Mac Plus is constantly rebooting!
Tae Shin
among two of the Mac Pluses. The symptoms are similar enough that they
may be related.
Basically, the Mac Pluses are constantly rebooting themselves, as if the
reboot button were being pushed. Sometimes the Mac is able to fully boot
and display the desktop, but it is only a matter of time before it reboots
again. At times, the frequency is as high as several times a minute.
Does anyone have any ideas on what might be happening, or has anyone had a
similar problem? We've removed the programmer's external switch in case
it was stuck, but to no avail. Swapping motherboards with another Mac
Plus showed that the problem is with that board, but that's as far as
we've been able to narrow it down. The computers are Mac Pluses with 2Mb
RAM and both have external 20MB hard drives.
Any help or suggestions would be greatly appreciated.
T.B. Shin
ts...@husc8.harvard.edu
Russ Hodes
:
: Basically, the Mac Pluses are constantly rebooting themselves, as if the
: reboot button were being pushed. Sometimes the Mac is able to fully boot
: and display the desktop, but it is only a matter of time before it reboots
: again. At times, the frequency is as high as several times a minute.
I wonder if your Mac has those little "RESET / INTERUPT" switches
installed. They are plastic devices that push on the switches which
are inside the mac. Or mabey those switches are bad and need replacing.
Celeste
An alternative problem with solution. Has happend to me twice on two
different Mac Plus.
The connector cable between the logic and power supply board
gets a little corrosion on it with age. This cause the voltage
drop between the powersupply and the logic board.
Quick fix #1. Simply un-plug and replug both ends of the cable.
If that does not work. Take the end of a flat bladed screw driver
and gently scrape the pin surfaces. You only realy have to
do the ground and +5 pins but I don't remember which ones
they are off hand.
That has worked for me a couple of time.
Celeste
t...@engr.latech.edu
things to each one and they all work fine. In one instance, there was a
cracked solder joint on the analog board - easy fix. Check the solder
joints on the board. Another was the previously posted connector cable
problem. On two machines we had to do an upgrade to the analog board. We
got an Analog Upgrade Kit from Computer Component Source, Inc. at
1-800-356-1227 for around $23. The kits are available for the Mac Plus
and the Mac SE/SE30, so specify for the Plus. That worked for the two
machines we did that to.
On a side note, has anyone ever had a Mac Plus "smoke out" on them? We
have had four machines that all of a sudden start emitting a thick grayish
white smoke. In each case it was a capacitor that had gone bad. Has
anyone else encountered this?
Good luck with the rebooting though.
- Keith
________________________________________________________________________
Keith Cooley
EE Macintosh Lab Administrator
Louisiana Tech University
Ruston, LA 71272
t...@engr.LaTech.EDU
Jeff Hite
This problem is usually a low +5 Vdc from the power supply, there is an
adjustment for this on the supply. If the voltage is still unstable or low
then the culprit is probably a bad rectifier at CR20.
Jeff Hite
Computing Center
U of Oregon
je...@ludwig.cc.uoregon.edu
Jerry Stubbs
>have had four machines that all of a sudden start emitting a thick grayish
>white smoke. In each case it was a capacitor that had gone bad. Has
>anyone else encountered this?
>Keith Cooley
>EE Macintosh Lab Administrator
>Louisiana Tech University
We've had it happen a time or two. Beginning students think it is pretty
entertaining when it happens during a lab lecture or demonstration.
Geoff Peters
I wish I caught the original post, but anyway ...
The problem is that the Plus's poor old power supply (sometimes referred to as
the analog sweep board) is on its way out. Apart from a board swap (bikkies to
Apple), there's not much the average Joe can do to fix it.
You can, of course, try and re-adjust the voltage levels (the 5v rail should
be as close to 5v as you cn get it) but this is more often than not a
temporary fix. A copy of Larry Pina's "Macntosh Repair & Upgrade Secrets" is a
worthwhile investment for the serious do-it-yaself-er.
Geoff Peters mid...@cola.flash.pax.tpa.com.au
george
:> : Basically, the Mac Pluses are constantly rebooting themselves, as if the
:> : reboot button were being pushed. Sometimes the Mac is able to fully boot
:
well this threads been going long enough... I'll add a diferent twist.
I found that the constant rebooting was due to overheating. We
had added 4Mb ram, and were operating in a non AC environment.
Adding an external cooling fan fixed it right up. ( over a
year ago )
--
/ george jefferson
\/ * geo...@mech.seas.upenn.edu
Karl Johan Olsen
wrote:
>
> :> :
> :> : Basically, the Mac Pluses are constantly rebooting themselves, as if the
> :> : reboot button were being pushed. Sometimes the Mac is able to fully boot
> :
>
> well this threads been going long enough... I'll add a diferent twist.
>
I'm expiriencing the same kind of problem with my SE (2.5/40), although not
as frequent.
Any suggestions?
------------------------------------------------------------------------
Karl Johan Olsen Internet: kar...@imv.aau.dk
Dept. of Information and Media Science
University of Aarhus
Denmark