Mach One OD: No sound, bad connection?

SeaDub71

New member
I have watched a ton of videos over the last few weeks and took the dive on my first pedal build, a Mach One OD.

I've got power and bypass works fine, but no sound when the pedal is engaged. I took my multimeter and tried to check every single connection, meticulously scoured this thing for whiskers, even cleaned up a couple solder jobs juuuuuust in case. There are two connections that are not behaving the way I think they should, granted I know one ounce more than nothing.

First, all the lugs on the volume pot (on the right in the attached view) return a value when connected to ground, even the ground leg. Shouldn't the ground to ground beep at me?

Second, the SW spot from the board (the third from left spot bottom-center on the board, red wire going to top-middle switch spot). At either end of that connection to ground, my multimeter beeps and shows 0.0 (though sometimes it briefly shows a number like 15 and then goes to zero and beeps).

Finally, maybe a clue to someone much more knowledgeable than me: When engaged and plugged in, I can run it into a tuner and see there must be some kind of signal coming out because it shows an A#.

I am very new to this and don't have any background in electronics, so I'm sure I'm not using the proper terms. I was just trying to check everything to ground and every component seems to return a value and not cause an issue, at least with the meter, with those two exceptions above. No whiskers, I wicked away as much solder as I could while leaving the wire connected. I took the board out of the case, checked both sides, I can't figure it out. Any thoughts and suggestions appreciated, thanks, and I've already learned a lot from reading these forums, even if troubleshooting is something I tend to learn a lot about by being troubled at first.
 

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If it works in bypass, but goes dead when you engage it, it’s possible your signal is getting shorted to ground somewhere.

While you’re checking continuity to ground, you could check whether the in/out wires become connected to ground when you hit the switch.

Also, looks like you used a metal LED bezel. Make sure the LED leads aren’t touching the bezel and shorting to ground there.

I just did one of these. It’s a cool pedal. Good luck getting yours going!
 
If it works in bypass, but goes dead when you engage it, it’s possible your signal is getting shorted to ground somewhere.

While you’re checking continuity to ground, you could check whether the in/out wires become connected to ground when you hit the switch.

Also, looks like you used a metal LED bezel. Make sure the LED leads aren’t touching the bezel and shorting to ground there.

I just did one of these. It’s a cool pedal. Good luck getting yours going!
I didn't even think about the metal bezel, I'll check that today. When the switch is engaged, it's connected to ground all the way through to the last ouput points on the switch and the output jack.
 
I didn't even think about the metal bezel, I'll check that today. When the switch is engaged, it's connected to ground all the way through to the last ouput points on the switch and the output jack.
If the signal path is connected to ground, I’d usually start by looking for something touching where it shouldn’t be. Solder bridges, wires touching, etc.

Like Jimi says, correct components and complete solder joints are the right place to start if you don’t see an obvious mechanical problem. A 47 ohm somewhere that should be a 470k ohm or vise versa is a pretty classic no-sound mistake.

Pulling up a color-code chart and going through each resistor is a good step.
 
If the signal path is connected to ground, I’d usually start by looking for something touching where it shouldn’t be. Solder bridges, wires touching, etc.

Like Jimi says, correct components and complete solder joints are the right place to start if you don’t see an obvious mechanical problem. A 47 ohm somewhere that should be a 470k ohm or vise versa is a pretty classic no-sound mistake.

Pulling up a color-code chart and going through each resistor is a good step.
Thanks, I'll check. This is my first pedal build and I ordered stuff just for this and double-checked all the components, so one of the few things I am reasonably sure of is that they're all the right pieces except you can see I ordered one resistor with a higher voltage rating, so it is larger. But do I understand correctly that a higher voltage rating would not hamper the signal here?
 
Thanks, I'll check. This is my first pedal build and I ordered stuff just for this and double-checked all the components, so one of the few things I am reasonably sure of is that they're all the right pieces except you can see I ordered one resistor with a higher voltage rating, so it is larger. But do I understand correctly that a higher voltage rating would not hamper the signal here?
Correct, high voltage is fine.

We’re all reasonably sure we did it right until it doesn’t work. 🤣

Best use of your time at this point is to assume nothing and re-check everything. Doesn’t take as long as you’d think.
 
Thanks for the help, everyone. I found the problem using Jimi's advice. It turned out that on the back side, two ends of a resistor had gotten bridged. Once I broke that up, the pedal worked perfectly. Thanks, I'm excited to be making my own pedals and learning about electronics. Next up I've got all the materials to start working on an opamp Big Muff clone this week and I have a 1981 kit on the way.
 
Thanks for the help, everyone. I found the problem using Jimi's advice. It turned out that on the back side, two ends of a resistor had gotten bridged. Once I broke that up, the pedal worked perfectly. Thanks, I'm excited to be making my own pedals and learning about electronics. Next up I've got all the materials to start working on an opamp Big Muff clone this week and I have a 1981 kit on the way.
Congratulations! You’re well on your way now! It’s a good feeling isn’t it?!
 
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