Common Maxtor MFM drive failure mode -- any ideas?

[Joseph Lang]

If the bumper is there it will be on the side wall of the HDA where the head actuator would touch when retracted. 
If the heads move freely you have a driver failure. the scream is the stepper motor trying to move with only one phase working. (Also a common drive failure.)

Joe

> On Oct 23, 2015, at 4:26 AM, Josh Dersch <derschjo at gmail.com> wrote:
> 
>> On 10/23/15 1:19 AM, Joseph Lang wrote:
>> There is a plastic bumper in the head/disk assembly that turns to goo.
>> When the head retracts it hits the bumper and gets stuck in the goo. The goo will eventually win. The head will no longer load. I can't say For sure this is your disk problem but it was a verry common Maxtor failure.
> 
> I thought that was true for Micropolis drives (like the DEC RD53, a Micropolis 1325/1335) -- or does the Maxtor have a rubber bumper as well?  As I said I had one open and the heads were not stuck (I could move them with my finger -- while the drive was spinning of course :)) and I didn't notice any goo-laden parts, but maybe I wasn't looking in the right place...
> 
> - Josh
> 
>> 
>> Joe
>> 
>>> On Oct 23, 2015, at 3:04 AM, Josh Dersch <derschjo at gmail.com> wrote:
>>> 
>>> Hi all --
>>> 
>>> I acquired a Symbolics 3640 today and it came equipped with two "large" capacity Maxtor MFM drives (an XT-1140 and an XT-2190).  The 1140 spins up fine and we were able to image it using Dave Gesswein's MFM emulator (yay).
>>> 
>>> The 2190 does not, and it fails in precisely the same way I've personally seen three or four other Maxtor drives of the same era fail:  It spins up fine, but when it goes to load the heads, it sounds like the voice coil positioner for the heads is "screaming" -- it emits a high-pitched, quite loud whine/buzz which persists until you power the drive down.  The drive is unresponsive during this time.
>>> 
>>> I'm fairly sure it's not a head crash or anything like that; having gone through this a year or so ago with a similar drive that was scratch anyway, I opened it up and verified that the heads weren't stuck, and I see no evidence of a head crash after disassembly.
>>> 
>>> Further, the fault does not appear to be on the logic board -- we swapped in a board from a working 2190 tonight and afterwards the drive exhibited the same symptoms.
>>> 
>>> I've had this happen to other 2190s and 1140s and a few of the ESDI drives in the same family, some of which were working in my possession for weeks before failing -- has anyone else seen this? Any ideas?  I'd kind of like to recover the data off of the 2190 from the 3640... drat.
>>> 
>>> Thanks,
>>> Josh
>