18 Apr
2010
18 Apr
'10
11:54 a.m.
On Apr 18, 2010, at 10:34 AM, Tony Duell wrote:
0.8" = 20.32mm Maybe the exact size is 20mm. Although I would normally
expect imperial measurements in an American device, I have noticed that
all the screws in this drive have metric threads. So perhaps it is a
sensible diameter in milimetres.
the overall diameter of the tyre is perhaps 18mm
(it's going to be
hard to measure, sure the fact I don't have a
solid one :-()
I put a micrometer on the capstan in my 9145A. It had turned to goo,
but not melted yet---so it was intact, but difficult to measure
without deforming. I got a reasonably accurate measurement off it.
Based on experience, this should be close enough to affect a workable
repair (though I haven't gotten to actually doing the repair yet).
HP 9145A 36 Track < 0.800"
That should be read as "just under 0.8 inch."
It was actually harder to clean all the melted capstan residue off the
motor spindle than it was to measure it in the first place. It gets
EVERYWHERE.
Indeed. The place to keep it well away from is the slotted tachomter disk
also on the motor spinde.
My method for cleaning invovles a bit of dismantling. Take off the top
cover and front pneal. Unclip and remove the tape door and its torsion
spriong. Remove the cotnroller board (athe tope of the unit), then the 4
screws on the bottom and take the drive mechanism out. Remove the
board(s) from the underside of the sdrive mechanism.
Take off the microswitch assembly (2 screws, but make sure you know which
switch goes on top!). Remvoe the optical BOT/EOPT sensor in a 9142. This
is not essentla but it's fewer things to get gunged up.
Now turn the drive ipside down. See the little plastic part in front of
the mtoor that hoos into the loading mechanism. Remove this (2 screws),
then loosen (or remove) the 2 setscrews holding the motor pivot spindles
in place. Slite out the spidles and lift out the motor assemlby. Recover
the spirng and 3 insulating bushes. Note that hte motor is insulated from
the drive chassis (the drive chassis is connected to logic groudn, the
motor to power groudn, these are connected in the PSU only). Remove the
tacho senso from the motor (1 screw).
Now clean off as much of the gunge as you can using kitchen paper and
propan-2-0;. Start with dry paper (it will remove much of the gunge),
then clean up witht he alcohol. Then connect the motor to a bench supply
anf give it about 12V (it's not critical). You can now clean it using
paper or cotton buds dipped in propan-2-ol. You won't get it perfect, but
it comes a lot cleaner that way.
-tony