Dead delay: overvoltage -- repair?

[devnulljp]

So, Malekko 616 echo...fed it 12V and now it's dead.
I just opened it up and I don't see anything obviously fried. I put a battery in and it heats up a lot, so I guess something's blown and it's shorted.
What's the most likely place to look when it gets an overvoltage like that? I was hoping for a zener diode or something simple, but with all the SMC I can't tell what's going on.
Unsurprisingly, I get no signal when the pedal's engaged.

Anyone familiar? Something that can be easily replaced?

Any and all advice gratefully received.

[culturejam]

I pulled mine apart for FSB photos.

I'll have to look back at the pics. But since you say the battery gets hot when you plug it in, I'd say that some kind of "safety" feature is kicking in. Like a protection diode "ate the big one" and is now just shunting all power to ground. That would make a battery heat up quickly.

I'm kinda surprised 12v borked it, though. I think the BBDs have a 5v regulator, so they should be fine.

Look for a 1n4001 type diode right near where the 9v wire meets the board. If you have a DMM, check and see if there is continuity between anode and cathode. If there is, that's your culprit.

[McSpunckle]

Send it back to Malekko and tell them it just stopped working.

[devnulljp]

I pulled mine apart for FSB photos.

I'll have to look back at the pics. But since you say the battery gets hot when you plug it in, I'd say that some kind of "safety" feature is kicking in. Like a protection diode "ate the big one" and is now just shunting all power to ground. That would make a battery heat up quickly.

I'm kinda surprised 12v borked it, though. I think the BBDs have a 5v regulator, so they should be fine.

Look for a 1n4001 type diode right near where the 9v wire meets the board. If you have a DMM, check and see if there is continuity between anode and cathode. If there is, that's your culprit.

That makes sense -- kinda what I was hoping for a blown zener diode, but I can't tell what anything is as it's all SMC.
The pads marked "D" (for diode?) are the LEDs -- and a bunch of little chip-looking things. I can't find D2, maye that's the one

[comtrails70]

i was able to fix a trem pedal once by replacing whatever smelled burnt.(also fried)
surface mount repairs seems like it might be a bitch though..

[cloudscapes]

I've had the same thing happen to me. I think it was the charge pump (max1044) that had blown. just send it back and they'll repair/reship it for free.

[devnulljp]

I've had the same thing happen to me. I think it was the charge pump (max1044) that had blown. just send it back and they'll repair/reship it for free.

I was hoping for a zener diode, but it's all SMC. Anyone know what the charge pump is?

[nbabmf]

Unless there's a diode hiding under the DC jack, I don't see one. Check the voltage on that 2SJ634 next to it.

[culturejam]

Hmmm. I had no idea there would be a charge pump in an analog delay. The BBDs want low voltage (5v), the compander can take a maximum of 18v, and the op amps can all run at 9v. I just can't see where a charge pump would come into play. Maybe for more headroom on the buffers?

I suppose it could be U5, but I can read the markings on your pics or mine. Mine are here:
http://freestompboxes.org/viewtopic.php?f=7&t=9010

I'm still thinking a protection diode got blown.

[devnulljp]

Unless there's a diode hiding under the DC jack, I don't see one. Check the voltage on that 2SJ634 next to it.

That's the one. Dead as a dodo. Any idea where to get a replacement? (And what to search for?)
Google pulled up this, which doesn't look right:


Is the "Y" in 2SJ634Y significant? SMC? I can't find anything searching for 2SJ634Y...

I'm getting .2 V across Q10 and .1 across that big cap (C46) and pretty much nothing across the rest of the circuit. I could keep the house warm this winter with the heat coming off the battery though.
Doh!

[skatefrench]

This thread is pretty old, but to anyone who stumbles upon it with the same problem, here's the solution.

I emailed Malekko. Q10 is a FDC634P.
Datasheet- http://www.fairchildsemi.com/ds/FD/FDC634P.pdf
and at mouser http://www.mouser.com/ProductDetail/Fai ... BWe5nvg%3D

I used my hot air soldering station to remove it and replace it. It costs about 34 cents from mouser.