12 Sep
2010
12 Sep
'10
7:31 p.m.
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.
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
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
together?
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?
This would be icing on the cake, since it would be shame to let such a nice
machine go unused. However, I do have the Prologix GPIB interface with
PyVISA/Scipy/Numpy,
Thanks for any input,
Dave
13 Sep
13 Sep
8:22 a.m.
-----Oorspronkelijk bericht-----
Van: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org]
Namens Dave
Verzonden: maandag 13 september 2010 4:32
Aan: cctech at classiccmp.org
Onderwerp: HP 9825 refurbishing
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.
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 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
together?
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?
This would be icing on the cake, since it would be shame to let such a nice
machine go unused. However, I do have the Prologix GPIB interface with
PyVISA/Scipy/Numpy,
Thanks for any input,
Dave
Dave,
If you want to use the HPDrive util, you need the 9895A ROM and the IO ROM.
The 9895A ROM is hard to find the IO-rom isn't with those rom's you can use
HPDrive on a PC with a HP-IB card as Mass Storage Unit.
Tape drives are easy to refurbish but most of the HP-tapes are bad they
losing the magnetic layer.
It's possible to convert the drives so they can use QIC40 tapes, I do have a
short description and drawing of this mod.
You can order new DC100A tapes by Athana at ~ $38,- a piece.
It's also advisable to add a crowbar circuit to the psu the 723 regulator
IC's and power transistors don't life forever. When they go you will be
grateful for adding the crowbar circuitry.
-Rik
10:23 a.m.
Hi Rik,
Thanks for the info. I would be grateful for your tape conversion description,
since I would like to restore the machine fully. At $38/tape, I doubt I'll be
using the tape drive much :-( Until I come up with another storage method, a
tape will have to do.
Looking at the PSU, I have rev. E. It looks like a crowbar could be useful
after the 5V switcher, and the 12V linear reg. I would think it couldn't hurt
to replace the pass elements of the 5V reg and the 12V reg (Q3 and Q4). Did you
find that the 723 regs failed, or the pass elements? The electrolytics are
looking aged, so I'll replace them preemptively. I would be very interested in
any diagrams and/or photos of your PSU mods.
Best regards,
Dave,
If you want to use the HPDrive util, you need the 9895A ROM and the IO ROM.
The 9895A ROM is hard to find the IO-rom isn't with those rom's you can use
HPDrive on a PC with a HP-IB card as Mass Storage Unit.
Tape drives are easy to refurbish but most of the HP-tapes are bad they
losing the magnetic layer.
It's possible to convert the drives so they can use QIC40 tapes, I do have a
short description and drawing of this mod.
You can order new DC100A tapes by Athana at ~ $38,- a piece.
It's also advisable to add a crowbar circuit to the psu the 723 regulator
IC's and power transistors don't life forever. When they go you will be
grateful for adding the crowbar circuitry.
-Rik
2:35 p.m.
If you want to use the HPDrive util, you need the
9895A ROM and the IO ROM.
The 9895A ROM is hard to find the IO-rom isn't with those rom's you can use
HPDrive on a PC with a HP-IB card as Mass Storage Unit.
I thought hte HP9825T had most of the ROMs built-in. IIRC, the only ones
that are misisng are the disk ROMs anmd the Matirx ROM (those have to be
added as front-port modules). If this is the machine I am thinking of,
the IO ROM is built in.
Tape drives are easy to refurbish but most of the
HP-tapes are bad they
losing the magnetic layer.
It's possible to convert the drives so they can use QIC40 tapes, I do have a
short description and drawing of this mod.
If this is the Athena mod, it's slightly curious, in that it involves
paralleling resistotrs when it's easier to desolder the original
write-current control resistor and replace it by one of the correct value.
You can order new DC100A tapes by Athana at ~ $38,- a
piece.
It's also advisable to add a crowbar circuit to the psu the 723 regulator
IC's and power transistors don't life forever. When they go you will be
grateful for adding the crowbar circuitry.
Seconded!
-tony
3:28 p.m.
I thought hte HP9825T had most of the ROMs built-in.
IIRC, the only ones
that are misisng are the disk ROMs anmd the Matirx ROM (those have to be
added as front-port modules). If this is the machine I am thinking of,
the IO ROM is built in.
