Author Topic: Fuzz Face Won't Bias Below ~9v on Q2 Collector  (Read 166 times)

ammalato

Fuzz Face Won't Bias Below ~9v on Q2 Collector
« on: February 25, 2021, 08:50:27 PM »
Hey Gang, hoping you can help.  I just built two Germanium Fuzz Face replicas here...I've built countless pedals like this before but these two have me perplexed with the same issue. For some reason I can't get the collector of Q2 to bias.  Instead of the stock 8.2k resistor I first had a 25k bias pot and now a 10k pot (center and outer legs running to the resistor pads on the PCB) but the Q2 collector on BOTH pedals sweeps between 9.08v - 8.81v from end to end of the bias pot sweep regardless of the pot value used it seems.  I pulled the transistors out of one and put them in another pedal I have (with transistor sockets) and they bias up fine, which obviously tells me the wiring is off somewhere since it's happening in both pedals that I wired up side by side.  The only thing different that I did this time from previous builds was omit the LED and pull down resistor on the 3PDT daughterboard.   I've confirmed that the caps and transistors are oriented correctly.  Hoping for some help before I trash the whole board and start over.  Here are my voltages on the transistors...everything looks normal EXCEPT the collector on Q2.

Q1:
C:  .706v
B:  .114v
E:  .000v

Q2:
C:  9.02v
B: .700v
E   .692v



« Last Edit: February 25, 2021, 08:53:00 PM by ammalato »

PRR

Re: Fuzz Face Won't Bias Below ~9v on Q2 Collector
« Reply #1 on: February 25, 2021, 09:12:36 PM »
2-cent bet: the 1K pot is not connected.
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ammalato

Re: Fuzz Face Won't Bias Below ~9v on Q2 Collector
« Reply #2 on: February 26, 2021, 08:36:54 AM »
2-cent bet: the 1K pot is not connected.

SOB! That's why I love this place...You're 100% Correct.  I just realized now that I flipped the Volume and Fuzz Pots...Let me swap them and see what happens.  THANK YOU!

iainpunk

Re: Fuzz Face Won't Bias Below ~9v on Q2 Collector
« Reply #3 on: February 26, 2021, 09:39:39 AM »
2-cent bet: the 1K pot is not connected.
seems like 60% of fuzz faces that come here have that problem...
makes me laugh everytime

cheers, Iain
half man - half snail - 6 feet to scale - Snail man's - not frail - He's been - to jail - snail man is fuccing real
『snailpilled』