Sandspur fuzz - no sound, led and bypass work

[Jedijedd]

Hello all,
This is my first post here, and probably like many new members, I have a troubleshooting question as my first post. I put together a Sandspur fuzz and have been getting no sound from the pedal. I get signal in bypass and the led works but nothing from the pedal itself. Interestingly enough, it produced sound on my first try, but the led was very weak and so was the sound. I’m not sure if there is a grounding issue or something is wired wrong.

Some of the troubleshooting things I have tried:
- tested all the values of caps and transistors which seem fine.
- tested the sweep and value of the pots which seem fine.
- tested the input jacks and footswitch
- tried different transistors with no change
- checked that I haven’t switched the input and output cables
- checked for grounding issues such as cold solder joints, bad solder joints, or bridges (I know some of this is not the prettiest but I’ve done the tug test and continuity test, however I could be testing these things wrong?)
-I replaced C3 with a new cap, as I wasn’t getting a reading but nothing has changed
- checked for any grounding issues such as metal touching the enclosure or foot switch

Things I haven’t tried or been able to figure out:
- getting correct measurements from the diode (I get a reading one way but not the other) or the electro caps. I haven’t removed them yet to get correct readings. I get values but they seem all over the place
- I haven’t been able to bias the transistors yet

I also wasn’t sure about my power supply. I have two wall warts that are center negative but one says ac/dc adaptor while the other says simply “dc”. I grabbed one thinking it was the dc one and wasn’t sure if I fried anything.

Anyway, I have been trying to get this to work for a few weeks, while also taking my time with it. This is my second pedal I’ve built, and the other one had the wrong value cap keeping it from working. I’m sure I am missing something simple here and hoped that another set (or sets) of eyes could help.

Thanks for looking and reading!

 

[Jedijedd]

Did we ever get collector voltage readings?…

If I’m reading these right Q1 is 0.89 at the collector and Q2 is 0.24. This is with the multimeter set at 20 at the dc volt setting. I put the negative probe on the negative power input.

 

[Jedijedd]

Make sure you’re probing the correct pin. Pin 3 isn’t connected to anything which then makes the trimmer a variable resistor. Check C1. If you’ve got no signal going in there, then the trimmer is your problem. It’s most likely a bad solder joint.

I’ve checked c1 and am getting no sound with the probe. I might try reflowing the solder later today. The joints look fine but I might be unable to see without a magnifying glass.

 

[Harry Klippton]

If I’m reading these right Q1 is 0.89 at the collector and Q2 is 0.24. This is with the multimeter set at 20 at the dc volt setting. I put the negative probe on the negative power input.

That doesn't sound right at all

 

[Jedijedd]

That doesn't sound right at all

That doesn’t sound right as in I’m taking the readings incorrectly or something is up with the transistors?

 

[BuddytheReow]

Your collector voltages are off. Have you confirmed that 9v are going into the circuit? You can confirm that for this circuit by testing both sides of D1. There will be a slight voltage drop. If they aren't close to 9v there's an issue.

 

[Jedijedd]

Okay I'll test this and report back. Thanks for the help all!

 

[Harry Klippton]

That doesn’t sound right as in I’m taking the readings incorrectly or something is up with the transistors?

It's hard to say. Either you're reading them wrong or your circuit is really really off