Fuzz Face almost works when hitting the strings hard

[billkahler]

Built a positive ground Fuzz Face from tonepad, using their board and Small Bear GTs, subbing Steve's resistor selection for R2,3,4,5. Checked all resistors, caps, solder joints - even took the footswitch out of the circuit and wired the jacks straight through. Can't get it to work correctly but I can almost get a signal through, (that is it resembles fuzz but crackles and quickly craps out), when I really lay into the guitar. Could it be I need to use a lower value at R1? Also, I've socketed the trannies but have not yet clipped the leads. I did jam them into the sockets pretty good though.

If anybody has an idea what to look for or do, I would greatly appreciate it.

Thanks,
Bill

[R.G.]

Every defect which presents as "no sound until I hit the strings hard" is a biasing problem. There is not enough bias being presented somewhere to turn a device slightly on, into the linear amplification region.

Which device? What bias?

There is no way to tell without measuring. Go read "Debugging: What to do when it doesn't work" and provide that info. It's most likely that we'll be able to tell in a few minutes.

[Fuzzbumper]

Bill,

I had the same problem with my "Jumbo Tonebender" 3 knob Fuzz.  After hours of circuit debug
turned out I installed the MPSA18 transistors backwards, due to misunderstanding the location of
Emitter, Base & Collector. Hope this helps.
                                                                                                    Fuzzbumper... 

[billkahler]

Thanks for the help guys. I'll keep plugging away at it.