lofomofo debug - kinda embarassing

[bryantabuteau]

Hi, I just finished a BMP and an 808 clone with a clean blend circuit, and both worked perfectly first time, so I thought I'd try the little lofomofo circuit, since I'd just got some 2n2222 trannies.

http://www.geocities.com/tpe123/folkurban/fuzz/lofomofo.gif

tiny little thing, should be easy I thought.

wired up according to dragonflys vero layout.

plugged it in, no go.  swapped trannies, nothing.

all components as specced, no substitutions.

checked with an audio probe, no signal past the first cap .  removed cap and measured it, all sweet. 
jumpered the cap, now i get a faint signal that when hit hard distorts slightly.

now, i realise the first cap will take out most of the bass, but the tranny should boost the signal a decent bit I would have thought.  here are my voltages :

Q1 - 2n2222
C : 1.2
B : 0.75
E : 0

Schottky - 1n5817
A : 0
K : 0.58

anybody know where to start debugging this one?
any thoughts would be appreciated...

[bryantabuteau]

bump....

[petemoore]

  Not absolutely certain but the transistor looks like the collector bias is low, not sure because this circuit gets wierdness from the transistor bias/misbias I bellieve....
  Here's what I do with little buggars, DMM them...continuity mode and resistances...check all connecitons are made by counting them at each node and verifying that they're actually made with the DMM, test resistances of resistors, but bear in mind there may be an alternate path for current so these readings must be thrown out, 'mathed out'...or at least analyzed if they're 'lower than what's 'seen' at first glance. Detaching one end of a resistor from the circuit of course gives you an accurate reading of that resistors value on the DMM. I've had very few bad resistors, caps more, transistors most, haven't had many blown parts, but it's also a small possibility.
  Just counting the connections at a node on the schematic then on the circuit board may be an approach that identifies the problem, then on to the next...
  Transistor pinout hookups can be deceptive...double check that a few times again...

[tatems]

I have the same problem 
Could the problem be that i'm using a 2N2222A?

Cheers
Tatems

[bryantabuteau]

Thanks for your help Pete.  At this stage, its probably quicker for me to just go and make another circuit on my breadboard and start testing everything there,  oh, and I am using the 2n2222a transistor, i thought that was what was specified.  Maybe I'm wrong.  In any case, people have had good luck with many different transistors, they just have to be noisy and low hfe apparently.  Strangely enough, i don't notice any difference in sound with the transistor reversed, so its gotta be biased wrongly somehow.

[bryantabuteau]

well, all sorted.  The 2n2222a works fine.  My breadboard build works perfectly.  I guess I'll go perf or vero it.  Still unsure about what is broken in my vero build, but at least I know all my component choices are sweet.