PDP11 adventures

Curtis H. Wilbar Jr. rescue at hawkmountain.net
Thu Dec 7 22:57:10 CST 2006


Seth J. Morabito wrote:
> On Thu, Dec 07, 2006 at 07:20:05PM +0000, Adrian Graham wrote:
>   
>> On 6/12/06 22:27, "Gordon JC Pearce" <gordon at gjcp.net> wrote:
>>
>>     
>>>> Indeed, it looks like the original boot drive (also an RD53) long gave up
>>>> the ghost, which is a shame because it had RT11 5.4 and one of the systems I
>>>> wrote in the 1980's......
>>>>         
>>> What actually fails in them?
>>>       
>> Head actuator I think; it powers up and spins up, doesn't sound headcrashed
>> but I can't hear or feel the heads move.....
>>     
>
> Definitely check for stiction, it's a very common problem on RD53s.  If
> the data on them is worth saving, you can probably make a clean enough
> environment in your home or office to open up the drive assembly and
> nudge the head loose from the sticky rubber that it's parked against.
> You can probably get at least one good read out of it without it
> crashing (I know folks who've opened up their RD53s, reassembled them,
> and run them successfully for months afterward.  YMMV!)
>   

Stiction, as I've eperienced it (Quantum 100Meg drives as used in Suns), 
keeps the
drive motor from spinning up the disk (because the heads are stuck to 
the disk).

His drive spins up... he just doesn't hear the heads move...  which 
would lead me to
believe:

1. The problem I've seen with the rubber bumper out of adjustment
2. rubber bumper has gone sticky... and the heads can't move off of it 
(in which case
    it could be cured like head/platter stiction)
3. failure of PCB to operate head actuator voice coil...  this would 
require a replacement
    drive PCB.

-- Curt

> -Seth
>   




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