bigmuff problems SOLVED - sounds like gate + fuzz

[stvitus]

hi

i thought it would be a good idea to choose a big muff as my first project (tonepad stock big muff schematic).

well its finished but i got a problem. the whole thing only works when the sustain pot is at about 3/4. below that mark it sounds like its played threw a noise gate or something like that. at about 1/2 and below there is no sound at all. volume and tone works like a charm.
i'm debugging the whole thing since one day and i just cant find the error.
i hope someone can help me with that thing.

ah btw i wasnt able to get a 0.004µF (C10) capacitor so i had to use a 0.0047µF, maybe thats my problem? i had my last contact with that type of stuff ages ago....

btw sorry for my bad english


EDIT: thx for your help. turned the tranistors 180 degrees and it works

[aron]

Check out the sticky at the top of the forum:

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=29816

[stvitus]

oh well, here we go:
That’s the procedure.

Here is the checklist to fill out:
1.Tone and Volume works, with sustain below 1/2 it does nothing, with sustain between 1/2 and 3/4 it sounds like a fuzz + a noise gate
2.Name of the circuit = Stock Big Muff
3.Source of the circuit (URL of schematic or project) = http://www.tonepad.com/getFileInfo.asp?id=94
4.No Modifikations to the circuit.
5.I had to substitute the 0.004uF (C10) with a 0.0047uFcap
6.No Conversions
7. Steady 9,73V from the AC adaptor

Q1
C = 15,2mV
B = 574mV
E = 7,35V

Q2
C= 3,1mV
B= 514mV
E= 9,20V

Q3
C= 13,1mV
B= 560mV
E= 7,21V

Q4 (looks a little bit odd i think)
C= 463mV
B= 1,01V
E= 7,72V


D1 = D2
A  = 512mV
K  = 291mV

D3 = D4
A = 566mV
K = 228mV

[petemoore]

Q1
C = 15,2mV
B = 574mV
E = 7,35V

Q2
C= 3,1mV
B= 514mV
E= 9,20V

Q3
C= 13,1mV
B= 560mV
E= 7,21V

Q4 (looks a little bit odd i think)
C= 463mV
B= 1,01V
E= 7,72V
 I'd check transistor orientation and pinout, it looks to me like they may be turned around, the Emitters are all the highest voltage of the three pins, should be the other way around.


D1 = D2
A = 512mV
K = 291mV

D3 = D4
A = 566mV
K = 228m

[aron]

Is this a PNP version or NPN, what transistors did you use?

[stvitus]

i used: 2N5088 npn universal Transistor. Hfe 300-900

hmmm i'll check the transistors again, thx