Help!! 9815: Mad at the printer, 9825: Mad at the fan!


Hello Tony & al,

I apologize for asking 2 questions in one topic but maybe you can help save my household!!!

Repairing a 9815 & 9825, I've done the usual job (screw posts under PSU, gummy wheel replacement...) on both calcs.

However, before closing the lid, I've got 2 remaining problems :

- The 9815 keeps on printing the error messages and the printer is not especially quiet: I know this is by design but is it Ok if I insert an additional switch on the printer power supply wires to keep it silent when I want to ???

- The 9825 fan is producing a tremendous noise even after carefully taking into parts, greasing the axis, inspecting the fan cavity for frictions : the noise seems to come from inside the motor: does anybody know the specs of this fan for me to replace it with a new one ?? I intend to use the fans sold for today's PCs.

I surely won't disconnect the fan due to the amount of electronics warming up inside!!

Having read the maintenance manuals for both machines, I found the Hp part numbers but not the specs.

Heeeeelp, my wife doesn't want me to keep noisy calcs anywhere in our parisian flat!!!

Warm (even with the fan :-) greetings to all and thanks in advance!!!

(still married)


Warning : This is based on looking at the schematics, I have not tried any of this.

For the 9815, I see no problem in putting a switch in series with the printer solenoid (connected to the PSU/printer PCB by a 2 pin connector). What I would do is uplug that connector (thus disconnecting the solenoid) and see if the machine behaves as you want it to. If so, add the switch in series with one of the solenoid wires.

I do have to wonder about the HP design that causes a machine to print 'OUT OF PAPER' when it has no paper ;-)

For the 9825, the fan is a 120V AC (50/60Hz) unit. I see no reason why a modern replacement wouldn't work. Note that most PC fans are 12V DC, you can't put one of those directly in place of the existing fan. There is a +12V rail in the 9825 which probably could supply enough current for a modern fan, but I like to keep my machines as orignial as possible (and 120V fans are not hard to get).

I assume you've looked at said schematics...


Good evening Tony,

Thanks galore for your answer!

I'll start with the 9815 and then will go out in the cold to find a 120V fan!

Of course, I'll report back when done.

Thank you also for your 2001 explanation on the printer: 9815 printer overhaul

I received the 9815 with the printer foam spread all around the mechanism and your post did help me to restore it and also the one in my 9825!!!

Have a nice week-end!



PS : Yes I looked at the schematics on the DVD & found the 12V rail...but not the fan specs: I'll reread then...

I'll try not to consider this rail as a power supply "selfservice" to tune my machine...but I'm tempted :-)

Alea jacta est! (Oops sorry!)

Thanks again.


Edited: 29 Oct 2005, 3:17 p.m.


It is much easier to find a quiet 12V fan than a quiet 120V fan...


I guess you're right and I might go this way.

However, Tony pointed that he prefers to keep his calcs as "authentic" as possible!!

You can be sure I'll take the quietest one because I do appreciate the 9825 and try to learn HPL.

Don't shiver, if I elect to poke the 12V rail, I have a bunch of "tuning options to put in the calc such as "laser blue light" within the fan, retrolighting the keyboard :-)

I'll try to finish the 9825 before Halloween!


Edited: 30 Oct 2005, 10:28 a.m.


Put in a quiet 12V fan and use it, keep the old one handy in case you need to restore the machine to its virgin state.


I recently repaired my 9815 printer (Tony Duell's advice was, of course, invaluable! My biggest problem was finding suitable material for replacing the damper rubber foam that had turned to goo. I used thin self-sticking felt pads but they turned out too thin and not particularly impact-dampening: the printer was advancing too much and making almost as much noise as without the felt. Then I tried Dr Scholl's moleskin foam (shaved to remove the fuzzy part!!!), but it was too thick; the printer wouldn't advance. Then I found the closed-cell foam tape that came with my air conditioner, and it turned out to be just right. It's still noisier than I would like it, but it works and I'm not about to disassemble the printer for the hundredth time.

Now, I would advise against just cutting off power to the solenoid; the machine would keep printing without advancing the paper, heating up the printheads. I would assume that the design depends on the moving paper to carry off some of the heat from the printheads, exposing the heads to new, cool paper as the machine is printing. I would fear that if you don't advance the paper you may overheat the heads. I don't have documentary evidence of that, it's just a conjecture, but better sure than sorry.

I do find it annoying that the printer is used to print diagnostic messages even when the printer switch is off. Would it have been too hard to display "Error" and a number to indicate what the error was?

The fan, after a thorough clean-up, is surprisingly quiet. Maybe the ball bearings in yours are defective?

BTW, thanks to Vassilis Prevelakis for fixing the capstan of my tape drive.



Yassou John!

Thanks for your input! I'll try to find a foam-type similar to yours (air-conditionning is not that widespread in France)

I understand your point on the power cut at the solenoid but remain reluctant to put the switch directly on the printer power lines, fearing that the calc would wait some handover signal from the printer finishing it's job.

That's why, Tony's option looks attractive to me! I'll try to recheck thoroughly the schematics before I jump.

Now on the noise issue, the noisy fan is my 9825T fan which I completely dismantled and powered directly from my bench PSU : I think it's the motor. On the other hand, the 9815S fan is really quiet after cleanup and realignment!

