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tony
Bronze Member
United Kingdom
142 Posts |
 Posted - 10/01/2008 : 19:44:56
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THE DD 2 IS FIXED!!!!!!
I'm in a dream like state over this. Can't believe a mere delay pedal can induce such feelings of euphoria - it sounds pretty nice too.
The culprit?
Q9, in a word. It doesn't make totally straighforward sense as it comes before the feedback loop, but friends, let me tell you, the problem has been remedied.
But whatever could have made Tony suspect Q9? I hear you ask, chorally. People who own DD2s often complain of difficulty in closing the pedal. The reason (and I'll be updating this thread tomorrow with pictures to demonstrate) is that Q9 is a large 2SC732 transistor perched right on the edge of the board, and, if your pedal is constructed like mine, is bent over to fit in. This leaves it's top flush with the outside edge of the board. The problem is that with the pedal assembled, it's right over the jack socket and in BOSS pedals the metal thickens up right where the jacks are. When you push the PCB down you are pressing the top of the 2SC732(as it lays flat) right up against this inner lip inside the case. So, it was mechanically damaged. When I removed it, the centre lead was disconnected. Impossible to see because of how it was fitted, impossible to diagnose using my rudimentary equipment and the schematic.
Why did replacing Q7 improve the sound so? Search me. Maybe just a higher spec part compensating in some way. When installing the new 2SC732, I positioned it upright with a smaller C35 (Which was a green film cap). The pedal closes up great now.
I'll say it once more....
THE DD 2 IS FIXED!!!!!! |
Edited by - tony on 10/01/2008 19:47:42 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/01/2008 : 20:17:40
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CONGRATULATIONS!!!!
It just HAD to be something goofy like that... The signal we were seeing on pins 14 and 15 must have been bleeding through... probably through C35. You remember one of the first points we tested was the output of Q9...
Ah well it ends well! Congratulations!!! 11-out-of-10 for perseverance!
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tony
Bronze Member
United Kingdom
142 Posts |
Posted - 10/01/2008 : 22:32:02
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Also want to thank you and Dr. Bob for your help. If you hadn't given me a point of entry, so to speak, not to mention helped me to probe safely, remove the obvious-lies via a process of elimination and not be scared of the circuit diagram I'd still be staring at the schematic and waiting for the solution to materialise in front of me. Like one of those hallucination inducing chaos pictures from the 90's.
Cheers!! |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 10/02/2008 : 08:58:28
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Hi tony
Party Time!    
Congratulations, you are now be part of the official "Tech Support team.
We will ship all our DD-2 questions directly to your home address..
Just kidding. 
On behalf of Laurie, myself & all those that pitched in;
And thanks for your kind words.
May your DD-2 live long & sing many tunes. (live long & prosper)
Take your partner out to dinner, & buy yourself a nice or a Red.
Regards Dr. Bob 
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Edited by - Dr. Bob on 10/02/2008 09:35:53 |
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starr36
Platinum Member
Canada
1172 Posts |
Posted - 10/03/2008 : 02:18:35
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a broken leg on a component because it was jammed in the case. unbelievable!
part'T'T' ... T ... t ... t TIME! LOL! |
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THE DD 2 IS FIXED!!!!!!!!!!!!!!!!
