Denon PMA-700AE Amplifier Repair



Fault
Amplifier would not power up.

Internal inspection identified a number of issues.
F101 Power input protection fuse open circuit.

R220,R219,R222,R221 220 ohm resistors burnt up. (Black)

IC203 TC9164 Cracked.

The first step in repairing the Amplifier was to replace the failed parts, Fuse replaced T2.5 Amp.

Failed resistors also replaced, and IC203 TC9164N, TC9163N removed..

Further checks made, TR517 2SD2083, TR519 2SB1383 Left channel Audio Output Transistors short circuit.
ZD501 2V7 500mW Zener Diode & D509 ISS70A 500mW short circuit.

Defective parts replaced, and Amplifier powered up.

Bias for each channel set.

Further checks made, plus & minus 15 V supplies very high at 41 volts.

TR101 2SD1913 & TR102 2SB1274 Short circuit.

Both transistors replaced, restoring the 15 volt supply lines to normal.

IC203 & IC202 replaced.

The 15 volt supplies also power the tone unit.
(Front Panel Mounted PCB)

IC301 NJM2068 dual channel op Amp replaced
Also C309 100uF25 V, C310 100uF 25V.

Amplifier fully tested correct operation

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