dr@ski.UUCP (David Robins) (11/19/86)
In several published articles, Apple Duodisks have been said to eat
disks if certain copy protection schemes are used.
I had heard Apple was ugrading or exchanging the affected units, so I
got in touch with an Apple service dealer. They are upgrading only-
not exchanging. The unit serial number is not a good indication of if
a certain unit is affected. (apple fixed this problem around October,
1984).
You need to look at the top board in the left (#1) drive.
According to Open-Apple Vol1,#12,Jan'86, the board number of affected
boards begins with 676 and ends with either 101 or 102.
(Unfortunately, the affected units can therefore only be identified by
remving the case, and opening the top cover on the drive.)
The fix consists of removing (clipping off) 2 capacitors on this
board. The printing on the board identifies them: C29 & C30.
They are in the lower right-hand corner area.
I was also told that some drives are destroying disks due to a problem
with the 74LS125 chip on this same board. Since it is a plug-in item,
and cheap, I see no reason not to do this replacement at the same
time.
BTW: since this modification is usually done by the dealer, I don't
know how it would affect future dealings with apple about the drive.
Since these older units are out of warrantee anyway, I personally did
not hesitate in doing this on my own. (A dealer fix means taking the
drive in, and leaving it for a few days, usually.) If you screw it
up, you're on you own - I cannot take responsibility for this
information. I have a high level of confidence in its accuracy,
though, because I got the same info from techs at 2 different
dealers.
--
====================================================================
David Robins, M.D.
Smith-Kettlewell Eye Research Foundation
(previously known as: Smith-Kettlewell Institute of Visual Sciences)
2232 Webster St; San Francisco CA 94115
415/561-1705 (voice)
{ihnp4,qantel,dual}!ptsfa!ski!dr
The opinions expressed herein do not reflect the opinion of the Institute!