192 pro tools interface question/problem

Dealing with a client who at the moment has managed to break his only 192 on his slow tools Highly disfunctional system. It won't power up and he tries to do so. The unit is attempting to kick over and doesn't happen. It's kind of like a car with a dead battery. I opened it up and watched the inside as we hit the power button. The fan attempts to spin but can't get enough juice and the unit makes a clicking sounds(most likely a relay which is hidden under some PCB). Me traces it to a power supply but can't find any blown caps or resisters on the main AC to DC power supply. Has anyone expierenced this and or any suggestions what else to check for.

im not sure how it is hooked up in there but see if you can disconnect the electronics from the power supply and get the supply to fire up. it is probably a switch mode supply(no big transformer and a large heat sunk transistor(s)) and that would be your prob. they require magic and fairy dust only available at the factory to operate. everything is so interrelated that i give up and replace.

Andrew, How are you?
Yes it is a switching supply with 2 lil transformers and some trassistors. I had in mind that PCB would need a replace. Was hping it wouldn';t have to though.

I have managed to get much closer to the problem.

I ran the power with no other circuits and worked fine. Started to plug in the the i/o cards and bingo. The extrra output card he has is causing the problems. If I plug in the other cards no problems. but once I connect the extra output card problems. I am thinking at this point best to just put in a new card...

Just for giggles, you may want to check for a shorted tantalum bypass cap. As tantalums fail short rather than open, this is a not uncommon cause of having your supply dragged down. I'm going to go out on a limb and guess that it's all surface mount stuff. If you have a loupe you can sometimes see a discoloration or crack on the offending part, sometimes not. If it's new enough, Digi may just warrantee replace the thing and you can just wash your hands of it.

I had a problem with a 002R... same sort of thing, where it tried to fire up, but all you got was some clicking sounds. The problem was a bad power harness... Digi had used some cheaply made harneses for a batch of 002Rs.... I called em up and got a replacement in a few days. Maybe not the same problem... but I thought I'd share.

I found the problem. :grin:
O.k. so as b4 when unplugging the last card the unit would work fine. That meaning the original analog in,analog out and digital card worked fine. The extra analog out card was causing issues. So I just go to yanking out the card. It's blown. There is a nice big burn/black spot and some blown componants. Why they esploded I am not sure. but once the card was removed all was fine. Now comes the why?