HP Integral PC Manuals?

Tony Duell ard at p850ug1.demon.co.uk
Fri May 2 17:52:19 CDT 2008


> Yeah, I took it apart, cleaned out the old grease and applied a tiny 
> amount of light oil on various joints.  It seems to be working fine so 
> far.  That's about as far as I've the machine apart thus far.  I need to 
> give the printer a going-over and find some ink for it, haven't looked 
> into that yet.


The printer is a normal thinkjet. Well, normal-ish Thinkjet. It uses the 
same 'printhead' (ink catridge), etc. I ahve no idea where you'd get one 
from now, though (but would like to know :-))

The main difference between the Integral and a normal Thinkjet is the 
relative positions of the mechanism and control PCB. The control 
circutiry is on the Logic B PCB, which is on the front side of the main 
chassis plate, behind the display. The PCB you see when you take the back 
cover and rear screen plate off is Logic A, that's parallel to Logic B on 
the other side of the chassis plate.

Anyway, the circuitry is standard (it's the HPIL version of the 
microcontroller, but arranged for a mains PSU (oviously), but the 
different layout means that the cables between the mechanism and the PCB 
connectors are longer in the Integral than in a noraml Thinkjet. This is 
a minor prolem with the motors (the wires are integral to the motor, but 
if you had to replace either motor with one from a normal Thinkjet, you 
could cut the wires fromt he old motor at a suitable point, cut the 
connector off the repalcement motor, and solder/heatshrink the 
connections. Anyway, motors rarely fail.

The problem is the flexile PCB that links the carriage to the PC, and 
whihc carriws the printhead signals. It's longer than a normal one too, 
and those _do_ fail, particualrly if th ink cartridge leaks onto it (at 
the front of the carriage), and it's left in that state. Replaceing it is 
not too hard if you can get the part, but kludging in a normal-length 
flexiprint could be 'interesting'.

If you want to get the printer mechansim out, you have to remove the 
logic PCB chassis first. As part of that you unplug all the cables from 
the Logic B PCB, including all the Thinkjet mechanism ones. You don't 
need to remove the PSU/backplane box. With the logic assembly out of the 
way, you remvoe the RH (lookin from the front) spaceer at the top to free 
the grounding tail on the Pritner control panel (if you don't do that, 
you _will_ tear said tail), then unto the obvious screw and take the 
control panel out. THe PCB is the stnadard Thinkjet one, the wires are, 
again, longer. Then I think it's 3 screws that hold the mechanims in 
place, with those out it just lifts out.

The mechanism is overhauled like a normal Thinkjet one. I don't know if 
the Thinkjet service mnaula is on the web anywhere, I have it on paper 
(but as ever, no scanner). If you want to tkae it apart, I can talk you 
through it. Much of it is biouv (but there are some tiny dowel pins that 
drom out and get lost if you're not expecting them). You need a good set 
of Torx driers.

Basically, I do it in the following order (I think).

At the back, take off the carriage motor, home sensor and paper-out 
switch and actuator (the latter has a magnet that operaates the reed switch).

Take off the cleaning pad holder

Take off the cover on the RHS, then the platten motor

Take off the paper bail (E-circlips at each end, there are dowel pins 
here that fall out). Take the rollers off that. If necessary, remove the 
torsion springs and the bail support arms

Take off the platten gear, then the E-circlik at the other end and the 2 
bearings. Lfit out the platten and take the parts off the shaft -- when 
reassembling, you have to line up the sproket teeth, of course. Then take 
out the paper guide 'basket'.

To remove the cariage, first undo the screw holdign the drive cable to 
it. There's a plastic washer on the screw to hold the cable in place -- 
make sure that's fitted and thusthe cable is not going to unwind. Then 
free the flexiprint from where it's lightly glued to the chassis, take 
out the carriage rails (E-circlips) and lift out the carriage

The carriagel comes apart (although HP don't recomend it). The bottom 
secion can be freed by frobing the locking part and sliding it free. Then 
there are 2 little plastic clips that hold the flexiprint to the front 
part of the carriage, with those removed you can fold the flexiprint and 
feed the end throug the carriage slot. 

IO have never tired to remove or replaec the carriage drive wire and 
gearbox. HP claim that's not field-repairable. I suspect special clamps, 
etc are going to be very useful, one day I will give it a go (I have at 
least one THinkjet with a wrecked flexiprint that I'll experiment on). 
It's worth remembering if you do this that if you refit the carriage 
motor, you can lock the motor, and thuse the mechanism connected to it, 
but passing a suitable current trhough one of the windings. That would 
prevent the pulley from turning, for example.

[...]

> Cool, I'll keep those instructions  around for reference in case I need 
> to take it all the way apart (or start feeling adventurous).  My 
> Integral is very clean (even came with the "dummy" shipping floppy in 
> the drive when I got it) so I didn't feel the need to take it all the 
> way apart to clean.

I guess I'm justa curious hardware type, I like to see what goes on 
inside all my classic computers :-)
> I have both a 512k expansion and the RS-232 card installed in mine, I'll 
> have to look  up your article and see about upgrading the 512k card to 1M...

The RS232 card has an interesting undocumented feature that AFAIK no 
software supports (but I would like to be proved wrong). It's acutally a 
_dual_ RS232 port.

The 68681 chip used on said PCB is actually a 2-channel device. The 
second channel is uffered to RS232 levales and wired to the seocndary 
('back') channel pins on the DB25 conenctor. I think things like SRTS are 
wired up too. 

> Agreed.  It also would have been nice if they'd put a bit more in the 
> system ROM.  As it is, there's absolutely no software or tools aside 

Well, a hard disk would have got round that problem :-).

-tony




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