Big muff pi black russian problem

[scaesic]

urgh, somethings come loose or broken.

checked switch and it's fine.

im getting bypass fine, led comes on when effect is on but no sound out.

Transistor legs read

sustain:
e-0.15
b-0.74
c-4.36

Clip1:
e-0.16
b-0.73
c-4.36

Clip2:
e-0.14
b-0.74
c-4.16

tone:
e-1.11
b-1.69
c-5.07

checked pots, also fine.

[scaesic]

i found the ggg voltages.

any more ideas?

must be a wire i think.

[geertjacobs]

Are you using a (fresh) battery or an adapter?
Have you checked the wires going to the input and output jacks?
If everything seems alright, make an Audio Probe and trace the audio in your pedal until the place where it stops...

[Satch12879]

Perf or PCB?

[chunks717]

I have yet to EVER get black russian values (even when parts taken out of functioning big muff!!!) to work in any other layout.
tonepad, GGG, my own, or any other. have built plenty of muffs/variants, and they work, but cannot get one to SOUND like a black russian........

[scaesic]

bah, i probed around looking for a problem for about an hour, couldnt find anything, tried it again and it was working fine again.

bah.

the black russian big muffs have totally random values for the parts, for a start the sustain and tone pots are 60k not 100. And a lot of the caps are diff values than stated on most schems.

[chunks717]

thats nuts! I have reversed the SHIT out of at least 3 of them, and never once measured the pots! the sus. pot shouldn't matter too much, but the tone could be an issue...............I'll have a look at them.........

[chunks717]

negative.......i measure 106k tone and 96k gain, seems like a cheap 100k to me.................
as for the caps, they are all labeled, and pretty well fit the schematics....same for the resistors.
the values that vary from schem, all match each other in the 3 I have torn apart.

[scaesic]

ahwell, i switched the 60k sustain pot for a 100k, although it didnt make too much diff.
most of the other values usually swing +/-20% of the schem values in mine, although some are dead on.

i added a switch to remove the first set of diodes, i can't actually detect much difference between the bmp in 2 clipper mode or 1 clipper mode.

[AL]

i added a switch to remove the first set of diodes, i can't actually detect much difference between the bmp in 2 clipper mode or 1 clipper mode

I tried removing the first set of diodes also - I couldn't hear much difference either. I had way better results by swapping transistors and caps. And while I'm here - EH (in my experience) is not known for their Quality Assurance program nor for their "high end" components. The few Big Muffs I've been in have all had different components. I always end up just changing the jacks, switch, and re-wiring a few things. Sometimes the pots and the 9V input go as well. A bit of bullet-proofing I suppose.

AL