VAXstation II, now different problem

From: Allison J Parent <>
Date: Sun Nov 9 10:25:08 1997

<From: "Zane H. Healy" <>

<OK, now I've got the HD plugged in and am hoping things will go better.
<Foolish me. Now it just sits there on "2". Doesn't even give me the "?54
<RETRY" message, it simply sounds like it starts to spin down the HD, and
<then immediatly spins it back up. It's been sitting like this for a while
<now. Nothing. Even the LED on the back says "2".
<Oh, at least I found out I've got an RD53-A HD. Is there any difference
<between a RD53 HD and a RD53-A HD, or are they the same thing?


You have a bad RD53 like I said yesterday. The controller cannot/does not
command the drive to spin up/down as its an MFM drive. The cause for spin
down on RD53s is the head is not finding the servo track so it spins down
and retrys spinning up and finding the servo track. There is a fix for some
of them...

The problem on the Micropolus 1325s is the head meck when powered down
sits against a rubber bumper and gets stuck there as the rubber decays.
The result is the head can't move. Possible fix, open the HDA (yes take the
cover off) while running and move then head manually till it aquires the
servo, put the cover and backup to tape if there is an OS on it. I have one
drive where I put some sticky lable on the bumper to salvage the drive and
it's held up for six months so far. The bumper in located in the voice coil
positioner and is visible to the eye. The head arm sits agaisnt it when
powered down.

FYI: if you open it in a generally clean place ther is little risk of
contamination and even these "sealed" drives contain a internal air filter
to remove contaiminents.

Generally RD53s with spin down not reliable and should be replaced.

An RD53 is a microplus 1325 71mb MFM drive. For microvax use a RD54,
159mb MFM drive is more reliable an provides enough space. VMS will fit
on a RD53 if DECwindows and system libraries are not installed leaving
about 10mb free and makes for a cramped system. An RD54 will permit a
full VMS install and show have at least 20mb free making a very useable
system. A two drive system using a RD54 and an RD52(31mb), 53(71) or
RD54(159mb) for the second drive is a very good ssytem and can support
useful work.

FYII: A VS2000 (a tiny microvax) is handy as it contains rom code that
can format and/or verify MFM drives. They also make pretty good VMS or
Ultrix systems in their own right of they have at least 4mb of ram

Received on Sun Nov 09 1997 - 10:25:08 GMT

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