That's right. The Extended I/O ROM is built in. Under the cover, the following
are listed:
9872A plotter, Genereal I/O, Extended I/O, Adv. Programming, String, Sytem
Programming
From the hp9825.com site, I gather that it should be
possible to transfer
programs to and from the 9825 in ASCII format via the serial
card and some Sytem
Programming ROM routine. Not exactly the same as mass storage, but better than
nothing.
> It's also advisable to add a crowbar circuit
to the psu the 723 regulator
> IC's and power transistors don't life forever. When they go you will be
> grateful for adding the crowbar circuitry.
Seconded!
I plan to do this. Any pointers from those who have done the mod?
-tony
14 Sep
14 Sep
1:03 p.m.
That's right. The Extended I/O ROM is built in.
Under the cover, the following
are listed:
9872A plotter, Genereal I/O, Extended I/O, Adv. Programming, String, Sytem
Programming
I can never rememebr all the suffix letters for the 9825 series :-). But
from what I remember, the earlier/simpler machines ahve
the HPL firmware
in a modle that slots into the RHS of the machine. The memroy
boards in
the 'stack' are just RAM, either 4K or 8K words. All extension ROms have
to be added by front port modules.
Later machines have a ROM/RAM board on top of the 'stack' It contains the
HPL firmware and most of the extnsrtion ROMs. IIRC there's a DIP switch
to select between the 9862 and 9872 plotter ROMs. The RHS module is not
used, there's a cover clipped over the hole, and a couple of track cuts
on the processor board to disable it (these cuts my be hiddeb my the CPU
hybrid.
The top model (IMHO) has thatr with another special 16K word RAM board under
the ROM/RAM board. With that one you get soemthing like 31K words of RAM
_and_ almost all the ROMs.
From the hp9825.com site, I gather that it should
be possible to transfer
programs to and from the 9825 in ASCII format via the
serial card and
some Sytem
Programming ROM routine. Not exactly the same as mass storage, but
better than nothing. > It's also advisable to add a crowbar
circuit to the psu the 723 regulator
> IC's and power transistors don't life forever. When they go you will be
> grateful for adding the crowbar circuitry.
Seconded!
I plan to do this. Any pointers from those who have done the mod?
3:48 p.m.
> It's
also advisable to add a crowbar circuit to the psu the 723 regulator
> IC's and power transistors don't life forever. When they go you will be
> grateful for adding the crowbar circuitry.
Seconded!
I plan to do this. Any pointers from those who have done the mod?
15 Sep
15 Sep
7:36 a.m.
Dave,
At http://www.hpmuseum.net/display_item.php?hw=171 at the documentation
section you find the diagrams made by Tony.
For the crowbar I use a zener SCR/Thyristor construction, I didn't made one
for the negative voltages.
But I have had one memory board destroyed due to a missing neg. voltage, I
had to replace almost all the memory chips.
If you search the archive you'll find the posts about it.
I do have some spares if you need something let me know.
-Rik
9:15 a.m.
At http://www.hpmuseum.net/display_item.php?hw=171 at the documentation
section you find the diagrams made by Tony.
For the crowbar I use a zener SCR/Thyristor construction, I didn't made one
for the negative voltages.
-Rik
Wow, amazing. Those schematics are quite a piece of work, Tony! Did you
service these machines professionally, or was that a labor of love, or both?
I had seen the site, but didn't notice the buttons for documentation at the
bottom! By the way, thanks to Rik and Tony for your very helpful pointers and
responses.
With this info, I should be able to rig up a ROM cartrige, in case I'm able to
get my hands on images of the Matrix, Disk, and Network Analyzer control images.
Best regards,
Dave
12:41 p.m.
Wow, amazing. Those schematics are quite a piece of
work, Tony! Did you
If you poke arouind that site some more, you'll dins that the 9825 is not
the only machine I've pulled apart... I think somebody claimed there's
over 100 'HPxx_SchematicsByTonyDuell' files on that site.
service these machines professionally, or was that a
labor of love, or both?
I have never serivced any machines professionally.. I traced out the
schematics intitially to maitai~n my own machines (I like the engineering
qulaitiy of _old_ HP hardwareand then decided to share them. In a couple
of cases I produced schematics that I didn't need at the time, just for
interest...
