aionelectronics Comet troubles

[derryckw]

Im having some troubles with this comet build and can't seem to find the problem.  When I hit a note I get a static distortion sound, I turn the distortion to 0 and put the clipping in diode lift and I still get it, so I swapped out the IC, no help, then I swapped out the IC socket, no help, the static is not present at R23 or pin 5 of the IC but when you go to pin 6 it's there.  I swapped out R23 for a higher value but that made no difference either.  I am getting the static on R9 and C5 which is making me think I might have a bad POT, any thoughts before I rip this POT out??

Thanks all,

[Kipper4]

Check R8 for bad connection maybe.
I suspect the IC1 op amp is misbiased. And that's the "static" your hearing.
I have been known t be wrong though.

[PRR]

Welcome.

As you know, you can't "see" what the electrons are doing.

You have a signal tracer, a good tool.

You should also have a volt meter. When the audio is mangled, one popular reason is bad DC voltages on amplifier stages, Kipper's "bias". At extremes, it does horrible things to nice sounds.

[derryckw]

R8 doesn't seem to be the problem although I reflowed solder again, getting 4.5v on R8 and 9V everywhere I should.  Pin 1 of the opamp I have 2.2v then 9v on the other side of R24.  Signal is now cutting in and out now, just sounds and feels like the IC combined with a bad solder joint, I've reflowed solder at every connection, double checked each component that I didn't throw a 100R into a 100k slot or something stupid like that.  I've chopsticked the circuit pretty hard and nothing stands out, still have a good signal flowing into the IC and crap coming out so it's definitely in that area.  Swapped the socket again just to eliminate and tried a few different ICs, almost time to give up it's taking to much of my time!

[Kipper4]

post your voltages for ic's please

[derryckw]

JRC4558
1-2.3
2-swings from 4.4 down
3-4.47
4-0
5-4.4
6-4.47
7-4.47
8-8.96