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Re: Rev 4 mobo disk trashing mystery



schmidtd wrote:
On Apr 23, 9:48 am, "RedskullDC" <R...@oz.org> wrote:

If you get this far, check the rails coming out of the power supply
(particularly 12V)
when it is under load.

Ah, and I did get that far.  I think you've hit on the problem.  I was
using an IIe power supply I got from eBay some time ago.  I was
assuming it was good, and using that on the bench while testing the
board and disk.  Once inside its case, it got to use its original
power supply - which miraculously cured all that ailed it.  (Except
for the pesky sticky "5" key...)

Hmmm!

I should mention that I've got a //e that's acting quite similar to
yours--trashing random spirals on the disk when writing, though it
reads just fine--and I've been noticing a correlation with the video
level dropping as viewed on a monitor--which is a function of +12v.

I'd just made a note to myself to hang a scope on the +12v to see
what happens to it...   ;-)

-michael

NadaNet networking for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
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