Boss DD-3 problem

[blipler]

Was given a faulty Boss DD-3.

It has a loud crackle that repeats at the selected delay rate, independent of guitar signal, volume, etc. It's not a guitar lead related issue. Happens whether on (new) battery power or wall wart.

Doesn't affect bypassed signal.

The crackle is like a distorted blip, as soon as the pedal is turned on with the footswitch it starts the blip. Can adjust the rate of the blip with the D.Time knob, Feedback works and Level works, can hear guitar under the blip.

Any ideas what's going on?

Thanks in advance.

[cjlectronics]

Do you have the big chip version DD-3? If so, replace the 10uf caps inside the unit. Most likely you have a leaky 10uf cap.

CJ

[blipler]

Thanks for your response CJ.

It's the DD-3 ver 2b as described here. http://www.stinkfoot.se/andreas/diy/articles/DD3.htm
Taiwanese with square BOSS chip on the back of the board.

Tried replacing all of the 10uf's. As I pulled them out they didn't look to be leaking, and after they were replaced with new parts it behaves the same way as before.

Any other ideas?

[cjlectronics]

Check for +5v at IC9. Check for +4.5v at C46 or pin 3 of IC1 with a +9vdc power input. If you can scope these points check for no noise.

IC5 pin 7 is the conditioned signal into the main CPU.
IC8 pin 7 is the filtered signal out of the CPU. (delayed signal)
You can look for the blip before the CPU or after the CPU to isolate where the blip occurs.


CJ