Phase Linear 700 S2 Service Manual

Page 1

700 SERIES TWO
POWER AMPLIFIER

I
41:3?

Page 2

700 SERIES TWO POWER AMPLIFIER

SERVICE MANUAL

CONTENTS

l-O. Technical Specifications

2-0. Schematics and Diagrams

3-0. Circuit Descriptions 12
4-0. Disassembly Procedure 14
5-0. Test Procedure 17
6-0. Troubleshooting Guide 19
7-0. Parts List 25
8-0. Service Bulletins and Supplements 26

*****k********k**k*****CAUTION************k***********

THIS MANUAL IS INTENDED FOR USE ONLY BY QUALIFIED TECH-
NICAL SERVICE PERSONNEL. HAZARDOUS VOLTAGES MAY BE
ENCOUNTERED IN THE TEST AND SERVICING OF THE 700 SERIES

TWO. USE EXTREME CAUTION: READ ALL INSTRUCTIONS CAREFULLY.

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6-4.

6-5.

6-6.

OUTPUT MALFUNCTION INTO A LOAD

6-4.1.

6-4.2.

Unit will not deliver 53 V RMS into 8 ohm load.

a) Check for line or variac voltage sag; voltage
at the line plug must be at least 117 VAC when
delivering full output.

b) Possible defective output transistor or driver;
perform step 6-1.4.

Asymmetrical clipping (or loss of half of wave form).

a) Check protection circuit as outlined in step 6-3.3.

b) Check for balanced power supply voltage at the
main filter capacitors while driving a load. If
voltages differ by more than 2 volts, replace the
capacitor which reads low.

c) Check for defective emitter resistors; perform
6-1.4.

EXCESSIVE DISTORTION

6-5.1.

6-5.3.

Improper bias setting. Check and adjust as follows:

a) Allow at least 5 minutes warm-up time; perform
step 5-4. to accelerate warm-up.

b) Remove all input and output connections, then
measure the DC voltage drop across R109 located
in the output stage.

c) Verify a reading of no less than 0.30 VDC and no
greater than 0.45 VDC. Adjust R107 as necessary.

THD analyzer adjustments.

a) Activate the 80K Hz filter on the analyzer if it
is so equipped and repeat THD measurement.

b) Examine test bench grounding system for possible
ground loops. Ground the analyzer directly to
the 700 output ground, not to the load, scope
or meter grounds. Use 16 guage wire for output
ground system.

Defective protection circuit. Refer to 6n3.3.a),b).

EXCESSIVE OFFSET

a) Replace Z101.
b) Verify +15 VDC :10% across Dl; replace if necessary.
c) Verify -15 VDC :10% across D2; replace if necessary.

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