bobo68
Well-known member
Hi,
I acquired a Quadra 650 which was in very good visual condition but would not start up. I'll make the long story short: the Quadra has a blown capacitor C203 on the underside of its mainboard:
(the cap was initially "complete" but blown - one part fell of when I tried to clean the surrounding)
The "explosion" left some smoke on the housing:
Somebody put some clear tape across that part of the mainboard (obviously after the explosion):
The mainboard PRAM battery (which of course I thought was the reason for the Quadra not starting up) was probably installed the wrong way (polarity). I ripped the old one out quickly without checking but I think it was reversed. The battery is from 1997 and still has 3,6 V - another indication that it was installed wrongly because it should have been empty by now.
The PSU is working, I can start it up by shorting output pin Pin 9 (/PFW, power fail warning) and pin 10 (+5V.TRKL). It obviously cannot be started up by the Quadra.
There is a thin film of some sticky (dried up?) stuff on the underside of the mainboard. I thought that maybe somebody poured Coke etc. into the Quadra and the mainboard got a little bath but the inside of the lower housing is clean. The upper side of the mainboard is also pretty clean.
So:
I acquired a Quadra 650 which was in very good visual condition but would not start up. I'll make the long story short: the Quadra has a blown capacitor C203 on the underside of its mainboard:
(the cap was initially "complete" but blown - one part fell of when I tried to clean the surrounding)
The "explosion" left some smoke on the housing:
Somebody put some clear tape across that part of the mainboard (obviously after the explosion):
The mainboard PRAM battery (which of course I thought was the reason for the Quadra not starting up) was probably installed the wrong way (polarity). I ripped the old one out quickly without checking but I think it was reversed. The battery is from 1997 and still has 3,6 V - another indication that it was installed wrongly because it should have been empty by now.
The PSU is working, I can start it up by shorting output pin Pin 9 (/PFW, power fail warning) and pin 10 (+5V.TRKL). It obviously cannot be started up by the Quadra.
There is a thin film of some sticky (dried up?) stuff on the underside of the mainboard. I thought that maybe somebody poured Coke etc. into the Quadra and the mainboard got a little bath but the inside of the lower housing is clean. The upper side of the mainboard is also pretty clean.
So:
- Can someone make sense of this situation? What happened here? I do not think that the cap touched the lower metal housing and blew. Could the wrong polarity of the PRAM battery be the cause? Maybe the tape held the blown cap in place so that the Quadra would have worked years ago...
- What can I do to permanently fix the damage? What cap is needed as a replacement? Can I just replace it with a wire (cap is not really needed maybe)? Do we have schematics for the Quadra 650?
It identifies as a Q650 and not a Q800 though..
