ampeg scrambler high pitched whine

[kodiakklub]

just built one up based on the tonepad version. I found some actual BC169B's on ebay that came from the UK to make it "dead stock". it sounds amazing except there is a high pitched whine in the 6k-8k range perhaps. even with the volume knob all the way down, you can still here it a bit. the attack knob has no bearing on the whine. i havent  yet experienced a "noisy" transistor, could it be that? could I meter it while its in the circuit? what values am i looking for? thanks all......

[PRR]

High-pitch whine is usually layout: output too close to input.

[kodiakklub]

cant be that unfortunately, they are on opposite sides of the board. its tonepads layout, but i etched the board. so i can rule out it being one of the trannys?

[kodiakklub]

crazy idea i just had on the subway on the way to work: I reuse my 3pdt footswitches on occasion (this being one of them). could i have nuked the contacts enough internally from reuse that there is a very small potential between the in and the out within the switch? anyone every have this happen to them?

[reverberation66]

I don't think the switch is the problem

[kodiakklub]

could this be an oscillation occurring so fast that it causes a squeal/whine? and what would typically cause an oscillation?

[kodiakklub]

Finally got back to the studio today to debug. Im getting about 215 ohms through the main 100uf filter cap to ground. Anybody think that would do it? I sadly have no cap to replace it at the moment.

[kodiakklub]

SOLVED!!!::it was indeed the 100uf filter cap. i had one in a muff project i could steal. sounds killer now!!