Spirit Box Oscillation Issue

[Briks]

My Spirit Box powers on and passes signal though when I have the depth knob raised anywhere below 0 I get a nasty oscillation that worsens the more i turn it up. I’ve checked my values and connections, everything seems to be ok. Please let me know what the issue may be or what info you’d need to assess the problem.

 

[Reno315]

Check R8 to see if it is 22k, and check to make sure your dwell potentiometer is B5k. I recently built this board and played around with different values there to make is self ocillate. I don't know if this will help but it will give you a place to start following the schematic around. When in a jam I use an audio probe too.

 

[Briks]

So I built my first audio probe as I’m still new to this. At first the oscillation began at R9, I switched it out which stopped it. Then it happened again at R13, which I also switched out and the oscillation persisted. Since the issue didn’t occur at IC1, and happened before the pt2399, I’m stumped.

 

[Reno315]

Sounds like a wrong component value or solder joint perhaps. I'm pretty new to this as well, and can still make those mistakes. Check all components to the build documents after you try reflowing the board. If you can post a pick of your board I can compare it mine and see if anything sticks out.

 

[Chuck D. Bones]

Inspect first, then reflow only if necessary. Otherwise, you risk creating new problems.

 

[Briks]

I double checked the components and had to switch out a few incorrect resistors. I also reflowed a few suspect solder joints. Still have the same issue. It happens at R13 then every connection from there. Here are some photos (took the Belton off on one to assess those joints). I appreciate all the help!

 

[Briks]

Update...I changed out the pt2399 just in case. Still having the same issue.

 

[Nostradoomus]

Can you take a better resolution picture of your component side? I don’t see any red stripes where there should be (10k resistors etc) from that picture but it could just be the focus

 

[Briks]

Let me know if this works!

 

[twebb6778]

I'd definitely recommend giving your board a clean with some isopropyl, it looks pretty grimy.

Probably won't solve your problems, but it's a good habit to get into.

 

[music6000]

Need to confirm R19, R6, R102 values are correct
Confirm Pot Values are correct & match the PCB.
As recommended above, I'd definitely recommend giving your board a clean with some isopropyl, it looks pretty grimy.

 

[Nostradoomus]

Did you happen to use a different value for the dwell potentiometer? The oscillation mod for this involves lowering R8 and raising the dwell pot to 25k so something in that area is most likely the issue.

 

[music6000]

Let me know if this works!View attachment 3476

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