I had one of these drives that behaved this way. As I figured I had nothing
to lose, I opened it op and watched it operate....
The theory I came to was that the stopper material changed dimension with
age and the drive could not get to track zero.
I loosened the stopper and ever so slightly (2-3? thousandths of an inch ?)
to let the heads further outward (as I recall).
After doing that and reassembling.... it worked fine.
I did not put a lot of 'miles' on the disk after that.... I had already
different disk in service... but for the time I used/recovered
it powered up 100% every time after that 'repair'.
I can't say if my theory is right.... and it could have been just dumb
but I thought I'd relay what I did... as if you don't get it to function
any other way
you don't stand much to lose by trying it.
I believe I've read talk on here about homemade 'clean rooms' ....
less dust/particulate matter you get in the drive the better the chances
Rob Jarratt wrote:
I have posted before about an RD53 I am trying to get
back to working order.
After unsticking the heads I thought I had a working disk as I have been
able to format it and do an image restore of the VMS installation media to
it. However, intermittently it has been failing. When this happens the heads
completely fail to move when I power on the disk, so the controller and
firmware cannot even determine its size. After a few moments the disk spins
down. As I said, this is intermittent, sometimes it will work OK.
A friend has been helping me and he gave me a complete set of the three
boards in the RD53 from a known working disk (he can't give me the disk for
reasons not worth going into). I changed all three boards and the drive
still completely fails to move the heads, in fact now the fault seems
permanent. My friend suggested that the positioning coil may be faulty. He
measured the resistance of the coil on one of his working disks (at the plug
that goes to the coil from the motor control board), it came to 3 ohms, mine
also measured 3 ohms. I measured the voltage at the plug going to the coil,
one reads 2V the other 3V, but when it works they both go to about 5V.
Can anyone suggest what might be the problem?