Re: Baked Apple Drives?

[mjmahon@aol.com (Michael J. Mahon)]

In article <e639cb5b.0303240942.2cc28a9e@posting.google.com>,
twohandsfree@hotmail.com (John) writes:

>Last weekend I may have fried my disk drives on an Apple //e.  Are the
>drive toast?  Read below, please.
>
>  After a motherboard swap I fired it up, heard a tiny tiny pop,
>smelled smoke and got no disk activity. After swapping disk drives and
>controller cards I was able to boot up.
>
>  The cable's red wire and pin 1 were oriented correctly -- but
>perhaps it was off a row, or not in full electircal contact (or same
>with edge connector on board)?

A general rule is that if you can smell toast, you've made toast.  ;-)

BTW, are both drives fried, or only the one that was "off-by-one"?
And you should try the controller with a known-good drive (generally
a safe thing to do) to verify that the controller is still OK (it probably
is).  In short, this error should have resulted in only one drive being
toasted unless you plugged _both_ of them in wrong.

The "off-by-one" syndrome usually results in the destruction of a
chip on the Disk ][ analog card.  The chip is usually socketed (as
they all are) and it should be obvious which one is "toasted".
I have a fleeting recollection that it is a 74LS125.  (And it would
be pure luck if I happened to remember that without checking.  ;-)

These chips are still available very inexpensively, with Radio Shack
being, perhaps, the most expensive but most widely available source.

Good luck!

-michael

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