Fuzzrite GGG debugging. Need help.

Started by Fishtone, April 21, 2023, 10:09:25 PM

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Fishtone

Hello all! My name is Mike and I used to be a member if this board roughly 10 years ago or so. I am also getting back into pedal building after just as long. Having some issue with my first ( in a while) build. It's the MRFR (mosrite fuzzrite) clone from general guitar gadgets. I followed the wiring layout and made no changes to components and what not.

Issue: there is no sound when I activate the pedal. I get clean sound with the pedal bypassed. When I switch on the pedal, I get the LED to light up but get no sound.

The transistors should read out as such

Q1
C= .77 v
B= .63 v
E= 0 v

(Q2 should read the same as Q1)

Here are the read outs on my build

Q1
C= 8.50 v
B= 5.68 v
E= 0 v

Q2
C= 7.53 v
B= 4.25 v
E= 0v

9 volt power source (battery) is reading at 9.51 volts

I will add that for now I have had to wire lug 3 of the Fuzz (500k linear) to the bottom of the board marked Fb (the wire came off the board during debugging). I also may have jumped something near the LED by accident and may have burnt out the LED. Besides that, I have followed the directions from GGG to a T. This is the 3rd or 4th pedal kit I've built from GGG but the first fuzz style pedal.

Thanks for your help!!




PRR

#1


The Bases can't possibly be more than 0.7V up from the Emitters, which are properly at zero V.

Wrong pinout? Way-wrong parts like JFET?
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Fishtone

#2
Ahhh, I just noticed that I was sent CEN2N 3906 transistors. From some very brief research, these appear to be PNP at least... and if im not mistaken they should be NPN. I think im gonna try swapping them out with 2n2222 transistors I've got handy.

Edit: yes, those other transistors worked like a charm. Thanks again for the help!

GibsonGM

When you get it working, be sure to audition a few different transistors. The gains do make a big difference in this circuit, IMHO.  If interested, later on I can measure the gains of the ones I used to get max. sustain and smoothness.
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