Crest Audio 7001 Service Manual

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SSCRESIALJDIO

4601 Professional Power Amplifier

Clip/Limit 88mm
Signal

Temp/DC
Active

Professional Series
Power Amplifiers

3301
4601
4801
6001
7001

Service Manual

CREST AUDIO lNC., 100 Eisenhower Drive, Paramus, New Jersey 07652 USA
T (201) 909-8700 FAX (201) 909-8666

CREST AUDIO EU ROPE, 5a Wilbury Grove, Hove, East Sussex BN3 SJQ England
T44+(0)273-325840 FAX 44+(0)273~775462

CREST AUDIO ASlA., 6001 Beach Road #17-03, Golden Mile Tower, Singapore 0719
fi65+(0)295-2328 FAX 65+(0)295-47D7

Release 1.1 4/93 Domestic

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lb |>

the user manual.

This symbol, a lightning flash with arrowhead within an equilateral triangle, appears on the
amplifier chassis to warn the user that uninsulated dangerous voltaggggge present within the
enclosure that may pose a risk of electric shock. "

This symbol, an exclamation point within an equilateral triangle, appears on the amplifier
chassis to warn the user to follow important operating procedures and precautions detailed in

This manual and the procedures detailed within are intended for qualified technicians
only! There are potentially lethal voltages present within an audio power amplifier, and it
is the responsibility of the technician to exercise common safety practices to protect him-

self, his co-workers, and the end user.

In particular, always exercise caution when working on an amplifier with the chassis
cover removed. Do not leave it unattended while it is connected to the Ac mains. Never
expose the amplifier or your test equipment to rain or moisture, and never work on an am-
plifier while you are standing in, sitting in or othenlvise in contact with, rain or moisture.
Before starting any repair or troubleshooting procedure, read and understand completely
the instructions for the procedure.

1 INTRODUCTION

#

This service manual includes tests, calibrations, schematics, a full parts list/order form, and troubleshoot-
ing tips to assist you in the repair and maintenance of Crest Audio Pro series 3301, 4601, 4801, 6001, and

7001 amplifiers.

The first step in troubleshooting is to identify the symptom. The next step is a complete visual inspection.
You may isolate the problem, trace it to a module, and swap it with a good module or continue trou-
bleshooting down to component level. If you follow this manual step-by-step it will be that easy. Good

luck!
Identify Visual Isolate Replace or
Symptoms Inspection Problem Troubleshoot

Glossary

Following is a list of terminology used in this manual.
Board A printed circuit board, or PCB.
Chassis The steel case or frame in which the modules, transformer, etc. are mounted.
Harness This term refers to all the wires, as a whole, which interconnect the boards carrying

specific voltages, signals etc.

Crest Audio Professional Series Power Amplifiers Page 1-1

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3 FLOWCHARTS FOR TROUBLESHOOTING

Flowchart A. Problem: No Sound

Yes
Are active LEDs on?

Is volume control up?

Check input
& output
connections.

Are Temp/DC LEDs on?

Ahahl Adjust
the volume
control.

The channel is in
protect. Disconnect all
inputs & outputs. See
Troubleshooting,
Chapter 4,

M if the problem

remains, see
Troubleshooting,
Chapter 4.

See Flowchart C

Flowchart B. Non Functioning Fan

See Troubleshooting the Rest
of the Amplifier; Chapter 6.

CrestAudio Professional Series Power Amplifiers Page 3-]

Service Manual Release 1.1 4/93