1 Dec
2009
1 Dec
'09
1 p.m.
There are
several versions of the mouse (different shapes, I think maye=
2=20
and 3 utton versions, and different circuits).
But I think they're all=20
pretty mcuh compatible.
The one shown in the 16500B manual looks like someone glued half a=20
tennis ball to the bottom edge of a cuboid then shoved a cable in the=20
other end... Very strange. What I need to hunt down now are some replacement
machine screws for the=20
mounting feet. Two of the feet have been removed; it looks like the=20
machine was dropped at some point in its life, and the mounting screws=20
have been snapped. On top of that, the square-profile metal tabs that=20
hold the screws have been split apart by the force of the impact.
Ouch.
Mu HP9826 arrived with cracks in the casing. The E-bay seller said it
happened in transit, I am not sure I believe that. But anyway, I ended up
drilling holes and putting self-tappers in to hold some of the cracks
together. It doesn't look perfect, but the machine works. Fortunately,
although the (thick and solid) plastic case was cracked, the internals --
all the PCBs, the disk drive and even the CRT -- were perfect.
It soulds like you've got a similar situation. Case damage, but good
electronics.
So basically, what I've got is a pair of feet, no screws, and the metal=20
the screws screw into is "gone". It extends further into the mainframe a=20
bit more and there is some more screwthread, but I'm trying to think of=20
a solution for the lack of metal around what is the main mounting for=20
the feet.
At this point, my two best solutions are:
- Drill the holes out a bit more (to around M5) and have a local=20
machine shop make up some threaded inserts -- M5 outside, M3.5 tapped=20
If you ask me nicely, I can possibly provide help with doing that. I have
taps and dies...
hole inside, possibly flattened on one end so they can
be easily screwed=20
in. Screw in, build up epoxy putty around the side to replace the=20
missing metal, reinstall mounting feet.
- Same thing without the threaded inserts. Drive a screw into the=20
hole, build up the putty and leave it to set (~24 hrs). Remove the=20
screw, then install the foot and reinsert the screw.
I like #1, it's more effort but likely to produce a stronger result.=20
What surprises me is that HP only used one M3.5 screw to hold each foot,=20
Are you sure it's M3.5? Have you measured it (and checked the pitch,
which IIRC is 0.6mm). On older instruments, HP used UNC screws, and 6-32
UNC (32 tpi) is similar in size to M3.5 (although not identical).
(As an aside, the oriignal jackscrews for HPIB cables were 6-32 UNC.
Later ones (and all you'll find now) are M3.5, They are not
interchangeable, but the M3.5 screw will go into the 6-32 tapped hole and
engage by pehaps half a turn).
At this point, I would kill for a drill press, a
lathe, tap-and-die set,=20
some metal rod stock and a good book on metalworking...
See above :-)
The screws are listed in the service manual as "Screw, Machine, M3.5 x=20
0.6, 25.4mm_LG (Back Feet)". Torx T15 head (if memory serves; might be=20
OK, they are M3.5, I am suprised...
T10). Naturally the closest I've got is either M3
or M4 and nobody=20
around here stocks machine screws in small quantities.
Where is 'here'?
M3.5 threads turun up in 2 main places. One that many classic computer
enthusiasts will come across, and the other in just about every house in
the UK. The former I've already mentioned (HPIB/GPIB/IEEE-488 cables).
The latter is the screws used to fix (UK) light swtiches, sockets, etc to
the backboxes.
Most electrical wholesalers, some DIY shops, and maybe even Maplin, sell
spare (or longer, etc) screws. Yes, I did once use a couple in an
emergency to hold an HPIB cable in place.
The prolem comes if you want to cut them down. An old trick is to run a
nut onto the screw before cutting it, then use it to reform the thread at
the cut end by unscrewing it. But M3.5 nuts are much harder to find than
screws. Given an M3.5" tap, it's easy to make sumething for this, but the
M3.5" tap is not in most sets (I bought them (3 taps) for making HPIB
jackposts, they are available).