On Thu, 25 May 2000, Joe wrote:
> 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.
Weierd, I could have sworn I just read the words "process of
troubleshooting" above; I'd better get my eyes checked.
> (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.
Did you test the power supply with a dUmmy load first, using a
voltmeter as well as an oscilloscope to check for voltage levels, as
well as spikes, before applying power to the boards, and applying any
necessary test connections to the PSU's input connectors?
> (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.
"properly enough"?
> >(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!)
Don't you mean an I/O card with a short circuit somewhere? If you
don't know what a short circuit is, just ask, or experiment... e.g.,
if, for example, you touch the conductors connected to the hot and
ground connectors of a mains socket, and a fuse blows or a circuit
breaker trips, you'll find that you've learned a lot about short
circuits and saving classic computers. ;-)
> 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
Surely you jest...
They why did you risk swapping in another un-tested, even though
thought to be good, PSU, and risk additional damage to the boards?
Didn't you test the 2/5 PSU before doing anything else? Why put the
2/10 at risk by putting a PSU in suspect condition into it?
Hmmm... have you considered computer preservation as a hobby instead
of computer demolition?
> 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?
Shouldn't you have tried to find that out before swapping things
around without knowing what you were doing?
--
R. D. Davis
rdd_at_perqlogic.com
http://www.perqlogic.com/rdd
410-744-4900
Received on Thu May 25 2000 - 15:34:27 BST