I am trying to repair this early DD-3. There is a very faint delay sound even with the level all the way up. Also the direct guitar sound only appears on the Direct out jack and not the mono out jack.
I have read the thread Tony started on his faulty DD-2 which had similar problems and so I have some ideas from there to try, but I noticed that my Q9 looks fine and not broken like on Tony's.
On initial inspection it looks like someone has tried to repair it before but used some dodgy solder, because on some parts of the pcb it looks like it has oxidized? (Look to the right of the NE570 and around D6). I have tried desoldering it to repair it but my 18watt iron struggles to melt this solder. I also noticed that the ground track around the NE570 looks burnt near the two capacitors C21 and C22.
It also looks like the protection diode has been replaced so maybe the pedal has had a reverse voltage applied to it.
Does anyone have any tips on how to proceed.
Solder Side of PCB near NE570 Q9 Transistor Protection Diode D6 Solder side of PCB near D6
I can help you with this... tied up until the weekend though.
What's the part number of D6?
The symnptoms indicate maybe something around IC1a. This opamp mixes the delay and dry signals. The "direct" signal does not go through it. So it's a likely suspect.
Faulty Boss DD-3 long chip version
Posted - 09/10/2009 : 23:59:51
