820-3662 Audio sounds un-boosted/"tinny".

[SMMRepair]

820-3662 works beautifully, but the audio sounds like it's playing at 1/10th power. At max volume, you still have to be ~6 inches from the speaker to hear anything. In addition, it sounds like it's lacking any and all bass/mids (very tinny). I thought maybe there was a leaking or missing cap somewhere, but found nothing. Everything seems to measure properly, and there was no liquid damage. Super clean board.

Any ideas? All measurements I took in the audio circuit seem normal. All help appreciated--thanks!

 

[Therealkilometers]

Did you try different speakers? What about headphone jack?

 

[SMMRepair]

Yes, tried 3 different test assemblies, same symptoms. I believe the headphone jack works fine, but will check and confirm again to be sure.

 

[SMMRepair]

Headphone jack works fine, yes.

 

[dukefawks]

There are 4 amps, 2 for high tones and 2 for bass. The high tones seem to work. Look on the scope if there is any input to all 4 amps. The startup chime will go through the bass speakers so that is probably missing too.
Could also be low voltage to the analog section of U6201 or low voltage to the amps.

 

[SMMRepair]

Thanks, duke. Will check on that. And yes, the unit does chime but it's very, very low (same as volume in OS). Thanks!