Dead DD3

[Witek]

So I bought a dead boss dd3 for $5 in hopes of fixing it up, if I can't fix it, it's to the scraps with the parts and the housing to build other toys with.

This is the Version 1 board I am talking about, the one that's identical to the DD2 board.
I swapped the diode in it that protects the pedal from the wrong type of adapter. But it still does nothing.

The pedal does power up, the light stays on the whole time, but dims when you depress the pedal, and there is a faint self-oscillation happening in the pedal (so the chip isn't fried) that you can adjust the pitch of by the delay time knob. But other than that it's pretty useless.

Anyone have any ideas of what to do or check on it?

[Sock Puppet]

http://music-electronics-forum.com/s...ead.php?t=1406

Good luck.

S.

[Witek]

Ok, so I did manage to get a bit of it working properly. It now lights up like it should and bypasses. But there is no effect still. I'm thinking there's something wrong on the signal path leading up to the repeat chip.

I did however manage to get something on it working aswell, kinda. When you plug a patch into the direct out jack and just listen to the signal coming out of the wet output it does delay the signal once properly, so I can assume there's a problem with the looping part of the signal aswell. Maybe a pot problem?

[cjlectronics]

I have repaired many DD-3s and never have I seen similar fixes from one to the other. I've replaced signal diodes, transistors, resistors, and electrolytic capacitors to name a few. The good news is most of the problems are not the main CPU chip. The last DD-3 I fixed all of the mini 10uf/16vdc electrolytics were leaking. You can check for this by using your soldering iron to heat the leads of the suspect electrolytic while using your nose to smell for rotten fish. Sort of like low tide at a house of ill repute, if you get my drift.

Good luck

[Witek]

Cool
I'll give that a try, would it have anything to do with putting the signal tone very very low? I found that the pedal works but at very very low volumes, so it could be that there isn't much power being supplied to the board?

[cjlectronics]

In that case, make sure you have +5v from the 78L05 and that your 1/2Vcc is there as well.

[Witek]

In that case, make sure you have +5v from the 78L05 and that your 1/2Vcc is there as well.

Where would I check for the 1/2V CC? The +5V across the 78L05 I can do no problem though.

[Witek]

Between the ground and the +5v I'm getting 10.2V?
And the ground and +9V I'm getting 15V.

Or is the Ground -5V? so I'm just getting the potential difference?

[cjlectronics]

10 volts is not correct. +5V is supposed to have +5V only. Do you have the big chip version DD3 or the square CPU mounted on the back of the pc board version?