First pedal issue (Fuzz face)

[James89]

Hi all, I was wondering if someone on here could help with an an issue I'm having with a fuzz face breadboard project.
I have gone by the NPN schematic on this site - https://fuzzcentral.ssguitar.com/fuzzface.php
The issue I'm having is I get almost zero volume. I'm using BC108C for Q1 & Q2. The only difference I have to the schematic is I am using 2 resistors in series for the 8.2k (adding to only 8k as I couldn't find an 8.2). I'm also powering it with a 9v adaptor.

Can anyone tell me where I should first look for issues (beyond checking it's wired correctly, as I've rebuilt 5-6 times and followed the schematic exactly each time with the same results)?

Thanks!

[bushidov]

Well, this could be a few things. Firstly, check the pinout of the BC108C's for what pins are E B and C. Standards exist, but are not always followed as to what thing is what on what footprint.

Second would be line testing.

1. Take the line on your breadboard that goes from your out jack where it connects to the middle pin on the volume pot and print it over to the 2.2uF cap. Strum. Should get a clean sound noise. I typically just do this as a "sanity check" as it should at least make a level noise.

2. If that worked, then move over to the collector of Q1 and the 33K resistor. Strum. You should get a louder noise here (Q1 is amplifying)

3. If that worked, then move over to the collector of Q2 and the 8K resistor. As that is a picky bias resistor, the 8.2K is something you want to strive for, but it should be close enough to at least make a little noise. If you have a 10K trim-pot, that might work better for you. Anyways, strum. You should get a fuzzy noise at this point

4. If that worked, then move over to where the 8K, 330 ohm, and 10nF cap all intersect. Strum again. Sound should be similar as in 3.

5. If that worked, then move over to pin 3 of your volume knob. Make sure volume knob is all the way up. Strum. Sound should be similar to 3 and 4.

6. If you got this far and everything is working, then your volume pot is either wonky, or now everything is just working.

I'd be curious where the problem occurred for you.

[smallbearelec]

Are you sure that your input and output jacks are wired correctly? There are some pictures in this article:

http://diy.smallbearelec.com/HowTos/BreadboardSiFF/BreadboardSiFF.htm

that might help you nail the problem.

[James89]

Thanks for the prompt responses!
I've checked the jack sockets and both are good.
I've also checked the first cap. This worked but only when connected just through this. What I mean is, because I had the base of Q1 connected to that row also it seemed to prevent any signal going through. I then connected the input to the cap and then output on another section of the breadboard and it worked fine.
Given that I wasn't actually running through Q1 in my first attempt through the cap, is it possible that the +9v is playing havock? I've tried another power supply and got the same results.

[MaxPower]

Do you have a multi-meter? Measure the voltages at the emitter, base, and collector of each transistor. A picture of your breadboard would help.

[James89]

I've disconnected everything other than the first cap, q1 and the 33k resistor.
The 33k is going to +9v. The black wires and all ground and the other red wires are input and output.
I don't currently have a dmm but should have one by the weekend.

[bluebunny]

I don't currently have a dmm but should have one by the weekend.

That's good.  You'll find it invaluable: not just for this pedal, but for the second one, and the third one, and . . .  (You ain't getting out of here alive!  )

[antonis]

(You ain't getting out of here alive!  )

..said by honoured member of DMM batteries recycle club..

[MaxPower]

Doesn't look like you have the 100k resistor connected to the base? If not, try connecting the 100k resistor from the base to ground and check if you get audio out at the collector.