CA2000 intermittent crackling

[ropetrick]

Hi,

Restoring a CA2000 and the re-capping is complete. The 2SA798 transistors were replaced with KSA992.

There is an intermittent crackling noise on the left channel from the board F-2573. We can't seem to nail where it is from but have a few clues. The transistor TR01 (left channel) gets warm. Have tried swapping with TR02 from the right channel but now the swapped transistor gets warm, so that rules out the transistors. Or does it not ?

What do you think the problem could be ? Have attached a portion of the schematic from board F-2573.

Any help would be grateful. Cheers.

 

[ropetrick]

Could it be the preceding resistor R23 ~ 22K ?

 

[Hyperion]

Have you checked the voltage on the collector of that transistor....? are the +/-32V supplies ok? - presumably a regulated supply? - regulators working ok?

 

[ropetrick]

Thanks John. Its late here. Will do first thing tomorrow.