RL drive lubrication

J Blaser oldcpu at rogerwilco.org
Tue Apr 11 14:41:26 CDT 2006


Tony Duell wrote:
>> for power supply checkout, I went ahead and removed the brush assemblies.
>>     
>
> What did you remoce? Just the brush tips? Did you leave the motor, the 
> microswitch, and the operating cam? Without those, you might have 
> problems getting the drive to go ready.
>
>   
Yes, I left the motor, cam, and switch.  I just removed the actual brush 
arm from the shaft, leaving everything else so that the logic would 
'think' the brush is still in place.

>>  
>> Fortunately, the 'clean' set of drives are now fully functional, having 
>> been tested
>> with one of the 11/23s.
>>  
>> Unfortunately, after mounting and LOADing a known good disk cartridge, 
>> neither drive
>> from the 'dirty' set will show READY after spinup.  Though the details 
>>     
>
> You do have these cabled to a working controller, I trust? You need the 
> clock signal from the cotnroller for the drive to spin up and go ready.
>   
Yes, indeed, I'm using the same platform for my testing of all drives -- 
both the dirty drives that are 'broken', and the clean set that work -- 
with every other component except the drive being the same.  That is, 
I'm using the same 11/23, RLV11 controller, cables, terminator, etc.  
I'm just swapping the drives themselves.
>
>> I wonder if dragging bearings are preventing 
>> the drive from
>> becoming READY due to uneven RPM?
>>     
>
> It's possible, but unlikely. I suppose you could start by looking at the 
> output of the sector transducer (posibly after the amplifier circuit). 
> That's what the drive uses as a speed reference anyway (the motor in the 
> RL is not locked to the mains, unlike most other demountable hard drives, 
> there is no change for 50/60Hz). See if the signal is stable and has the 
> right frequency (compare it with the same signal in another working drive).
>   
Excellent advice.  I will try this.  I do have a scope, though I'm more 
of a software geek rather than a hardware engineer!  :)  I just find it 
interesting that both of these drives (the 'dirty' set) exhibit the same 
behavior vs. the 'clean' set, when all else is the same, i.e., 
controller, etc.  I may be fixating on the noise as the cause of no 
READY indication, but maybe it's something else.
>   
> I would not try to lubricate the spindle bearings. You'll never get it 
> apart anyway (t's pressed together, and you have to maintain mecahnical 
> balance, etc. There may be a ferrofluid seal in there too). The risk of 
> contamination to the disk/heads is too great. 
>
>   
Hmm...okay.   I'll let this go for now, hoping that the issue is with 
the motor.
> It shouldn't hurt to take the spindle motor out, take it apart (obvious 
> through-bolts) and oil the bearings. I think they're phosphor-bronze 
> bushes, not ball races, in which case you want a medium machine oil on them.
>
>   
I'll begin here, and see if this resolves the noises I'm hearing.  I 
still hope that IF the lubrication helps to steady the RPM, it might let 
the drives go READY.
> No, you can remove and replace the spindle without upseting the heads. In 
> any case, the RL drive has an embedded servo burst in each sector header, 
> so head alignemnt is quite easy (you need a 'scope, but no special 
> alignment disk, any normal disk will do).
>
>   
I was just worried that there might be some vertical alignment issues if 
the spindle assembly wasn't put back correctly.  I have no idea if there 
are shimming or 'leveling' screws that would assist in making sure that 
the platter is aligned vertically (along its axis) so that the heads 
have the proper 'flying height' for both surfaces of the platter.

Many thanks, Tony, for you suggestions.  I'll let you know how it goes, 
probably later in the week.  I've gotta satisfy the tax man first!  
April 17 is fast approaching!  :)

J.




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