Old MXR Micro Flanger - Regen knob not working

Forum dedicated to helping people debug and troubleshoot non-functional pedals or builds. Please use an clear and informative title, indicating circuit and basic problem. Don't forget to mark the issue as fixed if this is the case.
Post Reply
User avatar
dme0000
Information
Posts: 1
Joined: 27 Jan 2022, 17:18

Post by dme0000 »

I found an old MXR Micro Flanger that wasn’t functioning for cheap. Replaced the 4069 and it’s passing clean and affected signal now. My issue is the regen knob seems to do nothing but make a bunch of hiss when it’s turned up all the way. Inversely, it doesn’t seem to do make the flange anymore subtle when turned all the way down. My instinct is that the tl062 is bad and always letting the full regen signal through no matter the pot setting. The pot must be good if there is hiss when it’s turned up, so it’s doing something. Any guidance would be appreciated, love the sound of these pedals.

User avatar
lolbou
Old Solderhand
Information
Posts: 2617
Joined: 18 Nov 2008, 21:38
Has thanked: 308 times
Been thanked: 225 times

Post by lolbou »

Schem for reference :
Image
dme0000 wrote: 27 Jan 2022, 17:33and it’s passing clean and affected signal now.
This suggest that U1B (TL062) is mixing the dry and wet properly and that mixed signals are present after C14. Try to audioprobe/scope the signal from here to U1A (TL062 - pin2) which appear to be working too.

Maybe your effected signal is not making its way up to the input : could be C16, the pot itself (R9) and its wiring (J7 and J6) wires and the 4k7 resistor (R8?).
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

User avatar
lolbou
Old Solderhand
Information
Posts: 2617
Joined: 18 Nov 2008, 21:38
Has thanked: 308 times
Been thanked: 225 times

Post by lolbou »

reading your post again, if the Regen amount is maxxed out, then I would suspect the pot. Replace it with a 470k resistor and/or a short and see if there's any difference at all?
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

Post Reply