Notes on repairing the Apple Lisa power supply

From: Joe <rigdonj_at_intellistar.net>
Date: Thu May 25 14:58:48 2000

I have a Lisa 2/5 that doesn't want to work. Here's some things that I've
found out in the process of troubleshooting it.

  (1) The PS in the 2/5 and the 2/10 are interchangeable but the 2/5 PS has
a lower capacity. (2/10 and the Mac XL hardware are the same).

  (2) The card cage must be installed in a before the PS will turn on but
the memory and I/O cards need not be installed.

  (3) The CPU does not have to be installed for the PS to work but if it's
not installed the PS will keep resetting and will make a chirping sound.

 (4) The card cages for the 2/5 and 2/10 have different brackets and don't
appear to be interchangeable.

 (5) An I/O card from a 2/10 will work in a 2/5, at least properly enough
to power it on and get a display.

>(6) A "bad" I/O card in a 2/5 will prevent the PS from turning on and will
cause the PS to appear defective.< (see note 2!)

    My 2/5 will not power on. I installed a known good PS from a 2/10 and
it still doesn't work. The 2/5 PS DOES work in the 2/10 so it is good. The
2/5 will power up with an I/O board from a 2/10 or with no I/O board
installed so the problem appears to be in the I/O board. The battery
condition seems to not matter. Does anyone have a schematic of the
interlocks and interconnects for the Lisa 2/5 or know what signals the
power supply gets from the I/O board?

    Joe
Received on Thu May 25 2000 - 14:58:48 BST

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