PedalPCB Pro-10 build issues

[jhaneyzz]

I've got another stumper here.

Building a pretty straightforward PCB build of a Protein clone

finally got the last components and plugged it in last night and got the friendly aroma of cooking electronics.

Double checked polarity of power and current coming in. all looks good.

The only off-script items I made were two capacitors. I didn't have any 2.7nf or a 8.2nf caps so I put pairs of poly caps in parallel to get very close to the specs on the pcb.

The image here shows exactly what I did.

Any Idea why the resistor is cooking?

[idy]

Your Capacitor subs are good and are not your problem.

The 22 ohm resistor (there are two, one for each circuit) goes between the power jack and the big caps that smooth the supply out making a filter that keeps noise out. It burns up because too much current went through it, which happened because there is a short, or a near short, between the power and ground.

If you take a multimeter and (power disconnected!) and check the resistance between there end of the 22ohm R that goes to the big cap + you will read something too low, maybe 0 ohms. If you do the same measurement on the other circuit you will read something higher, some kilo-ohms. I can't see a schematic, but it's a king of tone, right? Maybe 94k...The 22 0hm is not on the KOT. But it is a good idea to put it there.

If this checks out you will have to find the short...probably a solder bridge. Oh, and the diode next to the R could be burned out also.

[jhaneyzz]

Idy.

Thanks for the reply

I'd better not start troubleshooting this tonight. You know how it ends up when you start at midnight...

Good warning on the 5817 power diode. I suspected that right off so replaced it earlier.

The Protein is a lot like a KOT. but rather than dual Blues Breakers, it is a Blues Breaker on one side and a Nobles on the other.

[antonis]

Discharge 100μF reservoir cap (the one between Schottky diode and 2N3904 BJT) before measurement or you might get faulse readings..

[ElectricDruid]

+1 agree. You're looking for a short on the board - a blobby joint that touches one next door, a bit of solder bringing two tracks, a wire offcut jammed on the board (check both sides!) - you know, the normal stuff!!