I've been working on a big muff from diyguitarpedals.com.au and am not getting any sound. I've audio probed it and am getting sound to C12 to the base of Q4 but not c13. I've replaced c13 and have the same issue. I've reflowed solder as well around that whole section to no avail.
I don't get sound to any other pin than the base of Q4. Should I be getting sound to either of those pins?
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If you're getting signal to the base of Q4, then the problem lies with R21, R22 or Q4. Make sure solder connections and PCB traces are good in that area of the circuit. Also make sure Q4 is oriented the correct way in the PCB
Can you post pictures of the board? That is alway a good place to start.
Quote from: danfrank on October 07, 2020, 02:30:14 PM
If you're getting signal to the base of Q4, then the problem lies with R21, R22 or Q4.
Agreed! Make sure your resistor values are correct. Also make sure you used the correct transistor for Q4 (make sure you didn't accidentally install the wrong part number)
Q4 is in there the right way. Replaced r22 last night. Transistor is socketed so I tried others and that's a no go. I'll try reflowing those pins, replace r21 and report back.
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Replaced R19 and I've got sound now. It's not very loud or fuzzy. I checked that the resistors in the output buffer that lead to 9v are getting it R20 and R21) and R19 and 22 are getting a good connection to ground. It looks like this stage is supposed to get the volume back but that doesn't seem to be the case. I did check that all resistors that should be getting 9v are. I guess I'll check the grounds next? Does that seem logical?
Edit: posted a video below. All knobs dimed.
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https://youtu.be/HAA0_tKjkZM