How to get rid of this high pitch oscillation in a fuzz face?

[henryd]

Hey guys, I built a silicon fuzz face with nos components on a pigeon fx pcb trying to replicate it as close as possible to an original. I got it to work but there is this high pitch sizzle when all controls are on max. I breadboarded the exact circuit out with similar nos components, and there is no high pitch noise on that at all. I did swap out the tfk bc108c transistors for others on the pigeon pcb but it didn't change it. Is there something that I'm missing? all of the resistors look to be close enough values on my multimeter.

The first half is the pigeon pcb with the noise and second half is the breadboard which sounds find:
Link to soundcloud

 

[Bio77]

Maybe power supply. Is your breadboard one of the PPCB ones with the power filtering?

 

[henryd]

Maybe power supply. Is your breadboard one of the PPCB ones with the power filtering?

The breadboard is just a basic one without power filtering, also I tried multiple 9v batteries on the fuzz face without any change to the noise.

 

[Bio77]

Next guess would be bad cap. Try audio probing through the circuit to find out where the noise starts.

 

[Harry Klippton]

Let's see some pics

 

[henryd]

Let's see some pics

I originally had a 8.2k resistor where the trimmer is as well. I had it in it's enclosure but took it out for troubleshooting.

 

[Coda]

Try a 47p cap between the collector and base of Q2…

 

[henryd]

Hey guys so I have an update on the fuzz face. I removed all of the components from the board including the pots and breadboarded it to see if the problem would persist on the breadboard. It ended up sounding amazing with no hiss or any problems. So the problem is something to do with the pigeon fx board or the wiring. Anyone know what is causing it then?

 

[Robert]

If you're using the exact same components with the exact same schematic but the PCB oscillates and the breadboard doesn't then it's likely trace routing/proximity of components or the long offboard wiring.

 

[henryd]

If you're using the exact same components with the exact same schematic but the PCB oscillates and the breadboard doesn't then it's likely trace routing/proximity of components or the long offboard wiring.

The funny thing is I used similar nos components on another pigeon fx pcb that had no oscillation but that one was germanium. Only other difference I can think of is two of the capacitors on the germanium one had difference volts ratings but the same uF value.

 

[Big Monk]

What are your voltages?

Are your power supplies different from breadboard to pedalboard?

 

[henryd]

What are your voltages?

Are your power supplies different from breadboard to pedalboard?

I'll check my voltages soon, and the power for both breadboard and pedalboard was a carbon zinc Greencell 9v battery. Do you think the pcb is at fault?

 

[Big Monk]

I'll check my voltages soon, and the power for both breadboard and pedalboard was a carbon zinc Greencell 9v battery. Do you think the pcb is at fault?

These things can be hard to diagnose.

Are you using the big round enclosure?

 

[henryd]

These things can be hard to diagnose.

Are you using the big round enclosure?

Yeah I have the original big enclosure. I did try it in the enclosure attached to grounding screw, and tried it out side of the enclosure, which didn't change anything.

 

[Big Monk]

Yeah I have the original big enclosure. I did try it in the enclosure attached to grounding screw, and tried it out side of the enclosure, which didn't change anything.

Same settings between the breadboard and enclosure? And same components, right?

 

[henryd]

Same settings between the breadboard and enclosure? And same components, right?

Yeah I maxed out the volume and fuzz pots on both. All same components, only difference is no footswitch on the breadboard. I'm thinking it might be a defect in the tracing in the pcb? Here is the breadboard btw.

 

[Big Monk]

Yeah I maxed out the volume and fuzz pots on both. All same components, only difference is no footswitch on the breadboard. I'm thinking it might be a defect in the tracing in the pcb? Here is the breadboard btw.View attachment 62225

Well, the boards ARE different (vintage vs. Pigeon) bit I’m not sure in any consequential way:




It looks like the Pigeon board just switched the collector resistors and the voltage divider string around a bit.

I think a more likely culprit is how the wires are spaced apart on the breadboard vs. the bundled cable approach of the OG.

You could try some shielded wire on the I/O.

 

[henryd]

I got another update. So I detached the pcb from the circuit and connected it to the jacks and pots without the dpdt. I unplugged and plugged back in all of the wires one at a time with none of them recreating this buzzy high pitch oscillation except for one. The wire that connects the negative side of the 22uf cap to the dpdt was making the exact same noise when it wasn't seated properly in the breadboard. But when I put it in well it fixed the problem.

I then attached the pcb back to the circuit, trying to make sure that wire was connected properly but it still made the noise again. So would this mean that the dpdt is faulty or that my wires are not connecting well? When I use a continuity test on my multimeter it says they're all connected.

 

[Big Monk]

Does manipulating wires when all hooked up in the enclosure mitigate the noise?

 

[Cybercow]

How actually old are those NOS eCaps? Have you measured/tested their actual values?
All electrolytic capacitors tend to dry out over time and drift from their original intended values.
Might be worth a look.