HP 9825 refurbishing
ard at p850ug1.demon.co.uk
Mon Sep 13 16:28:29 CDT 2010
> Hello all,
> I bought one of the HP 9825's that Marvin recently posted here about (via VCM
> auction). It's a 9825T and seems to work perfectly, along with an HPIB
> interface I bought off Ebay. Of course the case needs cleaning and there is a
> penny-sized chip from the corner of the bezel, so I've got the whole thing
> disassembled, and am now in the process of rebuilding the chipped bezel corner
> with JB-weld. Next step is to repaint the case, then replace the at-risk PSU
> caps, refurbish the tape drive, clean the keyboard, etc. The unit is
> beautifully engineered, by the way.
Of course it's beautifully enginered. It's an old HP :-) (only
I assume yo've found http://www.hpmusuem.net/ where you can get manuals,
I don;t know which keyboard you have, but if it's the older 'chicklet'
one, be caeful when dismantling it. You will end up with keys all over
the floor if you remove al lthe tiny screws and then pull the PCB off.
Don't ask how I found that out.
> Some questions for the group:
> 1) Does anyone have a suggestion for the best paint to match the original
> color? If I can find a close match, I'll just tape over the legends on the
> bezel, and paint around them. If I can't get a good match, I still may do the
> same thing, or I'll just paint the whole thing, and then print out some decals
> on a color printer to match the original legends. Or, if anyone here has a
I dont hjave the equipment to do this, but I suspect everyone else does....
The vintage radio resotres often scan the tuning dials, etc of old sets
clean them up on the PC, and then print out a replacement. If oyu have a
colour scanner and printer, perhaps you could scan the legents and print
out the replacements in the right size, colour, etc.
> better suggestion, I'd love to hear. Any suggestion for type of paint? I found
> a can of Rustoleum brand almond-color satin finish enamel spray-paint. Is that
> a good choice, other than wrong color? I also just bought an HP 87 on Ebay as
> well, so I'm hoping that whatever I learn here, I can apply to refurbishing the
> 87 as well.
> 2) While the unit is completely disassembled, are there any hacks, mods,
> upgrades, etc. that I may want to know about before I put everything back
You know do the tape drive (rollers, and check the 2 little filament
lamps in it, one for the EOT sensor, the otehr for the tacho). Check the
printer mechanism too, there's a rubber bumper that often fails, It's not
hard to replace. I can give the procedure for taking the printer apart if
it's not obvius/in the manual
For some totally inexplicable reason HP did not fit crowbars to the PSU
in the 9815 or 9825. If you are going to use the machine, I would
certainly put crowbars on the +5V and +7.5V outputs, and probably on the
otehr outputs too. The 7.5 rail is the one most people miss, but it's
used by many of the custom chips, so you don;t want an overvoltage there...
> 3) I would like to use this in my home lab, so I was hoping to find a way to
> store programs without using the tape drive or a disc drive. Is anyone there
> moving data between the 9825 and a PC? Can some of the utilities on hp9845.net
> be used to interface with the 9825 as well?
The plain 9825 will only store programs on a tpae drive. There were 2
disk ROM modules that plug into the front of the machine -- these ROMs
are not buil into any 9825. The older module worked with the 9885 8"
drive only, this has a suctom 16 bit parallel interface which seems to be
undocumetned (an project to tackle sometime, there is some information in
the Pascal system documentation for the 9000/200 machines on bitsavers).
The later ROM would also work with the 9895 drive, which is an HPIB
device using the Amigo protocol I asusme that this can be used with some
of the untilities on hp9845.org, but not having a machine to run them on
(and having an objection on principle to binary-only software), I've not
A silly thought. I beleive you have the Sysmte Programming ROM built into
your machine. That has a keyword (STORE iirc) that stores a string as a
line in program memeory. Could you write a bootloarder (stored at high
line numbers) to read strings in from a PC (say over a serial interace)
and store them as a program?
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