BRUEL & KJAER 7521 User manual

Brüel&Kjær
BI5040–12e
Technical
Documentation
WORLD HEADQUARTERS: DK-2850 Nærum • Denmark •
Telephone: [phone] •Telex: 37316 bruka dk • Fax: [phone] •
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Signal Analyzer Interface Unit
Type 7521
Service Manual

0−2Brüel & KjærSignal Analyzer Interface Unit Type 7521
Service Manual
Proprietary: Authorized Brüel & Kjær Personnel Only

April 1997
BI5040–12e
Brüel & Kjær Signal Analyzer Interface Unit Type 7521
Service Manual
Signal Analyzer Interface Unit
Type 7521
Service Manual
Valid from serial number 1 627 589

0−2Brüel & KjærSignal Analyzer Interface Unit Type 7521
Service Manual
Safety Considerations
This apparatus has been designed and tested in accordance with IEC Publication
348, Safety Requirements for Electronic Measuring Apparatus, and has been supplied
in safe condition. This Guide contains information and warnings which must be fol-
lowed by the user to ensure safe operation and to retain the apparatus in safe
condition. Special note should be made of the following:
Safety Symbols
See the associated warning statements given in the User Guide.
Chassis Terminal
Safety Earth Terminal
Hazardous Voltage
Warnings
This is a CISPR II, Class A product. In a domestic environment this product may
cause radio interference in which case the user may be required to take adequate
measures
Switch off all power to equipment before connecting or disconnecting their digital
interface. Failure to do so could damage the equipment.
Whenever it is likely that the correct function or operating safety of the apparatus
has been impaired, it must be made inoperative and be secured against unintended
operation.
Any adjustment maintenance and repair of the open apparatus under voltage must
be avoided as far as possible and, if unavoidable, must be carried out only by trained
service personnel.
Copyright © 1997, Brüel&Kjær Sound and Vibration Measurement A/S
All rights reserved. No part of this publication may be reproduced or distributed in
any form or by any means without prior consent in writing from Brüel & Kjær Sound
and Vibration Measurement A/S, Nærum, Denmark.

Signal Analyzer Interface Unit Type 7521
Service Manual
BI5040–12e 0−3
Contents
1. General Information.................................................................................................. 1–1
1.1 Introduction................................................................................................................. 1–2
1.2 Edition Number........................................................................................................... 1–2
1.3 Safety ........................................................................................................................... 1–3
1.4 Service Policy and FRP Number ................................................................................ 1–3
1.5 Special Tools and Equipment..................................................................................... 1–3
2. Service Note...................................................................................................................... 2–1
2.1 On-line Editions of the Service Manual..................................................................... 2–2
2.2 Printed Editions of the Service Manual..................................................................... 2–2
3. Checking Procedure................................................................................................... 3–1
3.1 Preparation.................................................................................................................. 3–2
3.2 Procedure..................................................................................................................... 3–2
The Digital Part of the 7521 .................................................................................. 3–2
The Analog Part of the 7521.................................................................................. 3–3
4. Adjustment Procedure............................................................................................. 4–1
4.1 Introduction................................................................................................................. 4–2
4.2 Preparation.................................................................................................................. 4–2
4.3 Procedure..................................................................................................................... 4–2
The Trigger Input................................................................................................... 4–2
The Sampling Input ............................................................................................... 4–3
The Delay Adjustment ........................................................................................... 4–4
5. Mechanical Parts.......................................................................................................... 5–1
5.1 Chassis Parts............................................................................................................... 5–2
5.2 Spare Parts.................................................................................................................. 5–3

Signal Analyzer Interface Unit Type 7521
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6. Theory of Operation................................................................................................... 6–1
6.1 Functional Description ............................................................................................... 6–2
Description of the Blocks...................................................................................... 6–2
Digital Part............................................................................................................. 6–3

Signal Analyzer Interface Unit Type 7521
Service Manual
BI5040–12e 1−1
Chapter 1
General Information

Chapter 1 — General Information
Introduction
Signal Analyzer Interface Unit Type 7521
Service Manual Brüel & Kjær
1−2
1.1 Introduction
The 7521 is a Signal Analyzer Interface Module, always located in slot 0 of an
acquisition unit. Type 7521 enables communication between the modules in the
acquisition unit (Type 2816 or Type 2825), and a signal analyzer, for example Type
2035.
Type 7521 has a Trigger input, a Sampling input and a Sampling output. A
Delay Adj. control enables the delay of the external sampling signal to be adjusted.
The two LEDs indicate if the acquisition unit to which the Type 7521 is connected
is viewed as Unit 1 or Unit 2, as seen from the analyzer.
1.2 Edition Number
If any major changes are made to the instrument and/or Service Manual, a new
edition of the Service Manual will be released. Any new edition can be recognised
by the Literature Number (BI5040-xx) given at the bottom of odd numbered pages.
The serial number from which each edition is valid is printed in the Frontispiece of
this Service Manual.
Fig.1.1 Type 7521