I was aseisted by another HPCC memeber who scans my diagrams (I don't
have a scanner, or anything modern like that). You can buy a DVD-ROM of
them from HPCC, the profits go to the club, BTW, not to me.
I had seen the site, but didn't notice the buttons for documentation at the
bottom! By the way, thanks to Rik and Tony for your very helpful pointers and
responses.
Poke around that site. There's a lot of interesting stuff there, on all
sorts of HP machines nad peripherals. Be warned you will spend houes
looking at the manuals, and an equal time trying to find some of the
items on E-bay...
With this info, I should be able to rig up a ROM cartrige, in case I'm able to
get my hands on images of the Matrix, Disk, and Network Analyzer control images.
Good luck. And feel free to ask if there's anything you want to know...
-tony
4:48 p.m.
If you poke arouind that site some more, you'll dins that the 9825 is not
the only machine I've pulled apart... I think somebody claimed there's
over 100 'HPxx_SchematicsByTonyDuell' files on that site.
. . .
Good luck. And feel free to ask if there's anything you want to know...
-tony
Wow, no kidding! I found several instances of your efforts already. Great
stuff!!
I also have already alloted WAY too much time on that site today. . .
Dave
12:05 p.m.
>
It's also advisable to add a crowbar circuit to the psu the 723 regulator
> IC's and power transistors don't life forever. When they go you will be
> grateful for adding the crowbar circuitry.
Seconded!
I plan to do this. Any pointers from those who have done the mod? There's not much space in there, and I hate to cut
traces and have fat wires all
over the place. I'm thinking the best options to add the crowbar circuits would
be:
Remember the crowbar goes in parallel with things (you need to pick up
the votage rails to sense them, and have an SCR which shorts a suitable
point (either hte rail or the input to the PSU) to ground. So there
shouldn't be any need to cut traces. I wonder if there's enough space to
build this as a pgyback to the PSU regulator PCB...
Also, it's good to know which outputs really need
the crowbar. For example,
-12V is regulated to -5V with a Zener, but is also separately regulated on each
RAM board, so is it important to protect the -5V? What's using it?
I will have to shcem schematics. It wouldn't suprise me if it wa used by
the procesosr hybrid module or soemthing like that.
Finally, some of the circuits are fused (+12/+7V), so
it may be enough to place
tack a hefty Zener across the output in some cases to blow the fuse.
I think I would add the normal SCR crowbar.
By the way, does anyone have full schematics for this machine? I am going off
Yes.
There's a lot of information available from http://www.hpmuseum.net/ This
is the Australian HP Museum site, and is somewhat hard to find your way
around at first. I normally follow the 'documentation' link from the
homeapge and look down the list (since not all manuals are listed under
all the machines they apply to -- an obvious example is that since the
HP9831 hardware is almost indentical to that of the HP9825, you would
need ot look at the latter if you want manuals on the former...)
Don;'t try this site on a dial-up connection :-). There's a lot of
interesting stuff there, and if you're like me you'll read all sorts of
related manuals for intereast...
Anyway, I beleive you can get some HP blueprints from there which apply
to the early versions of the 9825. You can also get 'my' schematics for
the machine (all versions that I've seen) if you can stick my handwriting.
the service manual scan from the HP calculator museum
(Great work, David
The service manuals is a boardswapper guide (and is available for free
from the site I mentioned). It dors contain some useful
information
though. One thing that is there (IIRC), is the schemeatic for the
printer test board. I really must make one sometime...
Hicks!). It would be nice to get the interfacing info
for the ROM modules and
the I/O ports.
In general the I/O module manuals contain schematics... The I/O bus is
not hard to figure out from that.
The ROM modules have internal address latches and address decoders. So
far I've seen 3 types. One uses a pair of HP custom ROM chips (16 bits
wide, with intenral latches and decoders). Another uses more conventional
ROM chips and standard glue logic. And the last is bank-switched, with
the bank control logic being standard TTL parts .Schematics for the first
2 are in the HP9825 diagram set I mentioend, I don't think the last one
(I came across it in the later disk drive ROM) is up there yet, but if
you need it, I can tell you (off-list) who to contact.
-tony
13 Sep
13 Sep
2:28 p.m.
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
semi-joking here)
I assume yo've found http://www.hpmusuem.net/ where you can get manuals,
etc, from.
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
together?
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
tried them.
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?
-tony
5212
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days old
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