Thermionic Distortion Build Troubleshooting

BoloTieBandit

New member
Finished soldering everything up on the Thermionic PCB, but upon plugging it in, I get a loud buzzing sound, the “top” LED doesn’t turn on, and only two of the LEDs on the back (left ones shown in picture) are turning on.

I checked as many of the solder joints as I could and they all look fine to me. Kinda just wanna get an idea of where to start troubleshooting this. Any ideas? 1841A03A-D756-4CEB-B5C0-A16AFDC85834.jpeg
 

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Looks like your op amps aren’t socketed so there could be an issue to one of those if they received too much heat. Do you have a DMM to check voltages?

In a build with problems, it is best practice to clean the board with IPA to make sure there isn’t any flux that is causing a short.

If the op amps are okay, check all of your values. If they are correct then try to make an audio probe to trace the signal. Loads of info on this forum or online.
 
It still like your input and output are wired incorrectly.

The long springy bit that touches the tip of the 1/4" plug is what connects to the switch daughter board, it looks like you have those connected to the ground buss on the PCB.

Typically, Tip= signal, ring=ground.

As for the LEDs, have you double checked polarity on those? It's real easy to get them backwards, PedalPCB does it the "correct" way, but the correct way can seem a little counter-intuitive. The short lead on an LED goes to the square pad, the long lead goes to the round pad. The positive lands on A(node) and negative lands on K(athode...cathode. not sure why it's a K).

Also, take a look at your wire-to-board connections. It looks like you're using a non-prebond-stranded wire; It's the stuff that I typically prefer to use honestly, but it has a tendency of fraying out and causing shorts on either side of the PCB.

I'd recommend cutting off the excess from the terminated side, and cleaning up any strands that might have gone astray. All it takes is one strand, thinner than a hair, to cause a short. They can be difficult to see...headband magnifiers are hugely helpful in this case.

If none of that helps, post your opamp voltages, that can help narrow down where the problem is.
 
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