HP9830 keyboard

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Mon Mar 17 18:36:18 2003

I am currently restoring an HP9830. I guess this is a classic computer
(for all it says 'calcualtor' on the nameplate) because it runs BASIC,
and is 30 years old!

Repairing the electronic faults has not been a problem (boards of TTL --
yum...). It now powers up, runs programs, drives the 9866 printer sitting
on top of it, saves/loads to cassette, and so on.

I am now left with the keyboard which has 5 problems :

1) The 'Stop' keycap is missing, although the switch is complete and
undamaged

2) The keycaps need cleaning

3) The power-on lamp on the front of the machine is burnt-out

4) The mains switch is broken

5) The plastic keyboard bezel (surround) was badly broken by the postal
'service'. I have most of the broken bits of plastic

OK, solutions ...

1) My junk box supplied a keycap that will fit (without modifications),
although it's too short and has the wrong label. It'll do for the moment
until I cna find soemthing better (unless anyone here is mad enough to
have stripped a 9830 for parts -- I hope not!)

2) Trivial to put right!

3) This is a wire-ended bulb, running off the 5V line through a 22 ohm
resistor. I can get a 5V 60mA bulb -- as I don't want it to be
particularly bright this should be fine. Does anyone know what the
original bulb was, though.

4) This is more of a problem. The original switch is a DPDT rocker (and
all 6 terminals are used -- the NC contacts connect to a 1M resistor used
to discharge the mains filter when the machine is turned off). It mount
with 2 screws onto the keyboard chassis. There is very little space in
that area too. I don't want to modify the machine more than I have to,
and I can't find a suitable switch in any of the catalogues. HP used the
same switch on many devices in the 1970s -- the 9866 printer has an
identical switch, so do the I/O expander and disk drives for my 9825.
Anybody know of a source (I can provide more details, like dimensions,
etc, if anyone thinks they can help)?. If all else fails, I'll replace
the switch on one of my 9885 drives (where there's a lot more room) and
use the switch removed from that drive in the 9830.

5) Any suggestions as to how to repair this? The plastic will stick with
dichloromethane, but of course it's not very strong. I have heard of a
technique of soaking a piece of cloth in said solvent and sticking it to
the back of the plastic to strengthen it. Anyone ever tried this and have
any tips?

-tony
Received on Mon Mar 17 2003 - 18:36:18 GMT