Noob alert! My Fuzz Face doesn't work!

Started by Qubit, November 25, 2009, 07:08:37 AM

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Qubit

Hi Guys,

My first post here :) I've been a lurker since I got interested in DIY stompboxes and now I hope your collective knowledge can help me out. I've build a fuzzface based on this layout:

http://www.aronnelson.com/gallery/main.php/v/jpm83s-Gallery/album176/Eyelet/germanium+fuzz+face+eyelet+layout.png.html?g2_imageViewsIndex=1

Now... I have sound in bypass but no sound when put into action.
I measured the Voltages across the transistors. Maybe you guys can work something out based on these figures?

Battery: 8,95V

Q1:
E 0,00V
B 0,08V
C 0,21V

Q2:
E 0,13V
B 0,21V
C 7,85V

According to the Geofex FX debugging article, the difference between base and emitter for germanium transistors should be between 0,0V and 0,3V. The difference for Q1 is 0,08V (OK) and for Q2 als 0,08V (OK). Then it says:


Quote
If the collector is not a volt or more above the emitter (...) the transistor cannot be acting as an amplifier. 


Which should mean that I have a problem with Q1, I guess?

Any of you have any suggestions as to what I should check next or any clues to where my problem is located? I got the bug and having an amazingly good time but I want to get at least some output from my effect 

Thanks! 

Finally, some pictures... Maybe you can spot a problem that way?





anchovie

Have you double-checked the pinout/orientation of Q1?
Bringing you yesterday's technology tomorrow.

Qubit

I'll check it again tonight when I get home. It is an OC75 so red dot = collector, right?

petemoore

  Have any 2n3906's or other Si PNP around ?
  Their sound won't be like the OC's but enough to tell when it's firing on all two cylinders.
  Stick the OC's in the Hfe meter of DMM if it has one, that'll tell you the pinout in the form of a gain reading that looks 'reasonable', not good for picking transistors without leakage rating and calculating, but is good for determining pinout and that there is gain available in the transistor.
Convention creates following, following creates convention.