SOLVED Big Muff not working

[almondcity]

After 12 successful builds with no issues, the 13th has beaten me. I get bypassed sound, but no sound and no LED when activated. I used sockets for the transistors and trimmers for R7 and R12 I believe. Using the Green Russian values.

The only thing I can think to try would be removing the trimmers or maybe reflowing the DC jack connections, otherwise I have no idea why my LED is at least not working.

Can anyone spot any problems?

Thanks

 

[zgrav]

is the pot under the board insulated from touching the pcb?
have you taken any measurements with a meter to see if you are getting power at the transistors (or power at the LED, for that matter).

 

[almondcity]

Yes I have a dust cover on the back. I do not have a multimeter at the moment, though this may prompt me to finally get one

 

[zgrav]

yep. get the meter.

 

[BuddytheReow]

Can we see the other side of the board?

 

[almondcity]

If I disconnect the power jack I can get shots of the bottom. I may need to clean the bottom as I forgot to do that also

 

[almondcity]

minor update: when I engage the circuit and increase the volume pot all the way, I can hear an increase in the volume of a small background noise. I'm not sure what this means if anything

 

[BuddytheReow]

Sounds like the signal is shorting out somewhere

 

[almondcity]

I'm confused that the LED is not working, my understanding was that it's a separate circuit? Unless the two circuits have the same trouble spot somehow

 

[Chuck D. Bones]

Are the trimpots the only thing you did that is not in accordance with the Build Docs?

Just to be 100% clear, you used the Build Docs for the Muffin Fuzz rev date 07.28.20.

If the LED is not turning on, then either you're not getting power or the LED is hooked up wrong. The off-board wiring looks ok. Pix are not great, but I think we can muddle thru.

You should visually inspect everything (parts, solder joints, wiring) because it's very likely you will discover the problem.

 

[almondcity]

Yes, should be just the trimpots, and for transistors I have 2N5210 socketed right now. The trimpots were a pain to get in so I might try to remove them and put in the standard R values

I can get better pics but I've looked at my joints and didn't see anything

 

[almondcity]

I'm starting to wonder if my LED is in backwards. The schematic shows a square pad on the left but the board is marked with an A there

 

[Coda]

I'm starting to wonder if my LED is in backwards. The schematic shows a square pad on the left but the board is marked with an A there

The long leg goes on the side marked “A” (anode). Even with the LED reversed, you should be getting sound.

 

[zgrav]

have you tried adjusting the trimpots while putting a signal into the pedal? do you hear any change in the sound when you adjust the trimmers?

 

[almondcity]

I tried the trimmers and hear no sound when adjusting them

 

[Chuck D. Bones]

I can get better pics but I've looked at my joints and didn't see anything

Keep looking. Check all component values and orientation. Check the power wiring.

 

[zgrav]

you need to pull the board and take a close look at the other side. and share a good pic of that side if you want others to take a look as well.

 

[almondcity]

Thanks for everyone's help so far. I plan on doing a hard inspection tonight to check that I didn't screw up anything obvious. In a few days when I get my multimeter I will try to troubleshoot with that. If still not solved I will disconnect the board and get nice shots of the bottom. My gut says that the trimmers are no good so maybe I pull them and put in sockets

 

[almondcity]

Also just thinking, isn't it possible I got a bad DC jack or fried it? That could explain why no power to either circuit

 

[Chuck D. Bones]

If you review the troubleshooting forum, you'll find that the #1 cause of a pedal malfunction is a problem with workmanship. Swapping out parts randomly will probably not uncover the root cause, but does run the risk of collateral damage. If you can't find the problem by inspecting the top of the board, then you 'll need to remove the board and inspect the bottom for shorts and bad solder joints.