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- From: jeh@cmkrnl.com
- Newsgroups: comp.sys.dec
- Subject: Re: RD53s won't stay spun-up
- Message-ID: <1993Jan5.042039.1070@cmkrnl.com>
- Date: 5 Jan 93 12:20:39 GMT
- References: <1993Jan2.160631.1058@cmkrnl.com> <C0AGzD.GtH@watdragon.uwaterloo.ca>
- Organization: Kernel Mode Consulting, San Diego, CA
- Lines: 45
-
- In article <C0AGzD.GtH@watdragon.uwaterloo.ca>,
- kcwellsc@watdragon.uwaterloo.ca (Ken Wellsch) writes:
- > You don't say anything about the history of the drives. We here at U of
- > Waterloo have loads of RD53's that have the same behavior. [...]
- > So my guess is you've received these drives with
- > this condition (i.e. they did the same in their DEC equipment as well
- > which maybe why you've now got them?)
-
- No, actually they were working fine on the RQDX3 controller some time ago.
- They were removed from service when I got one ESDI drive + Q-bus controller for
- essentially free, said ESDI drive being bigger and faster than all of the
- RDnn drives put together. They sat on the shelf for a few months. Very
- recently I've had a need to throw together some low-end PCs, and I had these
- drives, and I have pressed RD53's into PC service before...
-
- I'd suspect "stiction" or some such from the long "shelf time", except that
- one of these drives formatted successfully on the PC before acquiring this
- "won't stay spun-up" disease.
-
- > The current theory is this: these Micropolis 1325's and 1335's apparently
- > have quite sophisticated current sensing circuits to monitor the motor
- > load and such. With time, the motor windings degrade and the current
- > load exceeds the tolerance of the limiting circuit. The spin-up spin-down
- > behavior is the drive saying I am not working correctly.
- >
- > I've also heard about these puppy's having thermal troubles as well, they
- > run for a while then spin down. I think it may be a similar problem.
- >
- > Indeed as others have pointed out, they do draw a heck of a current normally
- > as well -- 2.5A as +12V normally.
-
- Thank you to EVERYONE for the information so far.
-
- (This is the sort of problem that's more annoying than I really have time for.
- 70 MB of disk for a PC just doesn't cost that much nowadays; I don't really
- *need* to use these big, power-hungry, slow drives... but now that this
- problem has surfaced, I want to understand it, if only so I can avoid it in the
- future!)
-
- --- Jamie Hanrahan, Kernel Mode Consulting, San Diego CA
- drivers, internals, networks, applications, and training for VMS and Windows-NT
- uucp 'g' protocol guru and release coordinator, VMSnet (DECUS uucp) W.G., and
- Chair, Programming and Internals Working Group, U.S. DECUS VMS Systems SIG
- Internet: jeh@cmkrnl.com, hanrahan@eisner.decus.org, or jeh@crash.cts.com
- Uucp: ...{crash,eisner,uunet}!cmkrnl!jeh
-