Aion Solstice (Shredmaster) Help

[jmasciswannabe]

This one has me stumped. The voltages on the ICs are right, grounds check out and bias points all check out. The issue is feedback/oscillation/motorboating on output. Volume control does not totally negate sound on one end. I know it doesnt go to ground, but should there be signal on both sides?

I've double checked all resistors and caps and parts are right. I even found where R5 on the parts list should be 10k instead of 1k, but that did not fix the problem. Verified pots are right. Swapped out ICs, too.

Here is the link to the pdf doc:
https://aionelectronics.com/project/solstice-marshall-shredmaster-distortion/

Any input on this would be greatly appreciated. I am going a bit crazy. Ha!

[smackoj]

Hi; I have a few suggestion for you to try: Check all solder joints. If you are using a battery, check it for voltage loss when in use. Try moving your ground points around. I ave built a few Aion pcbs and I remember having to experiment with the grounding before they would
pass the signal. Test the diode to make sure it is is the correct part and that it tests as working good.

Good luck.  Jack D

[jmasciswannabe]

Already reflowed all joints. Using AC. Will verify all ground points again. Dont think it is a diode issue as voltages check out. Thanks for suggestions!

[jmasciswannabe]

...1uf on the electro off the bias, instead of 10. Ughh! At least I can go to sleep not obsessing! Maybe this might be of help to someone in the future.

[aion]

That would definitely do it. I've experienced similar things with other medium-to-high gain circuits where they'd oscillate if the Vbias filtering wasn't good enough.

[jmasciswannabe]

FWIW, 10uf worked, but 100uf worked even better.

[PRR]

yesterday> I've double checked all ...caps ...are right.
today> ...1uf ....instead of 10. Ughh!

Which is why we never believe "all parts right". Sorry, but everybody is human. Or: don't trust anybody over/under 30?

> 10uf worked, but 100uf worked even better.

That was my reading. There is a LOT of low-impedance stuff referencing Vbias, including the output and the input. So slamming signal at the output sneaks-back through Vbias into the input, causing stray paths which may cancel, not-cancel, or feed back. 10u may clamp enough to avoid trouble, but seems marginal to my eye. 100u seems ample, again without actually studying what is going on.

[jmasciswannabe]

Human, indeed. Thanks for the explanation on why it was happening! Considered measuring components before installing as several fellas do, but where is the fun in that?