This RD53 spindown problem can also be caused by a spindle brake that does
not retract fully when the drive is powered up! It rubs against the spindle
and the drive shuts down. I fixed this by simply undoing the screw holding
the brake solenoid and moving it back a little bit. My drive has been
running for well over a year following this fix.
Check this before opening the drive case!
Kevin
At 11:25 AM 97/11/09 -0500, you wrote:
><From: "Zane H. Healy" <healyzh_at_ix.netcom.com>
>
><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?
>
>Zane,
>
>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
>installed.
>
>
>Allison
>
>
>
>
---
Kevin McQuiggin VE7ZD
mcquiggi_at_sfu.ca
Received on Sun Nov 09 1997 - 12:18:51 GMT