RD53 failure modes
Carlos E Murillo-Sanchez
ce.murillosanchez at gmail.com
Thu Feb 6 23:22:28 CST 2020
Hello folks;
I've recently had some free time and decided to look at some hardware
failures in my small collection. I fixed a couple of analog boards in
the compact Mac department, and a failed scsi disk in one of them
prompted me to test the small stash of such drives that I have. Turns
out, about half of those marked as "working" in 2015 have failed now in
many different ways. Oh well... sucks, but it was to be expected...
I decided to image some of the still working ones, both in the stash and
in working machines. The one in the vaxstation 2000 (a 1GB scsi with
5.5-2) turned out to have file system corruption (probably from AC
power failures), which has taken a while to fix. And then, I remembered
that said system originally came with an RD53 that has sat elsewhere for
25 years. It passed a read test in 2005. So I tried to see if I could
read it and maybe image it now, but no go. The disk spins up, initiates
a seek (the arm is not stuck in a gooey stop pad; I've read that this is
a common failure mechanism for Micropolis 1325's; I opened it and saw
the arm move) but then the arm returns violently (clacking) to the rest
position; it does this a number of times (two to four, usually) and then
it spins down. Applied voltages and currents remain ok as this happens.
I've seen plenty of internet content about solving the stuck arm
problem, but not this.
Advice, please?
Carlos.
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