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whostheboss
Copper Member
USA
2 Posts |
 Posted - 01/06/2009 : 23:01:17
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Hello guys, first post here. I've been lurking around here for awhile and you guys have helped me out a lot without even knowing it, so thanks! Anyway, I just purchased a broken long chip DD-3. The pedal had the same symptoms that Tony had in the "new dd-2 day" thread:
"In modes short,med and long there is no power to the effect at all (dry signal still bypasses). In hold mode, the pedal powers up switched on and stays on. In all instances, the footswitch (which tests fine) has no effect - it doesn't turn the s,m,l modes on and it doesn't turn the hold mode off." -Tony.
Except mine had a faint oscillating sound and responded to the feedback knob by changing its pitch. It passed a clean, unaffected signal through the wet and direct outputs. Once I changed the D6 out for a new one, the LED reacts like it should but now the oscillation has gone away. The signal still passes through both outputs as before. I have a multimeter but I don't know where to begin testing. Can anybody point me in the right direction? I know you guys are probably sick of DD-2/3 problems by now  |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 01/06/2009 : 23:20:30
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Hi whostheboss
Welcome officially to the forum from Australia.
Do you have the DD-2/DD-3 long chip schematic?
Look in the schematic links thread, try the free-info link,
and search for the DD-2, it's the same, for the long chip.
It sounds like the 78L05 5V IC voltage regulator took a beating as well.
It's circuit designation is IC10.
These can be damaged very easily, & luckily, tend to go open circuit.
It looks like a standard little black transistor, but it's actually a 3 pin 5V 100mA regulator.
It regulates all the 5V rail for the Digital part of the circuit, & it sounds like that's the part that isn't working.
Also check C51 100uf 16V. for any signs of damage, it's on the DC input side, & in parallel with D6, the protection zener.
What did you replace the protection zener with?
Upload some pics if your not sure,
& look in the pedal internals pictures thread as well.
Regards Dr. Bob 
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DeFrag
Moderator
USA
3409 Posts |
Posted - 01/06/2009 : 23:21:21
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Welcome to Bossarea whostheboss!  |
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whostheboss
Copper Member
USA
2 Posts |
Posted - 01/07/2009 : 15:54:03
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| Thanks for the warm welcome guys, and thank you very much for the help Dr. Bob. I replaced D6 with a 11v 1w zener diode. IC10 appears to be the culprit. Which means I have to wait for parts to see results. I don't have a camera but it be interesting to see since the guy before me burnt off 3 separate solder pads, so I had to run thin copper wire everywhere. I checked the connections and everything seems fine for now. I'll return with the results as soon as the parts come. Thank you again Dr. Bob! |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 01/07/2009 : 16:06:31
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Hi whostheboss
You're welcome.
It would be interesting to see some pics, of the other guys shoddy work, & the effort you had to go to to repair the damaged pads & tracks.
It's great experience for the guys/girls who are less technically inclined & are trying to learn more the mystical electronics Voodoo...
Lets us know how you get on, when you get the LM78L05
You know at a pinch, when I have run out of the L series T092 regulators.
I have carefully trimmed off, & filed the metal tab, on a standard T0220 LM7805, to make it smaller, & I have fitted that in its place.
My first Justina Tuner was repaired that way, & is still going strong today.
Good luck.
Regards Dr. Bob |
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Yet another DD-3 problem
