22284How can I tell if my SMD disk head is crashing?
- Aug 11, 2011I've been working for a while on reviving/rehabilitating an old CDC 9762 disk drive (each disk is a stack of 5 14" platters, with the middle 3 having 5 data surfaces and 1 servo surfaces - the drive has 6 read heads). I finally got to the point where the drive was cleaned up, so I spun up a disk pack and manually loaded the heads by just disconnecting the servo coil and moving it with my hand (the manual says this is okay for testing).
When I loaded it, everything was fine for a minute or so, but then I began to notice a high-pitched whining noise coming out of the drive. I retracted the head assembly, stopped the disk, and attempted to inspect it and the head assembly. Everything looked fine as far as I can tell (the disk is a bit difficult to examine, as you need to look at it through the tinted plastic of its cover). I then retried the same procedure, and the high pitched whining noise started again right away when I loaded the heads.
Does anyone know if that noise means one or more of the read heads is contacting the disk? Or could it just be a whistling noise produced by the head being close to the surface? The disk cabinet had been lined with a thick layer of noise-deadening foam that I had to remove, and I've never really worked with one of these before, so I'm not sure what it's supposed to sound like. Any advice would be appreciated.
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