ADA Flanger

[a soBer Newt]

Hello all.  I just got a ADA Flanger from a friend of mine to repair; I was wondering if anyone had any clues why there is a lot of distortion in the output.  I opened it up, noticed that there are a few trim pots inside. My thought is that a transistor need to be re-biased or something along those lines.  Any help would be greatly appreciated.

[rustypinto]

These will produce a lot of distortion if the BBD IC is out of bias (thats what always immediately comes to mind with BBD effects and a lot of distortion). The bias trim is right by the BBD (an IC probably labeled "Reticon"). It could very well be a different issue, so make sure you make a mark with a sharpie on the body of the trim and the piece that turns in case you have to go back to where you started. If turning the trim (slowly) one way or the other while sending a signal through the unit helps with the distortion, you found the problem!

[Paul Marossy]

It could be one of many things causing that. It might possibly need to be recalibrated. You can find info on how to calibrate it here: http://www.moosapotamus.net/IDEAS/ADAflanger/ADAflanger.html

I've worked on several ADA Flangers that ranged from completely dead to malfunctioning in one way or another. Haven't run across the distortion problem yet, though.

EDIT: But first try rustypinto's suggestion. That might be all that is required.

[a soBer Newt]

Thanks for the infromation and the sugestion about marking the body of the trim with a sharpie

[StephenGiles]

First things - forgetting the distortion for a moment, is there any evidence of flanging at all? If there is, check power voltage to power pins of ICs, which should be 15v. Check voltages at the clock output pins of the 4047 they should be around 7 volts each. If that checks out it could be just the bias trim that needs adjusting.

[Paul Marossy]

First things - forgetting the distortion for a moment, is there any evidence of flanging at all? If there is, check power voltage to power pins of ICs, which should be 15v. Check voltages at the clock output pins of the 4047 they should be around 7 volts each. If that checks out it could be just the bias trim that needs adjusting.

I would think if there was no flanging going on, that would have been mentioned. 

[StephenGiles]

First things - forgetting the distortion for a moment, is there any evidence of flanging at all? If there is, check power voltage to power pins of ICs, which should be 15v. Check voltages at the clock output pins of the 4047 they should be around 7 volts each. If that checks out it could be just the bias trim that needs adjusting.

I would think if there was no flanging going on, that would have been mentioned. 

Possibly, but I never assume anything!

[Paul Marossy]

Right. The old saying about assuming, right?  Ass+u+me

[nbabmf]

Would you mind posting the voltages you get from the IC's and the JFET?

[a soBer Newt]

Hey so i have been doing some more research on this flanger. It is the 1995 Reissue. I have been looking for a schematic for it but thus far have come up empty handed.

[oldschoolanalog]

It is the 1995 Reissue.

If you need to compare V's; I have a '90s reissue in good working order.

First things - forgetting the distortion for a moment, is there any evidence of flanging at all? If there is, check power voltage to power pins of ICs, which should be 15v. Check voltages at the clock output pins of the 4047 they should be around 7 volts each. If that checks out it could be just the bias trim that needs adjusting.

Sound advice from one who knows. Do this first.

I have been looking for a schematic for it but thus far have come up empty handed.

Join the club...
Anybody?

[a soBer Newt]

So with the 95 reissue should i just the ground ground on the jacks as ground to measure the voltages, or is this not a good common ground?

[StephenGiles]

Yes, that will be fine. I was going to say use the negative battery tag but of of course I'm probably the only one who runs one on 2 PP3s!!