SOLVED Ginormous Fuzz - no sound - Trim Pot issue?

[seangarland123]

Hi all - This is my second attempt at building the Ginormous Fuzz. It's a very minimal circuit, so I can't understand why I am struggling so much (there are only so many places it could go wrong).

I have sound when bypassed, and the LED comes on when engaged, but I get no sound when engaged. I've checked my solder joints, and they seem fine to me (no worse than any other of my 15 successful builds).

The one question I have is with the 1k trim pot. On the PCB, there are 5 holes arranged like a home plate (1-2-2). The 1k trim pot (Cermet) that I am using only has three legs, which leaves the "bottom" two empty. Could this be my problem?

See PCB board diagram for reference.

 

[KR Sound]

Those are meant to be able to fit 2 different sizes of trimmers and only 3 holes are used. The 2/2 are connected if you look closely.

How about some pics of your build? It’s probably something simple and some fresh eyes will help.

 

[jwin615]

No. That just accommodates 2 separate types of trim pots. You are fine there.
Have you built an audio probe? If so, probe the in and out pads on the pcb. That eliminates the switch as an issue. Photos could help.
Also, if you socketed anything, make sure they are making good contact and oriented correctly.

 

[seangarland123]

 

[Laundryroom David]

Are you using a bc548?

could you show us the connections to the foot switch? Might be worth looking.

 

[seangarland123]

Are you using a bc548?

could you show us the connections to the foot switch? Might be worth looking.

OMG. I think you may have solved it? It looks like I put in a 2N5458 instead of a BC548.

 

[Laundryroom David]

OMG. I think you may have solved it? It looks like I put in a 2N5458 instead of a BC548.

Different critters!

If you don’t have a bc548b, you can probably get away with using a 2n3906 or other BJT with around 300-400 hfe. But the pin out on the bc548 is C-B-E (left to right when looking at the flat side of the transistor with legs pointing down). Pinout of eg 2N3906 is C-B-E so you‘d need to flip it around 180 deg on that board.

If that fixes it, mark this puppy solved! Good luck!

 

[seangarland123]

Different critters!

If you don’t have a bc548b, you can probably get away with using a 2n3906 or other BJT with around 300-400 hfe. But the pin out on the bc548 is C-B-E (left to right when looking at the flat side of the transistor with legs pointing down). Pinout of eg 2N3906 is C-B-E so you‘d need to flip it around 180 deg on that board.

If that fixes it, mark this puppy solved! Good luck!

Yeah, I’ve got a BC548 ready to go (probably even ordered specifically for this build). Got to do some family time right now, but will be swapping it out later tonight. I’ll report back! Thanks!

 

[seangarland123]

Problem solved. Lesson learned - attention to detail. Thanks @Laundryroom David for your eagle eye on catching the wrong transistor!

 

[Laundryroom David]

Problem solved. Lesson learned - attention to detail. Thanks @Laundryroom David for your eagle eye on catching the wrong transistor!

Well done!!

 

[Nic]

The one question I have is with the 1k trim pot. On the PCB, there are 5 holes arranged like a home plate (1-2-2).

Those are really puzzling people lately !