OH SNIP -- Boss DD-2 back from the DD-dead

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filtercap
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OH SNIP -- Boss DD-2 back from the DD-dead

Post by filtercap »

So I have this DD-2 delay pedal that hasn't made so much as a blip since the early 90's when a reversed-polarity power adapter took it out. I never tossed it, just used rack-unit echoes for a while (this was the 90's after all) and eventually got a DD-5. I always assumed it had some deepfried caps-n-chips or whatever.... Until the other day when I got this brilliant idea that would have occurred to any of you ages ago: read innernets.

The pedal.
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The =main= circuit board.
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So I find out on internet that there's a "zener" diode in the DD-2 that they purposefully reverse-wire between voltage and ground. In the case of over-voltage or reversed polarity, the diode sacrifices itself for the good of the community and becomes a short to ground. To revive the pedal, all it takes is one quick snip of a diode lead (in the yellow circle below).

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Short removed, pedal works!

I replaced the zener anyway. Here's the replacement threaded through the board, before soldering & trimming.
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I AB'd the DD-2 vs. the DD-5, and I think the DD-5 has a slightly fuller sound. But the DD-2 has some interesting quirks of its own, and it's good to have it back in action after all those years on the shelf.
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Bacchus
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Post by Bacchus »

That's amazing.

I was half scared to scroll down because I imagined you doing insane stuff on a board that populated.
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Mike
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Post by Mike »

Well played! I've had to bring a few pedals back from a similar fiery death, but some op-amps were lost. :-/
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Gavin
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Post by Gavin »

Kewl. What a nice story of resurrection.
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Doog
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Post by Doog »

Hooray for reanimation!

DD-2 WANT BRAAAINS
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NickS
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Post by NickS »

Nice one!

I did a similar one last year. On the original (Mk. 1) Boss CH-1 chorus the protection diode is SMT and wasn't big enough to cope with the full current from the PSU, so burnt up causing PCB damage then went open-circuit allowing further damage -the sacrificial short became the 5v regulator for the logic, but fortunately the chorus chip itself was OK.

All they really needed to do to prevent burnt boards and more damage was to put in a pico fuse. Cheapskates.
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