Older Small Stone Osc bleed through while Bypassed.

[Jamforthelamb]

Hey Everyone,
I have an older Small Stone that I recently bought off ebay (was inop). I got it up and running again, (re-flowed some solder and voila') and converted it to true bypass. My problem is just as it states in the subject line. When I have it in bypass I can hear a high pitch whine that cycles with the osc of the circuit (really noticable with the depth switch on). What's my best solution for this ? I have it wired for the standard TB with a 3pdt (might add an LED later), should I wire it so the input of the effect is grouded when bypassed ? I haven't replaced the electo's yet (no 33ufs on hand) would that help ?

Thanks,
JFTL

[R O Tiree]

Grounding the input would be my first port of call, yes.  Try initially just touching with a piece of wire from the input pad to the ground rail, before you go de-soldering your switch.  I'd have thought that the 470k pull-down resistor (shown on the Issue J schem at http://www.schematicheaven.com/effects/eh_smallstonephaser.pdf) should already do this, however.

I don't think that replacing the caps would do anything for this oscillation noise, but it's worth doing in any case in old FX.

After that, have a look at your lead dress.  Usually, this seems only to be critical with high-gain circuits, but you never know...

[SonicVI]

Mine did that as well, even after I added a DPDT switch. It only happened with the color switch in the up position. I believe I remedied it by soldering a small value cap between ground and somewhere on the PCB, the input wire joint I think.