Linear Power 1502IQ distortion at low volume

[0ldSch00lf00l]

I purchased a Linear Power 1502IQ off of fleabay to be all nostalgic and what not and it seems to have issues. When I first powered it up, the right channel kept cutting out. I have not been able to repeat the right channel cutting out, but now I have another odd issue and that is distortion at low volume. Oddly, when the volume is at 1 or 2 on my Alpine CDA-9885, I get distortion in the midrange frequencies from the right channel. As the volume goes up, the distortion seems to clean up.

I was just wondering if anyone had any ideas before I send this amp to Ray at TIPS.

Oh, one more thing I will mention is that it appears that this amp was repaired, possibly not by TIPS because the solder on a few resistors seems to be new. Is it possible that the components were not matched properly and I have a bias issue or does the distortion tend to point towards bad transistors?

 

[Perry Babin]

I'd suspect the small electrolytic capacitors in the audio section of the amp. They are more critical in the old Linear amps than in other amps and when they fail, it can cause the audio to be distorted.

The 33uf caps have been the most common to fail in the Linear amps like the 1502 that I've repaired.

 

[0ldSch00lf00l]

Thanks Perry! I guess I can always start out by replacing the capacitors, and if that fixes the problem, it will be a more cost effective fix. I have a good friend of mine with a masters in electrical engineering who owes me a favor, so I may get him to replace the caps and get some use out of his fancy soldering station that he keeps bragging to me about😀