Thanks again John!


Edited: 29 Oct 2005, 7:26 p.m.


Interesting! Inspired by your thread, I just decided to give it a try and unassembled my 9815. I cleaned the pad from the goo and tried a square-cm of window insulation tape, but it seems to be too thick - the printer doesn't advance, and yet makes a tremendous noise. Emmanuel, if you happen to find a suitable material in France, I'd be happy to receive a mail. The thickness really seems critical for the operation of the printer.



Hello Andreas!

By "Emmanuel", I suspect you mean "Etienne" :-)

Of course, I'll keep you posted as soon as I find the proper material.

However, every shop is closed till Nov 2nth and I'm really tempted to try injecting foam (mousse injectable) in the meanwhile.

I'll drop you a mail when my 9815 is definitely silent (I mean works silently!)


Edited: 30 Oct 2005, 6:38 a.m.


There is a back stop adjustment on this printer -- a screw locked by a nut on the right hand side of the front IIRC. If the new damper foam is a little too thick or too thin, you could try adjusting this. The ratchet pawl (inside the platten knob!) should pick up one tooth for each operation of the solenoid.

There is, amazingly, some useful information for this in the official 9825 service manual, including a schematic of the test rig (!).


marais wrote:

> Interesting! Inspired by your thread, I just decided to give it a
> try and unassembled my 9815. I cleaned the pad from the goo and
> tried a square-cm of window insulation tape [...]

Way too thick. Unfortunately I didn't take any pictures when we
were repairing ji's 9815S (I did the tape drive, he did the printer), but the piece of foam he inserted was very thin (about 3-4 mm).

The printer still makes quite a clatter, but it now prints OK. We wrote a short program to test the tape drive and listed it before and after saving it onto tape.

Ji promised to take a few pictures before reassembling the 9815.



Thank you, it worked on my second attempt...I use only a small strip of window isolation tape (I can bring some to Paris, Etienne!), glued to the outer third of the metal plate. I also lengthened the spring a bit, and now the mechanism works fine. I noticed that a working mechanism can be tested manually, by just pressing the plate from behind...if it clicks, it'll also work with the solenoid moving the plate.

Now for the capstan! This forum is fabulous.


Edited: 30 Oct 2005, 9:29 a.m.


Andreas, if you want, I have a capstan for you!

It's a spare left after repairing the ones in my 9815 & 9825.

If you prefer machining it yourself, I bought from my plumber the tap joints that I used to rebuild Hp-85, 98x5 and TI SR-52 capstans.

If interested, email me privately.

Cheers from Fourqueux


Edited: 30 Oct 2005, 10:13 a.m.


The fact that HP allowed the printer to print without paper (e.g. that infamous 'OUT OF PAPER' error) means that it can't be that damaging to the head. As a counterexample, the 7245 printer/plotter (there's one on my bench at the moment..) has a fairly complex out-of-paper circuit, and even detects if the sensor has failed. So presumably something nasty happens to that machine if it's run without paper.

I also don't believe that the platten roller carries that much heat away in the 9815. It's not a metal roller, after all.

Now, I wouldn't disable the solenoid and the out-of-paper sensor and, say, try printing a program listing on the 9815. That might well do damage. But disconnecting the solenoid would leave the out-of-paper sensor working, so what would happen if it tries to print (assuming there's no paper in the machine) would be to print OUT OF PAPER and then stop. I don't think that would do damage.

If you want to leave paper in the machine and shut it down, you might look into forcing an out-of-paper error, e.g. by also disconnecting the LED of the sensor.


Hi John,

RE: heat build up if pplatten stalls: yes thats how it works.

Hey Man, I like your PIC code!


Possibly Related Threads...
Thread Author Replies Views Last Post
  9815 data cartridge drive (also 9825 / 9845 / 85 / 87, and who knows what else) John Ioannidis 2 456 06-12-2013, 07:20 PM
Last Post: Craig Ruff
  9815 Service Module John Ioannidis 0 299 06-10-2013, 02:56 PM
Last Post: John Ioannidis
  Printing HP 9825 data Norman Pillsbury 3 514 06-01-2013, 10:08 PM
Last Post: David Ramsey
  98228A 9885/9895 ROM for 9825? Craig Ruff 4 487 05-15-2013, 07:18 PM
Last Post: Craig Ruff
  NEW!!! HP Calc FAN Page On Facebook!!! Kristine 5 525 11-18-2011, 07:51 PM
Last Post: Calum Tait
  HP-9825 Paolo Cipollone 2 328 09-13-2011, 02:13 AM
Last Post: Paolo Cipollone
  9815 Keyboard Disassembly aj04062 3 437 08-16-2011, 12:25 PM
Last Post: aj04062
  Board Stacking Connector HP-9815 aj04062 2 386 07-15-2011, 10:06 PM
Last Post: aj04062
  Help! HP-19C printer gone mad - fixed :-) Philippe Lasnier 1 285 04-25-2011, 10:08 PM
Last Post: Katie Wasserman
  Help! HP-19C printer gone mad Philippe Lasnier 12 916 03-12-2011, 12:08 PM
Last Post: Philippe Lasnier

Forum Jump: