Re: IIgs MB repair info

["Jason Whorton" <jason at microxl.com>]

Will it boot without the floppy drive connected?  I see you have a "known
good" power supply.  Are you using a "known good" floppy drive?  Have you
tried to flex the motherboard a little while it was on?

Hope this helps,
Jason Whorton, A+ Certified Technician



"Bill Garber" <willy46pa@comcast.net> wrote in message
n5acnb5r9IIonpaiXTWJhw@comcast.com">news:n5acnb5r9IIonpaiXTWJhw@comcast.com...
>
> > If I remember correctly (and that's a *big* if), the drives are supposed
> to
> > start the spin-up cycle as soon as power is applied, whether or not the
> > motherboard starts talking.  The 'grunt' from the drive sounds like one
of
> > the voltage lines from the power supply is no good.
>
> Hoped everyone would realize power supply has already been ruled out.
>
> > That could either be due to a bad power supply or a short on the board.
I
> > would suggest:
> > 1) bench the power supply and check the voltage of each power line while
> > driving a test load
> > 2) remove any peripheral cards in case one is misaligned
> > 3) also disconnect any 'unnecessary' peripherals in case, for example,
> > somebody mis-indexed a pin when the drives were plugged
> > and if that doesn't turn anything up:
> > 4) try a different power supply.
>
> Running a bare board with drive on smart port, no cards, power supply
> is known good. Short on the board is suspected, hoped someone would
> have an idea which area on the board to zero in on.
>
> > The most likely failure modes:
> > #1:  90% - something is misaligned such as a Disk II cable connection or
a
> > socketed chip
> > #2:  9% - bad power supply
> > #3:  1% - failure of one of the unsocketed chips (expressly assuming
that
> > all socketed chips are 100%)
> >
> > Problem #3 is far more likely to occur in combination with #1 than by
> > itself.
>
> Yes, I assume the same is most likely. Anyone with an idea which
> area to pinpoint would help tremendously. Of course at $5-$20 for
> a IIgs CPU with PS, it may be time to just dump this one and get a
> replacement. I like to mess with them though.
>
> > Post-infancy chip failure usually does not occur unless induced by an
> > electrical short circuit.  I've seen #3 occur only twice, once when
> somebody
> > was hot-plugging peripheral cards on the bus and once when a defective
> > peripheral cable shorted the power supply.
>
> I agree, there definitely was some careless activity going on here, not by
> me, this GS came to me this way. ;-)
> Thanks.
>
> Bill @ GarberStreet Enterprises };-)
> Web Site - http://garberstreet.netfirms.com
> Email - willy46pa@comcast.net
>
>
>
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