Shugart 800-8 media centering problem

Jay Jaeger cube1 at
Sat Aug 15 15:13:09 CDT 2015

On 8/15/2015 1:55 PM, tony duell wrote:

>> Certainly one of my thoughts along the way.  But, the spindle cone does
>> not rock or anything like that.  And, I switched the clamping part out
>> with another drive - neither was affected by the swap.
> It strikes me that there are 3 main subassemblies associated with clamping the disk : 
> The cone; the clamping arm; and the spindle. If you have proved the first 2 are OK by
> using them in another drive (admittedly not a perfect test, but it suggests they are not
> the problem) then I would look very carefully at the spindle.
> Making a replacement cone is possible, but not easy, given the accuracy needed. It
> appears that the spindle in my drive is in 2 parts, the cone is pressed onto the end of
> a metal spindle. I think if I had to make it, I would make the spindle rod first, rough out 
> the blank for the cone, leaving it well over size  then press the  blank for the cone onto
> the end, hold the spindle in a collet (a 3 jaw chuck is nowhere near accurate enough) 
> and then turn the cone itself. 
> -tony

I think if I had to make it, I'd just find another drive. ;)

To make matters worse, that test with the first SA 801 managed to smoke
the 24V power supply on this system, so now I have to pull it all apart,
and pull out the regulator transistor which is mounted from the reverse
side through to the board and soldered on the top side of the board.
(possibly 3 of them, if that transistor isn't obviously the problem).  A
royal pain in the arse.

So, there won't be any progress for quite a while.  Maybe months.


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