Problem with amp

[RobPhill33]

I built a power amp about 2 years ago and it has worked fine (casual use) until the other day the right channel started crackling with no pre-amp attached. None of the caps are getting warm, all the voltages on the board are fine. However, the DC offset is much smaller (4-5mV) for the crackling channel than for the left (45mV). Before I start replacing the output devices ($$) is there anything else that it could be??

[djmiddelkoop]

While it's difficult to troubleshoot without schematics, I can only speak with experience.
I would check the input first. This is mostly a differential stage which also takes care of the output offset.
Try with "Freezer" to make it cold and see what it does.

For Freezer look at the local Radio Shack or electronic store.

Dick.

[slowhands]

Originally posted by djmiddelkoop
While it's difficult to troubleshoot without schematics, I can only speak with experience.
I would check the input first. This is mostly a differential stage which also takes care of the output offset.
Try with "Freezer" to make it cold and see what it does.

For Freezer look at the local Radio Shack or electronic store.

Dick.

It is indeed difficult to guess what is wrong without schematics or the actual unit. I agree the differential pair could be faulty. In my experience, it is possibly more likely that the input cap is faulty. I'd certainly check both areas. Your idea of using freeze spray is a good one too.