RD54 Stopped Spinning

Jon Elson elson at pico-systems.com
Fri Apr 3 12:41:56 CDT 2015

On 04/03/2015 12:06 PM, Robert Jarratt wrote:
> Yes, it is 6 transistors. All this sounds like I am going 
> to have to open up the disk to get inside as the motor is 
> on the inside. I don't think there is a way to turn the 
> spindle without opening it.
Some of the older disks in this vintage had the motor 
outside the HDA, and there was a little fan on the end of 
the motor that cooled the heat sinks, etc.  You could see it 
by folding the PC board away from the bottom of the drive.
I thought the RD54 was from that family, but I might be 
remembering an older drive (RD53??)
> Interestingly at one point it started working again. Then 
> after I put it all back together again, it stopped working 
> once more. In one case, it seemed to start spinning when I 
> changed the disk's orientation (on its side rather than 
> flat), almost as if it just needed a mechanical 
> encouragement to get it moving. But now, no matter how 
> many times I try, and what different orientations I try, 
> it doesn't work. Does any of that help with pointing the 
> finger at all? Regards Rob 
Well, I'd try wiggling connectors some more and see if you 
can get it to spin up again.  Sticky motor bearings and 
stuck heads are common on older drives.  They put a landing 
lube on the park areas of some drives, and that eventually 
glued the heads to the disk, requiring more torque that the 
spindle drive was allowed to provide.

But, your drive spun down while running, which is not 
connected to that scenario.


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