Chop Shop - No Sound When Effect Engaged

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Davemulls

Member
Hey guys hoping I could get a bit of help on a Chop Shop build I'm working on. When bypassed everything works as it should, but when the effect is engaged I get the LED turning on but no sound passing. After doing some probing along the signal path I've found that I have signal on the gate of Q1, but nothing past that. I measured the voltages and I have for Q1 Gate: 0v Source: 0.8 Drain: 4.5

Any ideas? Sorry for the rat's nest. I'm adapting this to fit an enclosure that was already drilled so there are a lot of wires.
 

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Hey Neil ya this was posted to Reddit as well. The jumper isn’t touching the foot switch lug, it’s just the angle of the photo.

I ended up replacing Q1 as I suspected it was fried and I have the signal passing now, with mostly expected behaviour. The weird thing is I have to have Q2 biased at like 0.1 V for the signal to pass, and the distortion is a very ugly type that doesn’t sound like what’s expected. So I’m still looking for a solution but now it’s for a new problem 😂
 
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I knew I had seen it somewhere. Glad you have it partly going.

I have three things I would look at:
  1. C5. Is it definitely 22uf? Or is it a 2u2?
  2. C6, c7 and c10. What is the code on them? They should say 105. They look smaller than the 1uf caps I use.
  3. What is the code on q3? Is it a PN2222 or a 2n2222? If it is the latter then I think you have it in backwards.
 
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Davemulls said:
If the code says JCPN2222AR27 that would mean the orientation is correct though right?
Click to expand...
yes, it should be. that P is the important signifier; I think it originally meant that it was in a plastic, as opposed too metal, housing, but that's by memory, which I truly don't trust... There must be a rational reason why the pinout was reversed.
 
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Davemulls said:
Hey Neil:

1. Confirmed 22uf
2. Confirmed they say 105
3. Code is JCPN2222AR27 so I believe that is correct?
Click to expand...
Awesome, that all looks good then.

Nothing stands out to me as being obviously wrong. I looked at your resistors and they look like the right values.


Have you tried resoldering everything? I had an electro cap recently that looked soldered in but actually had one leg floating which caused the whole thing not to work.
 
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neiltheseal said:
Awesome, that all looks good then.

Nothing stands out to me as being obviously wrong. I looked at your resistors and they look like the right values.


Have you tried resoldering everything? I had an electro cap recently that looked soldered in but actually had one leg floating which caused the whole thing not to work.
Click to expand...
Thanks for taking the time to look through! I haven’t resoldered yet so that will be my next step. I’ll post here when I have
 
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