SOLVED: Guru question request.

[Dan0h]

Last night I was testing a tube breadboard out, and instead of going direct to my amp I went through my pedal board. The bread board ended up having 200+ dc on the output pot and afterwards my sproing pedal (last in chain before amp) stopped working. It still works in bypass and the led still lights up when clicked on but zero signal will pass through it now. I am wondering if I somehow zapped it? The other 8 pedals are all functional no issues at all. Is this a coincidence or is it possible I zapped the brick? Not even sure where to start troubleshooting. Any thoughts?

The calamity of errors lately most likely means I need to take a break from building and shift into more playing for a while. But I would like to fix this sproing as it has become an always on for me.

Thanks in advance.

 

[Robert]

Start with the simple things first. Check the voltages on the opamps and the Belton brick.

I'd start looking around C1 and IC2, if it was hit with overvoltage (on the input) C1 would be the first thing to go.

 

[Dan0h]

Start with the simple things first. Check the voltages on the opamps and the Belton brick.

I'd start looking around C1 and IC2, if it was hit with overvoltage (on the input) C1 would be the first thing to go.

I got voltages everywhere there should be. Going to do an audio probe tonight. Might be placing another order soon.

 

[Robert]

You should have dry signal even if the brick is defective. If the voltages are good I'd focus on the Input / Output stages (C1, C2, and IC2)

 

[Dan0h]

You should have dry signal even if the brick is defective. If the voltages are good I'd focus on the Input / Output stages (C1, C2, and IC2)

Ic2:
1 7.75
2 7.78
3 .083
4 0
5 8.45
6 7.73
7 7.05
8 7.13

C1 measures 101nf
C2 measures all over the place. Looking like I should swap out c2?

 

[Dan0h]

Ok if I jumper from in tip to ic2 2 and 1 it works but to 3 no dice. So it’s either the first stage of the tlo72 or the 1m resistor to ground. Going to swap the chip right?

 

[Robert]

R1 could be defective but IC2 is more likely.

Nothing has really occurred that R1 can't tolerate. That TL072 on the other hand.....

 

[Dan0h]

R1 could be defective but IC2 is more likely.

Nothing has really occurred that R1 can't tolerate. That TL072 on the other hand.....

Thank you Robert. Swapped the Ic and all is back to normal.

 

[Chuck D. Bones]

It's a good thing it was only a pedal that got fried and not you. Probably a good idea to perform a DC check with a DMM before plugging a HV breadboard into anything.

 

[Dan0h]

It's a good thing it was only a pedal that got fried and not you. Probably a good idea to perform a DC check with a DMM before plugging a HV breadboard into anything.

Very true. Lesson learned and you are right.
By the way, this whole breadboarding thing is very addictive. I did a Deluxe preamp section yesterday and the schematics are really starting to come to life in my mind now as I look at them. Baby steps but it’s fun to understand this stuff better.