Aion builds oscillating

[Ry]

I've just wired up 5 Aion builds and find that they all oscillate with slight gain or volume. I've built a bunch of Aion boards in the past without this issue, but these all have the same issue. They are: Argent, Andromeda, Binary, Aurum, and Heliodor.

It is possible that I have a bad batch of some common component, but I've been using the same parts stash for a couple dozen builds by other board makers (Madbean, Defx, and PedalPcb) without any issues.  I tried switching out power supplies, amps, and guitars with no improvement.

Here's a link to one of the project files for reference:

https://aionfx.com/app/files/docs/andromeda_documentation.pdf

Any advice would be appreciated!

[PRR]

Layout. No box. Grounding. Bad cords.

[ElectricDruid]

+1 agree with Paul. I seriously doubt this is a "Aion PCBs" problem, despite you apparently not having had similar trouble with other boards (yet?). I'd be thinking about what might have changed in your test rig set-up recently and seeing if there isn't something there that explains a sudden outbreak of oscillation with everything you plug into it.

HTH

[Ry]

I hear ya.  I thought the issue would resolve when I boxed them up.  I did build a BF-2 from pedalpcb in the same run, and it's fine.  I'm not new to this by any means, I just returned to building after a solid 10 year break after we got the Ludwig Phase II project up and running.  I've put together about 150 builds during the pandemic.  I've never had more than one oddball issue due to user error in a run, which is what makes me suspect something different in these layouts.

Looking at the new Aion schematics, he seems to have dropped the series 100R resistor in the power supply filtering for these new board.  I'll tack that in and see if it helps anything.  Fingers crossed.

[GGBB]

Are you using the Aion "bypass board"? If not, the 100nF power filter cap and the reverse polarity protecting Vin diode (which you could sub out for the 100R if you preferred) are absent. But to be clear, are we talking about runaway oscillation/squeal, or just noise?

[Ry]

I'm using the board that comes with the pcb...that snaps off with the switch soldered to it.  The issue is runaway oscillations when gain or volume are increased...which leads me to suspect that the power supply might be oscillating and is amplified by the gain and volume. It sounds like the effect is probably working under the squealing.  The only thing I did differently was to use mlcc caps for the 100nf power filtering.  I may try a film one instead, just to see if it helps.  Adding the 100r resistor in line did nothing.

[Ry]

Well I have to say that no matter how many pedals I've built, I can still find a new and exciting way to screw up.  I had the sleeve and tip swapped on my jacks. 

The builds sound great, of course.

[ElectricDruid]

Well I have to say that no matter how many pedals I've built, I can still find a new and exciting way to screw up.

We can all identify with that! Only *too* well!

Glad you got it sorted and it wasn't a difficult fix.