Fuzz War / OCD Combo Pedal High Pitched Squealing Issue

[duck_arse]

on the ocd, you can add the series resistor between D1 and C4. C10, even though not marked with value, will be suitable. same, between R25 and C14 on the other, so it looks like you've saved yourself 2 electros.

your circuit will only draw as much current as it needs (unless you have a fault, which usually comes with its own smoke). a supply with a greater capacity is not a problem, less current capacity is.

[Hexjibber]

on the ocd, you can add the series resistor between D1 and C4. C10, even though not marked with value, will be suitable. same, between R25 and C14 on the other, so it looks like you've saved yourself 2 electros.

Ok cool, thanks for that! So if I understand correctly then I just need to solder the resistor to the pads of D1 and C4 that go to ground? Apologies, I'm still at the learning point of interpreting schems into what that means in terms of holes on the board! :S

[duck_arse]

not so easy. you need to put the resistor in series with the 9V. I don't know the board layout, so it might be easiest if you put the resistor between the 9V supply and the board itself, as a quick test anyway. if it works, you will probly need to cut a track or 2 on your board.

[Hexjibber]

not so easy. you need to put the resistor in series with the 9V. I don't know the board layout, so it might be easiest if you put the resistor between the 9V supply and the board itself, as a quick test anyway. if it works, you will probly need to cut a track or 2 on your board.

Oo-er! Not had to do anything like that before, I use pre-fabbed double sided boards from a kit, will try the resistors between the board and 9V as suggested and see what happens, what would be the downside of just leaving them like that if it does work?

[duck_arse]

two more points each board where a wire could break. if they don't work, easy to remove. and the cuts won't be to hard, if they needed ......

[Hexjibber]

Hi guys,

Update on this as I still haven't managed to eliminate the oscillation.

Tried the resistors as suggested above but alas, no change.

Tried various way of wiring the two circuits up, specifically the OCD which is causing the problem, input grounded on bypass, output grounded on bypass, neither grounded on bypass, none of which worked.

My last thing I can try is shielded wire, the input and output wires to the OCD pcb change the sound of the oscillation when prodded so they seem to be related to the problem but I'm not sure why, should I try shielded wire on both of these or just either one?

Totally at a loss with this one, both circuits work fine when wired independently, the oscillation only occurs when both are wired on to the selector 3PDT and the Fuzz War is selected, hence the oscillation seems to be coming from the OCD. I even pulled out the IC of the OCD to kill the circuit and hey presto, no oscillation! Just don't know why it's happening and is very frustrating!

I'm presuming it's related to the two circuits sharing ground or something but at this point I'm just grasping at straws!

If anyone has any ideas I'd be glad and very greatful to hear them!

Cheers,
Graham

[induction]

In your picture, the output jack signal wire runs parallel and very close to the output wire of the fuzz war, the input and output wires of the OCD, and a few others. Have you tried moving them apart and/or shielding that output jack wire? Even if there is oscillation in the OCD during bypass, the sound shouldn't reach the output jack unless there is either a) capacitative coupling to the output jack signal wire, b) a faulty B switch, or noise in the ground wire. Separating or shielding those wires will eliminate a. If that doesn't work, you can try replacing switch B.

I also notice that many of your soldered wire connections on both switches and input/output jacks need to be trimmed. Something could be shorting.