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Mac IIci Won't Stay On (a long time)

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#1 ajacocks

  • 6502

Posted 22 November 2011 - 08:31 PM

So, I seem to have the common IIci issue of the machine spontaneously shutting down. Mine is configured, as follows:

System 7.5.5
128mb RAM
2gb Quantum Grand Prix 7200rpm
Radius PrecisionColor Pro 24x
AsanteFast 10/100
FWB JackHammer, currently connected to nothing

I had assumed that the problem was either the PRAM battery, or the PSU. So, when replacing the PRAM battery did nothing, I replaced the PSU with a known-good unit from a 7100, to make sure that I had sufficient VA. Neither seems to have done the trick.

In my case, it does take quite a while for the machine to decide to spontaneously power off. It's usually over an hour, which is about the time that I always think I've fixed the problem.

I don't see any obvious failed caps on the board, but I'm not an expert.

Any ideas?

- Alex

#2 Scott Baret

Scott Baret
  • 68LC040
  • LocationPittsburgh, PA

Posted 23 November 2011 - 03:35 AM

You have bad capacitors. I had the same problem on my IIci and swapped PSUs twice, neither of which were able to solve the problem (both were known good PSUs). Some of the folks on here said it was likely capacitor-related. My IIci's board is actually out being re-capped right now thanks to one of our forum members, which evidently will solve the problem.

You should be fortunate your IIci lasted an hour. Mine was lucky to go 30 seconds before I sent the board off.
"Education is life."

#3 ajacocks

  • 6502

Posted 23 November 2011 - 02:40 PM

Yeah, I had a feeling it was that.

My IIx suffers from a similar issue, but it turns off much more quickly. Would you be willing to share the name of the MLA member who is recapping yours? I'd love to pay someone to recap my two boards.

- Alex

#4 AppleMacintosh

  • 6502

Posted 26 November 2011 - 04:30 AM

I'd venture to say this is due to the caps controlling the on/off switch. I have noticed that my IIci (before recapping) doesn't respond to the power switch at all. It doesn't spontaneously turn off, but it remains on all the time and can't be switched off without unplugging it. I noticed several bad caps right in the vicinity of the power pushbutton on the rear of the logic board. I've removed all the caps and am waiting on a new set from trag. I'll try and remember to post if this fixes the power issue for me.

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