Troubleshooting Mudbunny, no sound.

[Bieling3]

Just like the title says, no sound. It bypasses just fine and then when you switch it on, nothing. I've had a rough couple of weeks with this thing. I built one last month and had it up and running in a couple of hours. I'm determined to make this pedal work. As per suggestion I've:

Double checked my wiring
Double checked my part values
Double checked my part orientation
Double checked my soldering job

....And given it a lot of looks with plenty of time in between to clear my head.

Socketed 2N5088 Transistors read as follows:

Q1

C 6.62
B 1.14
E 0.71

Q2

C 6.63
B 1.14
E 0.71


Q3

C 6.12v
B 1.05v
E 0.62v

Q4

C 3.89v
B 1.14v
E 0.58v

Hopefully I can get some better pics tomorrow when I go back to work at the lab... and also take a toothbrush and some isopropyl alcohol to the board to get all the flux off it...





P.S. Yes, the diodes' legs are long... once the fuzz is up and running they're coming out and a switch is going in. Same with C10.

[icecycle66]

Are the backs of your pots grounding stuff out?

Make sure they aren't in contact with your solder points.

[alanp]

+1 on the back of your pots.

Wedge some ice-cream container trimmings or something between them and the circuit board.

[Bieling3]

I'll give it a try, also just read up on creating an audio probe, going to make one of those tonight and test all the stages. So do my voltages look alright? I'm think Q4 looks a little low...

[Bieling3]

So with the audio probe I get sound up to one leg of C2 and nothing at R6. I replaced C2 with another 470p cap and no change. R6 is a verified 12k on the multimeter. No sound at C3.

This points me to Q1.

I can hear the signal at the base, but nothing from the collector or emitter. So I swap around transistors from my first Mudbunny build, known good transistors in the proper orientation and still no sound. I triple check and reflow the solder for the transistors socket, still nothing.

I am at a loss so I'm putting it up for the night. Any suggestions... something I'm missing... next steps?

[Bieling3]

Removed the socket, cleaned up and inspected the board. There doesn't appear to be any lifted traces. Soldered the transistor in Q1. Still nothing. Desoldered the transistor, put it in the socket for Q1 in my first Mudbunny build, verified it works there.

Completely lost now.

[wstimson]

Hey, just to be safe, check out this thread: http://www.madbeanpedals.com/forum/index.php?topic=9795.0

Make sure you don't have the same manufacturing error.  Probably not, but it's worth a check.

[Bieling3]

I saw that. Doesn't appear to be an issue on my board. All I can think to do is put the transistor on my breadboard and make long jumpers over to the circuit, connecting to R5, R6, C2, and C3... either the board is bad, or more likely there is some kind of bridge I'm not seeing.

[pryde]

Are you getting signal at R4?

From looking at the solder joints on your picture above, I would reflow ALL of them. It is possible you have a dry joint as there are several that are dull and balled-up. Should have a bunch of nice shiny Hershey's kisses there 

[Bieling3]

Yes, I believe I had audio signal at R4, I'll have to reverify when I get home from work tonight. I definitely had signal from the base of Q1 and the left leg of C2... it's the collecter and emitter that seem to be giving me trouble.

[Bieling3]

Attached transistor with fly leads bypassing the board altogether. Still nothing Does this mean either C3 or one of the components tied to Q1's collecter and emitter could be bad? At this point I'm ready to strip the board.

[pryde]

You wont have signal at the emitter, it is grounded.

Signal at both sides of R4?
Did you re-flow all the solder joints?
Did you swap in new transistor?

After doing the above (and it still does not help) post some EBC voltages from the transistors.

[Bieling3]

Signal on the inner side of R4, none on the side that goes to R6... so that means R6 is grounding or something?

[pryde]

Signal on the inner side of R4, none on the side that goes to R6... so that means R6 is grounding or something?

Could be but not sure. Post some voltages for Q1

[Bieling3]

Okay lifted one leg of R6 (the one that connects to R12 and a whole lot more, and I got signal from it. Something is grounding out down the line. Do I have to lift everything down stream until I get signal at R12?