I have a Boss DD-3 (square chip taiwan version) in my bench with a very weird problem. I found no similar problem online, nor a solution for it. It is driving me nuts.
It passes sound on bypass no problem but as i turn it on it has a constant a noise (that can be clearly shaped by Delay Time, Volume and Mode, but very subtle by Feedback).
- sounds ok on bypass
- noise is there even without input connected.
- all electrolitic caps were changed (!)
- all tantalum caps were checked, ok.
- most ceramics were cheked. too many to keep track.
- many resistors checked.
First i thought it would be a feedback problem (because it sounds as if it has almost infinite feedback). but even removing the feedback pot and the caps around it, the noise continues. I am afraid it is the main chip that's gone bad.
Anyone experienced something similar with this classic pedal?
(Schematic annexed)
It passes sound on bypass no problem but as i turn it on it has a constant a noise (that can be clearly shaped by Delay Time, Volume and Mode, but very subtle by Feedback).
- sounds ok on bypass
- noise is there even without input connected.
- all electrolitic caps were changed (!)
- all tantalum caps were checked, ok.
- most ceramics were cheked. too many to keep track.
- many resistors checked.
First i thought it would be a feedback problem (because it sounds as if it has almost infinite feedback). but even removing the feedback pot and the caps around it, the noise continues. I am afraid it is the main chip that's gone bad.
Anyone experienced something similar with this classic pedal?
(Schematic annexed)