Help with a Two Comparator that I might have fried 😬

underscores
1

Hey all,
Recently built a Two Comp circuit that I wanted to semi-eurorack. I was trying to figure out how to wire the power without a barrel plug (just wire directly to the contacts), and I think I might have poofed something. I tried a few different combos of +5v and ground on the contacts and never got any life out of it. I know this isn’t the proper way to do this, I admittedly trying to do it quick and dirty, so if I fried something thats on me. Any help would be appreciated.
Thanks!

1 Like
2

ahh sounds like you were mainly on the right track to get it mounted in a case!

it could be made clearer which is +5v and which is GND on the pcb tbf… all of these circuits use ground planes → so u should be able to tell which is GND because the tracks open up to plane…

heres the view from the kicad pcb editor:

image
image1404×744 58.5 KB

it is unlikely that the whole board is damaged, even if you did wire it up in reverse.

first i would double check that it is not working when powered correctly:

  • had you seen the circuit working at all yet ? ie could it be possible the problem is somewhere else on the board and not the power supply?
  • do you see the signal being passed through when switching bypass the toggle ?
  • then what happens when you switch it to the effect ? (and wiggle the knobs?)
  • if you have a oscilloscope i can help you debug where the problem is by checking a few points…
  • if something is fried it is likely to be only the comparator ic - did you use a ic socket ? could be as easy as popping this out and trying another one ?
3

Thanks for answering back so quick!
I’ll try wiring up properly when I get home from work today.

  • In one position it seemed like the TV I had it plugged into saw video signal, but it was still a black screen. I didn’t hold it for very long for fear of hurting something if it was wrong, so I powered it off as soon as I didn’t see actual signal.
  • I did see signal when using the bypass switch.
  • I don’t have an oscilloscope sadly.
  • I did socket the IC. Definitely have learned to do that the hard way XD.

I’ll let post again once I have it wired up and do some more tests.
Thanks!

4

OK, Finally properly wired this up, and still not getting any video signal. Let me know if I need to poke around, or just replace the IC XD.
Thanks!

5

i would try replacing the ic.

can you post a picture of the front and back of the circuit ?