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Mini Mu troubleshooting

Started by thebcrew, August 17, 2021, 01:13:07 PM

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thebcrew

I recently built two mini mu pedals for friends after seeing that the naughty fish (which I've built for myself) was discontinued, and both of them seem to be having the same problem that I cannot figure out (resulting in no sound coming through when the pedal is on, bypass works fine). I disconnected the one audio board from its switching board and can confirm that on it's own, V- and V+ are delivering roughly -8.5V/+8.5V respectively. However, once connected to the audio board V- reads 0.56V and V+ reads 4.39V. IC voltages are all out of whack when compared to the build doc, with pots and switches in the middle positions and drive switch set to Down. I've verified all component values and reflowed all solder joints but something is clearly wrong and I must have made the same mistake on both of them - hoping someone can recognize what that is.

OPA134
1    1.79
2    1.01
3    0
4    0.57
5    0.9
6    1.08
7    4.39
8    3.53

LM358
1    3.09
2    0.47
3    2.17
4    0.57
5    0.14
6    0.65
7    0.66
8    4.32

TLE2074
1    3.63
2    3.61
3    0.63
4    4.36
5    0
6    0.02
7    3.63
8    3.46
9    0.06
10   0
11   0.56
12   3.61
13   3.52
14   3.53

Many thanks in advance!
-Lars

Aentons

Looks like you have a dual opamp opa2134. You need a single opa134

thebcrew

Lol, that'll do it, I'm an idiot, thank you so much!