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Arcam Diva P80 Power Amplifier Repair



Published
Fault
Amplifier switching to protection mode no Audio output.

The service manual for the P80 provides a detailed circuit description.

Under normal operation the Amplifier power LED should turn solid green and then the Speaker outputs can be selected SP1 /SP2.

When protection circuits operate, the first action is to determine if its being triggered by an actual fault or an issue with the protection circuit itself.

IC603 HT48R30A-1 Micro processor monitors the status of the protection circuit.

Pin 28 DC Offset, Pin 27 VI Lim, both pins were checked and pin 28 was high at 4.8 Volts.

The DC levels entering the protection circuit was checked, left channel R634 & R635 Right channel both were low at a few millivolts.

Hence the fault was due to failure of the protection circuit.

Checks carried out and TR608 FMMT497, TR605 FMMT597 short circuit, both transistors replaced fixing the protection fault.

Due to the age of the Amplifier the main board was checked for dry solder joints.

Speaker terminals re-flowed.

Speaker protection relays replaced as shown in the video.
Omron G5Z-2A 24 V DC 03Z2CC

Bias for each channel checked no adjustment required.

Amplifier fully tested working correctly.
Category
Audio
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