Chapter 1 — General Information
Safety
Signal Analyzer Interface Unit Type 7521
Service Manual
BI5040–12e 1−3
Information concerning minor changes will be released in the form of a Service
Note which is dealt with in section 2.1.
1.3 Safety
Type 3028 has been designed and tested in accordance with IEC Publication 348,
Safety Requirements for Electronic Measuring Apparatus, and has been supplied in
safe condition.
Any work done on the instrument when open must be done by a qualified person
who is aware of the hazards involved.
Note: The word WARNING denotes a hazard. It calls attention to a procedure,
practice, or like, which, if not correctly performed or adhered to, could result in
personal injury.
1.4 Service Policy and FRP Number
Type 7521 is a Field Replaceable Part (FRP). To assure economical reuse, it is
important that no attempt is made to repair it locally. If such an attempt is made,
the price of an exchange FRP is 100% the price of a new one.
Therefore, DO NOT ATTEMPT ANY REPAIR. To order Type 7521 as an FRP,
quote number FR0015.
1.5 Special Tools and Equipment
Type 2035 – Signal Analyzer Unit
Type 2816 – Multichannel Data Acquisition Unit or
Type 2825 – Acquisition Front-end
Type 1051 – Sine Generator (or similar)
– Frequency Counter
– Voltmeter
BZ5041 – Digital Hardware Test Program
BZ5076 – Analog Hardware Test Program
AO0370 – Cable for connection between Type 2816/
Type 2825 and Type 2035

Signal Analyzer Interface Unit Type 7521
Service Manual Brüel & Kjær
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Signal Analyzer Interface Unit Type 7521
Service Manual
BI5040–12e 2−1
Chapter 2
Service Note

Chapter 2 — Service Note
On-line Editions of the Service Manual
Signal Analyzer Interface Unit Type 7521
Service Manual Brüel & Kjær
2−2
2.1 On-line Editions of the Service Manual
Note: An on-line edition of a service manual is one that has not been published in printed
form. On-line manuals have the letter “e” appended to the literature number (“e”
denotes “electronic”).
From time to time some minor changes may be made to improve the performance
and serviceability of Type 7521. All information concerning these changes, or any
other changes to the service manual, are included in the latest version of the on-
line source document.
This Service Note section contains a history of the changes when any are made.
2.2 Printed Editions of the Service Manual
From time to time some minor changes may be made to improve the performance
and serviceability of Type 7521. All information concerning these changes, or any
other changes to the Service manual, will be released in the form of a Service Note.
Note: Printed Service Notes are renewed as a whole, meaning:
Discard the previous Service Note every time you receive a new one
The new edition of the Service Note must be placed in the binder in this section.
The organisation of the Service Note is as in the Service Manual, i.e. the Service
Note is divided into sections with names corresponding to the section name in the
Service Manual.

Signal Analyzer Interface Unit Type 7521
Service Manual
BI5040–12e 3−1
Chapter 3
Checking Procedure

Chapter 3 — Checking Procedure
Preparation
Signal Analyzer Interface Unit Type 7521
Service Manual Brüel & Kjær
3−2
3.1 Preparation
1. Connect the cable (AO0370) to Serial Interface 1 at the back of Type 2035,
and to Serial Interface at the back of the acquisition unit (Type 2816 or Type
2825).
2. Press Power "On" on both units.
3.2 Procedure
3.2.1 The Digital Part of the 7521
1. Insert Digital Hardware Test Program BZ5041 into the Type 2035 disc drive.
2. Press Reset while holding down Disc File Recall
3. The test program will be loaded in approximately one minute
4. Select K. 7521 Analyzer Interface no. 1to activate the test.
5. If after the test the monitor shows:
7521 Analyzer Interface - failed
Test ended 0001 error
the module must be replaced.
6. If on the other hand the monitor shows:
2816 Acquisition Unit - Verified
Test ended 000 errors
Then the digital part of the 7521 works within specifications.
7. To return to the usual analyzer setup, reboot the system:
— Insert the Analysis Software disk into the disk drive
—Press
Reset while holding down Disk File Recall
— Follow the instructions on the monitor

Chapter 3 — Checking Procedure
Procedure
Signal Analyzer Interface Unit Type 7521
Service Manual
BI5040–12e 3−3
3.2.2 The Analog Part of the 7521
Trigger Input
1. Press Power "On" on the Type 2035
2. Press Reset while holding down Field Entry 9
3. Move the cursor to Trigger: FREE RUN, using Field Select
4. Press Menu, select EXTERNAL, and press Menu
5. Connect a generator signal of 1kHz, 2.8Vpeak(126dBµV) to the Trigger Input.
6. Check that Triggered is written for a short while in the bottom left corner of
the monitor
7. Change the generator signal to 1kHz, 2.0Vpeak
8. Check that Triggered is not written in the bottom of the monitor
9. Check the supply voltage (found on BNT connector middle) for the Tacho probe
is 8.0 ±0.8 V.
Sampling Input
1. Move the cursor to the line under FREQ. SPAN, and an otherwise invisible line
will show.
2. Move the cursor to INT SAMPL
3. Press Menu, and select EXT SAMPL
4. Check that the curve has stopped moving
5. Connect a generator signal of 200kHz, 2.8Vpeak (126 dBµV), to the Sampling
Input/Output.
6. Press Measurement Start
7. Check that the curve is moving again
8. Change the generator signal to 200kHz, 2.0 Vpeak to the Sampling Input/Output.
9. Press Measurement Start
10. Check that the curve is not moving

