OpAmp Big Muff - bypass fine but high pitch whine engaged

[MonkeyKing]

Hi all, I used to make loads of effects and even my own tube amp years ago but I've recently got back into it with an IC big muff and straight away got problems!

Bypasses fine and clean, but when engaged it's only a high pitch whine or squeal without any signal coming through - each of the knobs affects the whine too.

I've checked the wiring (please dont attack for using the same colour, I know my sin!) And checked for bridges and knifed between traces- I've tried different opamps too with nothing changing.

I can't remember what to do next other than plea for help! I couldn't find any similar issues through search or even some readings to compare (like I can remember how to take them)

Any input is greatly appreciated!

[antonis]

HI & Welcome..

Almost all board tracks look suspect for shorts..
(have you checked them with a DMM..??)

[MonkeyKing]

Yeah I miss my old trusty iron and decent solder, supplies here are abundant but trash  I also miss etching boards instead of slicing through vero!

After making cuts I checked with dmm, and again after populating.. might get them all flowing again to tidy it up and try again, just hoping I made an obvious mistake for a quick fix 

[MonkeyKing]

Just an update - reflowed everything and checked between tracks again, the guitar signal comes through now but with the high pitch oscillation(?) too
So something is shorting somewhere right?

[toneman]

get a good magnifying lens to CloselY inspect between the copper traces.

Use back of xacto blade to scrape between the traces.

U should see NO solder Between the copper lines, unless that was intended.

15W iron in more than enough.

[MonkeyKing]

Ok well I cleaned and checked both with dmm and visually with a magnifying glass and nothing, so I built a second one and it's exactly the same issue... has anybody else built this layout?!
This second build is cleaner and I've already double checked with a meter after every single connection and it's exactly the same issue 

[antonis]

Does it oscillate even with Sustain pot all the way down..??

[MonkeyKing]

Sorry for the late reply - yes even down its oscillating, all the pots effect it like they should

I changed the small tants for box caps and that didn't change anything.

I always had the volume pot pretty low because of the horrible noise, but I've just realised this oscillation is audible through the bypassed clean signal too?

While poking inside I happened to have my thumb pressed over the bottom right corner bunch of traces (where sus 1 and 2 board connections are) and my other hand on the grounded enclosure and the noise disappeared briefly, which happened a couple times of trying afterwards but I cant isolate exactly what's happening..

Is there something there that should be grounded but isn't? Is the switch/wiring or something causing bleed through?
Again I've more than triple checked for bridges on both builds now, I'm stumped 

[TeleHB]

Greetings,

After reading this thread I decided to try the build, and encountered the problem described. I found that lowering the 560K feedback resistor to 510K sorted things out. I hope this is helpful.

[iainpunk]

welcome to the forum!

its uncommon for a first time poster to contribute help instead of needing help, very nice!
i think a 470k is more common in most peoples resistor stashes 

cheers

[MonkeyKing]

Beat me to it! I saw somebody else online had did this - I can confirm it's the solution.
First I tried 510k but that didn't help, 470k did the trick though
I can finally rest knowing it wasn't just my poor craftsmanship  thanks everyone!