Broken Ibanez DML20 - easy fix?

[DWBH]

There's this €25 deal for a Ibanez DML20 that doesn't work.
Apparently these are rare and sought after pedals, so the 25 euros sound good to me.
However, I still don't know what's wrong with the pedal (the owner still hasn't answered back).
Has anyone repaired one of these? What may be wrong with it?
Is it an extremely difficult pedal to fix?

[tommy.genes]

I did exactly that - bought a broken DML20 fairly cheap on eBay and fixed it. I figured out it was simply a bad protection diode on the power supply input. If I recall correctly, the seller had stated in their post that they plugged in an incorrect power supply and killed the unit, so I had some advance idea of what the problem might be.

If you do buy the DML20, send me a PM. I bought a service manual for the original DML (not the DML20) that I can share. It is not exactly the same, obviously, but it was close enough for me to troubleshoot mine.

Also check out THIS THREAD for a mod to switch the LFO on and off that I was toying with (with help from R.G.).

-- T. G. --

[DWBH]

Thank you!
The seller hasn't answered yet, hope he will tonight.

[DWBH]

Apparently, he didn't use the pedal for a long time, because the switch didn't work. He tried to substitute it: he took it out and tried to get another one - he didn't find one, though.
Later, he got another Ibanez pedal, took the switch out, and put it in the DML. He said that now it powers on, but it doesn't work. It only produces noise.

[tommy.genes]

Check your email/PM...

It sounds as if your problem could be a bit more tricky than mine was, but hopefully the service manual will help.

Let us know if it works out.

-- T. G. --

[DWBH]

Crud, I have a short somewhere.
Using my DMM I know that my +9v and ground potentials have continuity.
Most electro caps I've measure also have continuity. Maybe one of these is in bad conditions and, thus, is creating the short?
There are three filtering caps for the 9v rail, and they all have continuity. Should I replace these first?
I've searched for cracks and solder bridges in the pcb, but I haven't seen any. It's difficult, though, as it is a double sided pcb.
Any hints or tricks in how to find a short?

I'm a bit afraid to take measurements and voltages, because when I plug my ac adaptor then RAM chip (IC11) starts to get hot as hell.

[anchovie]

If the RAM chip is getting hot then I'd guess that all the juice the PSU can give is being pulled straight through it. Your short may well be within that chip.

[DWBH]

And that means a new chip, which probably isn't made anymore.

[anchovie]

Probably not available to buy new, but do some Googling of the part number for a datasheet and other info. Remember that old RAM chips were used a heck of a lot in old computers...

[DWBH]

Does anyone have a clue in how to find shorts? I'm looking for someone simpler than substituting ic's and caps, but maybe that's just an utopian wish.

[anchovie]

I'd suggest taking out the RAM chip and seeing if the short still exists.

[DWBH]

Yes, I think that's a good idea. Last night while messing with it I noticed that the negative wire from the battery wasn't connected to ground (with no AC adaptor plugged in) - which is a bit odd. Maybe a faulty DC jack? -> rookie's mistake, nevermind.