Re: PowerMac problems-Help!

Bruce Carter (bcarter@mentor.idbsu.edu)
Wed, 17 Apr 1996 18:16:30 EDT

At 12:17 AM 4/17/96, Michele Oyster wrote:
>Please help! My Power Macintosh 8100/100AV has some serious problems. It
>crashes (freezes) quite frequently when I am doing nothing in particular.
>In fact, I might not even be using it at all when it crashes.
>
>The same thing occurs each time, but I don't know how promising that is to
>someone trying to find the solution:
>Option + Apple + Escape does nothing. Control + command + restart shuts it
>down completely, and then the computer will not boot up using the power
>button on the keyboard...even if left off overnight. In fact, it won't
>start up at all until I unplug it and plug it back in. I worked with
>someone here to reinstall the system software after a crash that left me
>with a sad mac, a black screen and some 0000000F and 00000000D. We
>upgraded to system 7.5.3 from 7.5.1. However, the same type of crash
>occured 2 or 3 days after the new system install. I have not installed
>anything new since the system upgrade. Norton finds no big problems, and
>my pram has been zapped. Have any of you experienced such a phenomena? We
>are now checking into the possibility of replacing the mother board....

I have an 8100/100av at home as well, but I haven't seen this problem. One
thing you can try is to open the case and make sure the AV card is seated
properly. It's kind of a funny fit in the PDS slot in the 8100 case, and
there is a bit of pressure from the metal "fingers" along the back of the
machine.

You should also check your SIMMs and make sure they are all seated and
within specs for an 8100. They need to be installed in pairs of the same
size and speed, from the low slots to the high slots. You may want to have
a technician do this as it involves disassembling the computer to some
extent (on the other hand, I've done it several times with no ill effects
other than a scraped knuckle from a chip leg... *heh*. If you do it
yourself, though, make sure to get and use a grounding strap.).

Check the voltage on the backup battery, if it's low, replace it.

Check the reliability and termination of your hard drive. The 8100 has two
SCSI busses, which can mean double the amount of SCSI voodoo you may need
to perform to track things down. Generally, the internal hard drive is the
only thing on the SCSI 0 bus. The SCSI 1 bus runs the internal CD-ROM (if
present), the internal tape unit (if present) or whatever else is in the
internal bays as well as any devices hooked up to the external SCSI
connector.

If you do take it in to a technician, have him/her check the cooling on the
CPU. There is a large heat sink, a big fan, and a thermocouple that need
to be in place for reliable operation (and people joke about Pentiums
getting hot).

The "won't turn on unless you unplug it" symptom I have seen, but on
Macintosh IIcx and IIci systems. In all of those instances, the solution
was to replace the power supply module.

--
Bruce Carter, Instructional Software Designer     (208)385-1851@voice
Boise State University, Boise, ID  83725          (208)385-1856@fax
http://mentor.idbsu.edu/BruceCarter/home.html     bcarter@mentor.idbsu.edu