Chapter 3 — Checking Procedure
Procedure
Signal Analyzer Interface Unit Type 7521
Service Manual Brüel & Kjær
3−4
Sampling Output
1. Press Reset while holding down Field Entry 9.
2. In the upper left corner of the monitor, change the Y scale from 80 dB to
160dB.
3. Press
Measurement Start
4. Check that the curve is moving
5. Connect the Sampling Input/Output to a frequency counter
6. Measure the frequency to equal 262144 ±13Hz.
Sync Input/Output
1. Press Reset while holding down Field Entry 9
2. Measure the Sync output on the guard ring of the Sampling Input/Output
connector with a Frequency counter to be 4.0 ±0.4Hz with a 3.8 ±0.4µs pulse
If any of the results differ from those given in this chapter, see Chapter 4.

Signal Analyzer Interface Unit Type 7521
Service Manual
BI5040–12e 4−1
Chapter 4
Adjustment Procedure

Chapter 4 — Adjustment Procedure
Introduction
Signal Analyzer Interface Unit Type 7521
Service Manual Brüel & Kjær
4−2
4.1 Introduction
The purpose of this procedure is to realign the trigger level for the Trigger Input,
and the trigger level and the delay for the Sampling Input if they do not fulfil the
specifications stated in Chapter 3.
Note: When adjusting the Delay, two Type 2816/2825 units and two Input Modules (Type
3015/Type 3019 or Type 3016/Type 3020) are necessary.
4.2 Preparation
1. Connect the cable (AO0370) to Serial Interface 1 at the back of Type 2035,
and to Serial Interface at the back of the acquisition unit (Type 2816 or Type
2825).
2. Press Power "On" on both units.
4.3 Procedure
4.3.1 The Trigger Input
1. Connect the Sine Generator to the Trigger Input on Type 7521
2. Select a generator signal of 1.0kHz, 118.6dBµV
3. Press Reset 2
4. Use the Type 2035 setup Fig.4.1
5. Press Start. The analyzer should just be able to trigger on the signal
6. If it does not just trigger, you must adjust it (steps 8 to 12):
7. Press Power "Off" on the acquisition unit.
8. Withdraw Type 7521, adjust P1 and return the module to slot 0.
9. Press Power "On" on the acquisition unit.
10. Press Reset 2
11. Press Start
12. Check that the analyzer just triggers, if not go back to step 8.

Chapter 4 — Adjustment Procedure
Procedure
Signal Analyzer Interface Unit Type 7521
Service Manual
BI5040–12e 4−3
4.3.2 The Sampling Input
1. Connect the Sine Generator to the Sampling Input on Type 7521.
2. Select a generator signal of 1.0kHz, 118.6dBµV.
3. Use the 2035 setup shown Fig.4.1.
4. The analyzer should just be able to make new a sample.
5. If it does not just make a new sample, you must adjust it (steps 6 to 11):
6. Press Power "Off" on the acquisition unit.
7. Withdraw Type 7521, adjust P3 and return the module to slot 0.
8. Press Power "On" on the acquisition unit.
9. Press Reset 2
10. Press Start
11. Check that the analyzer just makes a new sample, if not go back to step 6.
Fig.4.1The Type 2035 set-up required for testing the trigger

Chapter 4 — Adjustment Procedure
Procedure
Signal Analyzer Interface Unit Type 7521
Service Manual Brüel & Kjær
4−4
4.3.3 The Delay Adjustment
Adjustment of the delay is only necessary when two acquisition units are connected
to a Type 2035, since delay adjustment enables a complete phase match between
the sampling signal of two acquisition units.
1. Connect the interface cables to the Type 2035 and the two acquisition units
2. Press Power "On" on all three units
3. Connect Sampling Output on Unit 1 to Sampling Input on Unit 2
4. On the Type 2035 press System Setups twice, and then press Menu
5. Select 10 MULTICH. INPUT/OUTPUT DEF., and press Menu
6. Change the setup to the one shown below:
Input Sig: 1 X1
Input Signal No 1 1;1
Output Sig: 1 Y1
Output Signal No 1 2;1
Tacho: Off
Generators: 0
Max Frequency: 25.6kHz
7. Return the cursor to MULTICH. INPUT/OUTPUT DEF.
8. Press Menu
9. Select 12 MULTICH. CONDITIONING SETUP, and press Menu
10. Change the setup to the one shown below:
Slot 1;1: 800mv + Direct DC ¬OFF []
Slot 1;2:
Slot 1;3:
Slot 1;4:
Slot 1;5:
Slot 1;6:
Slot 1;7:
Slot 1;8:
Slot 1;1: 800mv + Direct DC ¬OFF []
Slot 1;2:
Slot 1;3:
11. Press System Setups twice
12. Change the setup to the one shown below:
Wm CROSS-SPEC X1,Y1 PHA UNW