25 Jul
2013
25 Jul
'13
2:28 p.m.
-----Oorspronkelijk bericht-----
Van: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org]
Namens Tony Duell
Verzonden: donderdag 25 juli 2013 21:58
Aan: cctalk at classiccmp.org
Onderwerp: Re: HP 7906 spindle motor repair ??
>
> > Well, our drives made terrible noises when they spun up the first
> > time after many years. My first thought was bad bearings (singing
> > and screaking like old HDDs), but otherwise the drives worked fine,
> > so I just ignored (and somehow even enjoyed ;-)) the noise. But the
> > noise went away after a few hours of running, so I think the
> > bearings (the grease or
> > whatever) have "recovered" from sitting there unused for such a long
time.
> > But it may be possible that you really have
bad bearings or a bad
motor.
I am totally cleueless about THOSE drives, but, 25+ years ago, a lot
of
So am I.
I looked at the information on the Australian museum site. When I looked he photos of the drive with the covers off I saw a
normal-looking
induction
motor alongisde the disk housing nad thought
'what's the problem, jsut
remove
the through-bolts nad it'll come apart'. Alas
upon reading the manual i
realised
that this was the blower motor and that the spindle is
driectly driven by
a
brushless DC motor.
And now a word of warning. Those spindle assemblies are not designed to
come
apaert. They will ahve been assembled with a press
using special die
tools. There
may not even be a a way to strip it without damaging
some paet (that is,
theyre
may be no way to apply the force needed where it is
needed). Certainly the
belt-
driven spindles in some older drives are like that.
The next thing is that there may well be a dust seal in the assembly. And
it
woun't be a conventional seal, it could well be a
special magnet keepign a
ferrofluid between the housing and the shaft. Sorting that out could prove
'interesting' too.
-tony
On Christians advice I let the disc run for a few hours, at first without
the disc pack later with a disc pack in place.
After some time the noise faded away, and the spindle motor is running fine
now, it makes some noise but no vibration any more.
Next thing to do is inspecting the platters for corrosion and other nasty
things..
So at this time I'm not going to dismantle a spindle motor..
-Rik