[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: IIe power supply problems
In article <ggonter-2906960026140001@port-50-max-btv-02.ramp.together.net>,
Geof Gonter <ggonter@together.net> wrote:
> I need a little help with a computer. I was given a IIe that would not
> run. I believe it to be with the power supply I was successful in getting
> the IIe to run, but there is a problem somewhere. The voltages check out
> pretty close on the power supply and it will boot, if you slide the power
> supply connector over the lugs and get the "Power On" light to come on. It
> will even stay on if you push the connector all the way on. But, once the
> power is cut, switch on power supply, pulling the plug, or turning off the
> surge protector, the unit will not power up until the connector is pulled
> and pushed down over the lugs in the connecting socket on the board.
This may indicate a fault on the motherboard, e.g. causing a power
supply short. The Apple II supply is a switch-mode supply, and is
designed to cut out if there is no load or too much load on it.
If there are any cards installed in the computer, remove them then try
turning it on. If it still doesn't work, and you can hear a regular "chirp"
noise from the supply, then there is probably a short or faulty chip
on the motherboard.
> Wiggling the connector plug has no effect on the whole thing. The voltages
> are:
> Terminal Should be- Reads-
> 3 +5.0 VDC +5.03 VDC
> 4 +12 VDC +11.79 VDC
> 5 -12 VDC -10.53 VDC
> 6 -5.0 VDC -4.57 VDC
They are all fine. 5V is the only critical one, and it should
normally be correct to within 2% (4.90 to 5.10 volts), preferably 1%.
The negative rails (-12V in particular) are much less critical, and
the numbers you've quoted are typical of supplies I've looked at.
+12V is usually around the +11.8V mark, so that is also fine.
--
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand