HP 2225A Thinkjet Printer not printing



I have a non-printing HP 2225A Thinkjet Printer I am trying to fix, but sofar not succeeded. Seems to be working but puts nu ink on the paper.
1) The printhead is moving normally, also at start-up when you can have him print one page with all kind of test text.
2) I measured the print head resistors. I am not sure abou which contacts but between certain point I measure 120 ohhms. I checked this also at the connector at the main circuit board. There I head the same resistance. When removing the printhead then measured at the connector the resistance goes to infinity, so it seems to be oké.
3) The red powerlight always burns. I checked the battery under load in the printer, stays around 8 volts which seems reasonable given the fact that the accu is 6 cells.

For that I think it is something in the powersupply part in the printer.

Unfortunately I do not have the scematics of the printer.

Any suggestions where and how to proceed ?

Thank you.



You didn;t mention if the print head was old or not. The print head and ink cartrdge are the same piece on the Thinkjets, of course. New cartridges are still available for those machines. The current HP part number is 51604A. I found some at a local Office Mart. They weren't on the shelf, but they showed up in inventory on the computer. It took me an hour to get the clerk to bump my complaint up to a manager. He said "no" right away too, but I pressed him on why he had them on the system. Eventually, he brought them out from a back room with an apology.


Hi Howard,

Yes, it is an old printhead. It was in the printer when I bought it last year. The ink itself is however still fluid and looks almost full. I remember from the past that when it get's empty the rubber bag get's a "dimple"if I express myself in English.

So far I was not able to locate a spare in the Netherlands. I will give the customer service at HP a call tomorrow to see if they are able to get me a new one.



You can purchase them online from Carrot Ink :


I hope this helps...

rgds, Wilson


Hi Wilson,

Thank you for Carrot ink.
I just gave it a check. Due to the fact that I am not a US resident payment is very difficult (money order required, no foreign credit cards) and shipping to Europe is 33 dollars. This is unfortunately then a very expensive printhead (the cartridge itself is 13$). I will continue to search to find some Europe located suppliers.



Hi Gents! i´m following your conversation with great interest.
I also bought an 2225B (HP-IL) Printer for my 41-collection at ebay from the U.S..
It isn´t working either.
Yet i bought a new cartridge in Germany with expiry date May 2007!
The adress is :

Danziger Platz 19
D 71332 Waiblingen


It was 13.57 Euro´s + 4.10 p&p

The Thinkjet also looks pretty working mechanically but wasn´t printing a dot. Since this morning it refused mfrom power-up also. despite the battery looks fine. That´s why i´m also interested in schematics and any repair hints.
BTW there is a printer repair page on the web. Just google "Thinkjet" and "repair". It gives some hints, but nothing that was not mentioned yet.


Most of the time when a Thinkjet doesn't print, but the carriage and paper move correctly, it's the flexiprint cable, as discussed here over the last few days....

I have the service manual (with schematics). As ever I am happy to look things up for people who are repairing HP calculators/peripherals. But as mentioned in another thread I have no scanner, so I can't e-mail bits of the manual.


have you tried to see if ink can come out of the printhead?

the manual suggests using a paperclip to push the bladder until a drop of ink appears on the printhead.

Wipe the printhead with a soft cloth and try the test again.

I may also be that the connections to the printhead are coated with leaked ink (unfortunately the 2225A and cartridge were designed to be in continous use and leak when left idle).

BE VERY CAREFULL WHEN CLEANING THE BASE OF THE CARTRIDGE (the black plastic holder that is visible when the print cartridge is removed). you can easily damage the contacts and then the entire assembly will have to be replaced (the contacts are bonded on the flexible PCB that runs to main PCB and I do not believe these can be repaired.

I would suggest removing the base and holding it under running water without any mechanical assistance (Q-tips, etc).




I tried pushing into the hole at the back of the printer head. I think I will be with black fingers for the rest of the week unfortunately, so the answer to that is yes.
I will gently clean the base unit later tonight. I took a daring approach today and disassembled the complete printer and hooked my scoop to the print head connection on the circuit board. When i started the self test function I saw a lot of pulsing on the scope. For that reason I am continuing on the assumption that the electronics are oké. I also managed to find a Europe based supplier for new print heads so I ordered a new head. It will take about two weeks to arrive at my place. So except for cleaning again the base of the head I think I should wait now for the new print head and keep my fingers crossed it will work. If not back to disassembling again and maybe removing the whole print head to do a more thorough analysis, but to be honest it scares me a bit. I am not 100% convinced at this moment I will be able to get it in one piece again, but that is a worry for 2 weeks from now.



If you aren't doing all this work for the love of it, remember that these printers come up on ebay fairly frequently. Even if you have to pay shipping from the US, the price might be cheap compared to the labor.


hi if you need more informations about available cardrige to 2225
i found them with paper in germany still now

if you are believing that the head is out let you send 1 or 2 from the dealer in germany but d ont forget only average 500 perhaps
less sheets printed.....
let menow if you are interested

i have hp 110 + 9114 + 2225.....



Hi Gaston,

I ordered a set of heads yesterday already with a company called microfix in the Netherlands. If this does not work out, I will come back to you for sure.

Thank you for thinking along.



Firstly, I have the Thinkjet _service_ manual with full schematics. If you contact me at the above (unmunged) e-mail address I can look stuff up for you. This manual is not alongside me at the moment, so I am working from memory.

One thing confuses me. You mention that the battery is fully charged, but the Subject line refers to the 2225A which IIRC is the mains-powered HPIB model. There are significant internal differences mostly due to the different PSU (which leads to the motors being different!). What are you working on?

I think you've done the first test. The flexiprint cable to the PCB is the printhead connector. One of the tracks -- I think it's the middle one -- is obviously different to the others, it's the common connection. The others are the drives. With the cable disconnected from the PCB, check for resistance between the common connection and each of the others in turn. If any are open, suspect the printhead or the flexiprint. Be warned that ink leaking from the cartridge often corrodes the flexiprint at the carriage end, and AFAIK the flexiprint can't be repaired. I have dismantled a carriage to replace it, but getting the part is presumably next-to-impossible now.

The printhead drivers are ULN2803-like things (maybe 2003's). They take 12 outputs (IIRC) from the processor chip (the big one, the other 2 large ICs are the font ROM and RAM, they communicate with the processor by something that's remarkably close to Saturn bus :-)).

In the battery-opperated Thinkjet (2225B and 2225P IIRC) there's a little switching converter to step the battery voltage up to drive the printhead. I think you should be able to measure something in excess of the battery voltage at the common connection to the printhead when the thing is printing. I can see if the manual gives a voltage for this point.


Hi Tony,

I thought it was the 2225A, but for it has an HP-IL interface it is probably a 2225B. On the printer (and carton box) it only indicates Thinkjet.

I will take it apart this weekend to measure the resistance between the center trace on the flexiprint and the other traces. The connectionpoints for the printhead were literally soaked in Ink which I cleaned more or less with some paper, assuming this was enough. I will revisit this when taken apart given your remark that the ink can be corrosive..

I think the switching converter is oké for the red light on the button circuit board is burning bright red continuously. Also when switching on and keepting two buttons pressed the printhead is swiftley moving formm left to right and the paper is advancing. The only thing lacking is the ink printed on the paper.
If you have a few testpoint with the associated voltages I will make a check to that.

I will get back this weekend with the results after having it disaasembled.

Thank you



I will have to check the schematics, but there are at least 2 power supply rails in this printer. A 5V line for the logic, and the stepped-up voltage for the printhead. I can't remember how the motors are powered, possibly straight off the battery.

IIRC (again) the printhead supply is only turned on when it's actually printing, to save the battery. The red LED does not depend on the printhead supply working.

A ruined flexiprint (due to ink corrosion) is a common cause of no printing in these printers. I can tell you how to replace it if you can get the part. It's the same part in all Thinkjets apart from the one built into the Integral PC, that one is longer.


I looked in the service manual last night, and I was basically correct.

The motors run off the unregulated 'Vbatt' line. This is regulated down for the logic. There's a step-up SMPSU for the printhead

That SMPSU provides around 22V to the printhead common line when the machine is printing. It's based round a 555 timer (wired as an astable) driving a power transistor. There's a voltage comparator between a divided-down version of the 22V output and a 1.2-ishV reference voltage. That comparator feeds the reset pin of the 555 to stop the oscillator when the output gets too high.

There's a 2-transsitor circuit to remove power from the 555 unless the machine is actually printing (this is to save the battery, of course).

So what I'd do next is find some way of connecting a voltmeter to the printhead common connection when the machine is running the selftest or similar, and see if that 22V is present.


Hi Tony,

I look already forward to the weekend to have hours going in again with voltmeters etc.



Hi Tony,

Opened the 2225B again and went down deep until I had the flex connector out.
3 of the contacts were defective, which is really bad. It bad spot was between the flex cable itself and the contact point were the ink head is making contact. The worst of all places.
I experimented at a corner to see if the base was heat resistant enough to solder one tiny wire over the gap, but even when coming close to the cable, it already started to melt.

I am afraid this printer therefore one has seen his Waterloo, unless I manage to get a spare flex cable somewhere. This is bad for it complete to the carton box, foam, everything and also still white, no yellowing at all.
As a last rescue I will put an add to that matter in this website, but I have no great hopes to getting a spare part.

Thank you for your guidance,



Unfortunately a defective flexiprint cable is a very common cause of no printing on these machines, and the point where it fails is where you're having problems, at the cartridge contacts.

The good news is that it's the same part on _all_ Thinkjets (well, as I said earlier, apart from the one built into the Integral). If you can find another Thinkjet with other faults, or damaged case, or something, you can swap the part over.

Let me know if you find one, and I'll tell you what to undo. It's not totally obvious, you don't want to release the cable that moves the carriage. Re-threading that is 'fun'...

And for other Thinkjet (and Integral) owners here, please don't leave the cartridge in the printer if you're not using it. Leaking ink is the main cause of flexiprint damage


Hi Tony,

Thank you, keep my finger crossed to another failed Thinkyet.
I took of the carriage by loosening the screw and then winding some solder wire in a 8 like figure around the screw, so the transport wires could not get away from the screw.


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