Here is a picture of the damage to the PCB itself. The diode on the other side seems to test good. We think there is short or broken trace or traces somewhere inside the mess pictured. This is the only MK2 we have to look at, so it's hard to compare. The only trace that is visibly damaged is the AC sense line, but that only affects which mode the player operates in not whether it functions or not. The copper plane in the scorched area measures about 60 ohms relative to ground. Any ideas?

Stu

Ugh! What a sad photo...

My wife's motherboard blew 3 weeks ago. I opened it, and lo, failed capacitor.

Isn't that PCB multilayered? There could be damage to the layers beneath the scorch if there are any traces under there. Perhaps PCA could help you out with a schematic so you can bridge that whole area?

This doesn't help the problem (since empegs are no longer made), but screws coming loose and falling out inside an electonic component is not something I would ever expect to hear be a problem. I don't recall ever seeing it happen. Maybe I was lucky..

Anyway it is a shame and ironic that perhaps the most common defect in such a complex machine is in one of the oldest and simplest gizmos on the planet..

Holy crap!!

Every unit I've seen in this state (maybe 5 units) have been fixable. You need to do this:

- Remove the short, however you can. In the past I've removed the 4-pin molex and drilled out the offending hole. Careful though, as this is a multilayer board. Really, the power/ground planes should have been pulled back from the input area, but you live and learn

- Rewire power so that the power and ground paths are again correct.

The problem is cause either by a fallen screw or by someone managing to short car 12v against the grounded case, meaning there's a huge amount of current flowing between the (unfused) empeg ground wire/ground connection and the case/mounting holes.

Hugo

Oh, it happens often enough, in all sorts of different equipment. I've seen something similar happen a couple of times in VCRs, but in that case there is normally a horrible grinding noise as the mechanism becomes irretrievably wedged solid. I recently stripped down a ford DOHC engine sourced from a running vehicle, only to find a fairly large screw jammed solidly in the timing chain, which would explain the noise Screws unscrewing themselves is always a possiblilty wherever you have vibration, and it's almost impossible to eliminate completely. At least without a welder, which makes maintainance difficult...

pca

uge amount of current flowing between the (unfused) empeg ground wire/ground connection

can we somehow jerry-rig a fuse into the wire for some preventive measures? (along with tightening screws every now and then, of course).

can we somehow jerry-rig a fuse into the wire for some preventive measures? (along with tightening screws every now and then, of course).

Sure. Which wires are which are obvious. Both inside and outside the player. Go for it.

what rating should i fit it with? 15A fuses or higher? Not really sure how much power the empeg generates when there's a short.

What you're really interested in is how much current it uses when there's *not* a short.

There is a 60 ohm short between ground and an unknown internal layer. We've removed the 4-pin molex connector, but still can't tell what the source of the short is.

Stu

Unknown internal layer? The only ones in that area are the power layers. It'll either be ground, 3.3v or 5v. Which one is it?

Hugo

I just wanted to jump in and say a quick "thank you" for everyone's help. I want my baby back...

Yeah, it's the 3.3 volt supply. We should have caught that when we were probing, but it was late and I guess we missed it. Now how doe s one safely remove a short that can't be seen?

Stu

Very carefully?

I've done it with a small drill bit before, drilling the hole out ever so slightly then trying to clean up the hole, then re-checking for the short.

Hugo