ADA flanger not working. Seeking wizardly advice

Started by Herman, February 16, 2017, 06:45:52 PM

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I am working on an ADA flanger, I believe it is a reissue from the 90's. I have read many helpful posts on this forum and I hope you all can help me solve this puzzling pedal.

It came to me not working, only passing clean signal. I inspected all the caps, chips, pots switches etc... and found no clear faults, so after some reading I decided to replace the cheap and readily available i.cs. And wham, she came to life and I was happy.

What a radical pedal! Then, after about two months it failed again. Would work intermittently, suspected capacitor failure. Replaced all electrolytic caps, and Q1. No dice. I could driver her into self oscillation with the trim pots, but only seemed to be producing half the sweep. kinda sounds like a bubble pooping then whooooooossssssshhhhhhhhhh blip....then silence. And that time could be effected with the speed control, but only in self oscillation. Input signal could be traced through to the input of the mn3010 ic but the output was a mess. So I bit the bullet and ordered an mn3010 and waited a month and a half for the slow boat from china. Annnnnnnnd, no difference. So sad.

So now, I have reviewed as much info as possible, obtained schematics and checked voltages and replaced a ton of parts. Ive scoped and probed and still cant nail it down. My main suspect is something with the power supply to mn3010. I see the DC voltage on the output pins vary with the self oscillated output, between 7 and 14 volts. A post on here said their output pins sat at about 7.5 volts. Honestly I am no wizard with the bbd. And the op amp in IC4 seems to be slamming on the rails at the same tempo. The traces on the board are all gnarled and look like old tin foil bubbled up, but continuity testing shows they're ugly but functioning.

IF any of ya have any help for this stumped chump I would be so appreciative. I'm about ready to breadboard the circuit one part at a time cause I cant keep chasing gremlins in this old machine.  Thank you.


Quote from: Herman on February 16, 2017, 06:45:52 PM
Would work intermittently
The traces on the board are all gnarled and look like old tin foil bubbled up

I don't know the circuit, but intermittent function is almost always due to a bad connection.  Could be a cracked solder joint, could be a bad connection between the lug and track of a pot, lots of possibilities.  If you can post the schematic you're using, can help everybody get on the same page, one schematic's IC4 might be the next schematic's IC2.


The schematics can be found over at moosapotamus website in the archives at the bottom of this page

Its revision 4, that's what ive been using. Its a zipped file or I would just shoot the pic over to ya all.


Check clock rates @ BBD's pins 2 and 6, they should be 17.4KHz min. and 650KHz max. or 34.8KHz min. and 1.3MHz @ 4047's pin 13.
Maybe max rate is too much high and lead to "bubble pooping".
Check bias setting. (O-scope suggested).
Follow "Calibration and Bench Test Procedure" on Charlie's web page.
"NOT FLAMMABLE" is not a challenge


Thank you. I will update when I get this dog running

Paul Marossy

I've repaired a couple of those ADA flangers. If I remember correctly, I had one that only passed a clean signal and it turned out to be a bad FET in the Threshold section.