Programming
Manual
This manual provides information for remote opera-
tion of the 680XXB/681XXB using Standard Com-
mands for Programmable Instruments (SCPI)
commands sent from an external controller via the
1-6 680XXB/681XXB MM
GENERAL IDENTIFICATION
INFORMATION NUMBER

IEEE 488 General Purpose Interface Bus (GPIB). It
contains a complete listing and description of each
command in the 680XXB/681XXB SCPI command
set and examples of command usage. The ANRITSU
part number for the Series 680XXB SCPI Program-
ming Manual is 10370-10272; the part number for
the Series 681XXB SCPI Programming Manual is
10370-10274.
1-7 OPTIONS The following instrument options are available.
qOption 1, Rack Mounting. Rack mount kit containing a set of
track slides (90°tilt capability), mounting ears, and front panel
handles for mounting the instrument in a standard 19-inch
equipment rack.
qOption 2A, 110 dB Step Attenuator. Adds a 10 dB per step
attenuator with a 110 dB range for models having a high-end fre-
quency of £26 5 GHz. Output power is selected directly in dBm
on the front panel (or via GPIB). Rated output power is reduced.
qOption 2B, 110 dB Step Attenuator. Adds a 10 dB per step
attenuator with a 110 dB range for models having a high-end fre-
quency of 40 GHz. Output power is selected directly in dBm on
the front panel (or via GPIB). Rated output power is reduced.
qOption 2C, 90 dB Step Attenuator. Adds a 10 dB per step
attenuator with a 90 dB range for models having a high-end fre-
quency of 50 GHz. Output power is selected directly in dBm on
the front panel (or via GPIB). Rated output power is reduced.
qOption 2D, 90 dB Step Attenuator. Adds a 10 dB per step
attenuator with a 90 dB range for models having a high-end fre-
quency of 60 GHz. Output power is selected directly in dBm on
the front panel (or via GPIB). Rated output power is reduced.
qOption 9, Rear Panel RF Output. Moves the RF output con-
nector to the rear panel.
qOption 11, 0.1 Hz Frequency Resolution. Provides frequency
resolution of 0.1 Hz.
qOption 14, ANRITSU 360B VNA Compatibility. Modifies rack
mounting hardware to mate unit in a ANRITSU 360B VNA con-
sole.
qOption 15A, High Power Output. Adds high-power RF compo-
nents to the instrument in the 2–26.5 GHz frequency range. Op-
tion 15A is standard in models having a high-end frequency that
is >40 GHz.
qOption 16, High-Stability Time Base. Adds an ovenized,
10 MHz crystal oscillator with <5 x 10–10/day frequency stability.
680XXB/681XXB MM 1-7
GENERAL
INFORMATION OPTIONS

qOptions 17A & 17B, No Front Panel. Deletes the front panel
for use in remote control applications where a front panel display
or keyboard control are not needed. Option 17A deletes the front
panel from 681XXB models; Option 17B deletes the front panel
from 680XXB models.
qOption 18, mmWave Module Bias Output. Provides bias out-
put for 54000-xWRxx Millimeter Wave Source Modules. BNC
Twinax connector, rear panel.
qOption 19, SCPI Programmability. Adds GPIB command
mnemonics complying with Standard Commands for Program-
mable Instruments (SCPI), Version 1993. SCPI programming
complies with IEEE 488.2-1987.
1-8 LEVEL OF MAINTENANCE Maintenance of the 680XXB/681XXB consists of:
qTroubleshooting the instrument to a replaceable subassembly or
RF component.
qRepair by replacing the failed subassembly or RF component.
qCalibration.
qPreventive maintenance.
Troubleshoot-
ing The 680XXB/681XXB firmware includes internal di-
agnostics that self-test most of the internal assem-
blies of the instrument. When the 680XXB/681XXB
fails self-test, one or more error messages are dis-
played to aid in troubleshooting the failure to a re-
placeable subassembly or RF component. Chapter
5–Troubleshooting lists and describes the self-test
error messages and provides procedures for isolat-
ing 680XXB/681XXB failures to a replaceable subas-
sembly or RF component.
Repair Most instrument failures are field repairable by re-
placing the failed subassembly or RF component.
Detailed instructions for removing and replacing
failed subassemblies and components are provided
in Chapter 6–Removal and Replacement Proce-
dures.
Calibration The 680XXB/681XXB may require calibration after
repair. Refer to Chapter 4–Calibration for a listing
of calibration requirements and calibration proce-
dures.
Preventive
Maintenance Preventive maintenance on the 680XXB/681XXB
consists of cleaning the fan honeycomb filter, de-
scribed in paragraph 1-9.
1-8 680XXB/681XXB MM
GENERAL LEVEL OF
INFORMATION MAINTENANCE

1-9 PREVENTIVE
MAINTENANCE The 680XXB/681XXB must always receive adequate ventilation. A blocked fan filter can cause the instrument to overheat and shut down.
Check and clean the rear panel fan honeycomb filter periodically.
Clean the fan honeycomb filter more frequently in dusty environ-
ments. Clean the filter as follows.
Step 1 Remove the filter guard from the rear panel by pull-
ing out on the four panel fasteners holding them in
place (Figure 1-2).
Step 2 Vacuum the honeycomb filter to clean it.
Step 3 Install the filter guard back on the rear panel.
Step 4 Press in on the panel fasteners to secure the filter
guard to the rear panel.
1-10 STATIC-SENSITIVE
COMPONENT
HANDLING
PRECAUTIONS
The 680XXB/681XXB contains components that can be damaged by
static electricity. Figure 1-3 illustrates the precautions that should be
followed when handling static-sensitive subassemblies and compo-
nents. If followed, these precautions will minimize the possibilities of
static-shock damage to these items.
NOTE
Use of a grounded wrist strap when removing and/or replac-
ing subassemblies or components is strongly recommended.
680XXB/681XXB MM 1-9
GENERAL PREVENTIVE
INFORMATION MAINTENANCE
Panel
Fastener (4)
Filter
Guard
Figure 1-2. Removing/Replacing the Fan Filter Guard

1-10 680XXB/681XXB MM
GENERAL STATIC-SENSITIVE COMPONENT
INFORMATION HANDLING PRECAUTIONS
1. Do not touch exposed contacts
on any static sensitive
component.
2. Do not slide static sensitive
component across any surface. 3. Do not handle static sensitive components in areas where the
floor or work surface covering
is capable of generating a
static charge.
4. Wear a static-discharge
wristband when working with
static sensitive components.
5. Label all static sensitive
devices. 6. Keep component leads shorted together whenever possible.
7. Handle PCBs only by their
edges. Do not handle by the
edge connectors.
8. Lift & handle solid state de-
vices by their bodies – never
by their leads.
9. Transport and store PCBs and
other static sensitive devices in
static-shielded containers.
10. ADDITIONAL PRECAUTIONS:
Keep workspaces clean and free of any objects capable of holding or storing a static charge.
Connect soldering tools to an earth ground.
Use only special anti-static suction or wick-type desoldering tools.
Figure 1-3. Static-Sensitive Component Handling Precautions