I have an original Doctor Q. Bought new at Haight Ashbury Music in the mid 80’s. 2nd pedal I ever owned (first was a Ross distortion).
It’s been sounding faint lately so I opened it up to check it out.
Spied two 30+ year old electrolytics so those are getting replaced.
Luckily I have a lot of 10uF caps on hand.
Before re-assembly I connected it up to tweak the trimpot.
At the (presumably) stock setting the sweep is not very audible.
If I rotate it counterclockwise the sweep is more evident, but a fizzy almost mechanical sound starts creeping in.
Not the swooshy sound that changes with frequency, but a steady tone. Somewhere between fizzy and buzzy. Almost like a metal speaker grille rattle.
It comes up the harder you place, so it’s certainly amplitude related. But it doesn’t change spectral content at all.
I finally found a place on the trim where I was getting a good swoosh with little or no fizz or buzz.
But it was kind of compromised from where the sweep sounded better, but that damn fizzy buzz was audible.
I used this for a solid decade with my old band. So I’m very familiar with the sound how it was.
Curious if anyone else had this with an old Doctor Q, and found a way to eliminate the noise so that more sweepy sounds could be dialed in.
I’d rather not go in to replace the opamp or transistor, as those are obsolete parts now (along with everything else it seems!).

• This topic was modified 3 years, 4 months ago by Calaverasgrande. Reason: add'l info