Hacking an Inkjet Printer

[MMS]

I have an old inkjet printer and was taking it apart (an old Lexmark).
I looked at the back, and there looks like there is a matrix of copper
connections back there. Just tinkering, I took a 9V batter with two
wires, and tried touching a few of these pads to see if I could get it
to fire....some sputtering, but not much.


Does anyone know about inkjet printers and cartridges? Is there a good
website that might help me out (I am googling this idea as well)? I
would love to be able to figure out how to make the cartridge fire with
some simple electronics (its part of a much bigger curiosity I have
festering in my mind)...thanks!


-M-

 

[Tom]

I have an old inkjet printer and was taking it apart (an old Lexmark).
I looked at the back, and there looks like there is a matrix of copper
connections back there. Just tinkering, I took a 9V batter with two
wires, and tried touching a few of these pads to see if I could get it
to fire....some sputtering, but not much.

It probably runs on 5V logic and 12V drive for motors so the 9V will
probably not be enough to drive a motor but will be plenty to fry the logic.
I would try to find a ground and then get a scope on the pins while the
printer is knocking out a test page.

 

[[email protected]]

I have an old inkjet printer and was taking it apart (an old Lexmark).
I looked at the back, and there looks like there is a matrix of copper
connections back there. Just tinkering, I took a 9V batter with two
wires, and tried touching a few of these pads to see if I could get it
to fire....some sputtering, but not much.

Does anyone know about inkjet printers and cartridges? Is there a good
website that might help me out (I am googling this idea as well)? I
would love to be able to figure out how to make the cartridge fire with
some simple electronics (its part of a much bigger curiosity I have
festering in my mind)...thanks!

Asfair, they have technology to explicitly block such attempts. To defeat
"pirate" ink (you know the black kind . So if you want this either
reverseengineer it (logic probe) or fix an old matrix printer without that
crap. Maybe some other manufactor are more consumer friendly.

 

[Michael Black]

It probably runs on 5V logic and 12V drive for motors so the 9V will
probably not be enough to drive a motor but will be plenty to fry the logic.
I would try to find a ground and then get a scope on the pins while the
printer is knocking out a test page.

I needed a 24v supply to power an old powerbook, and for reasons I
can't remember thought of one of the inkjet printers I'd brought home
after finding it waiting on the sidewalk. The first one I tried, I
think it was a Cannon, offered up a 24vdc switching supply. Ran the Powerbook
fine.

It seems odd that they'd start with such a voltage if they weren't using it
for something. Maybe the motors, but maybe the actual cartridge.

Michael

 

[Joel Kolstad]

I
would love to be able to figure out how to make the cartridge fire with
some simple electronics (its part of a much bigger curiosity I have
festering in my mind)...thanks!

The way an ink jet printer works is that a resistor is placed behind an ink
reservoir (and a hole in an aperature). You run current through the resistor,
an air bubble is formed behind the ink and pushes out a drop through the
aperature onto the page.

I expect that something like the old DeskJet 500 cartridges really were this
simple -- probably just a bunch of contacts going to the resistors. Newer
cartridges may have fancier matrixing arrangements and some now have digital
electronics that provide a unique serial number back to the printer. I don't
think it's around yet, but I wouldn't be surprised if in the not too distance
future there's a cryptographically secure link between the printer and the
cartridge that ensures that it's pretty much impossible for anyone to build,
refill, or simply _use_ the cartridges but the manufacturer or their
licensess.

Personally, if I wanted to play around with getting my own hobby projects
printing, I'd either (1) stick with the really old DeskJet 500-era
technologies or (2) get learn about USB and build a little box that makes one
of those dirt cheap cheapers like a DeskJet 3740 (all of $30 at Wally World)
have something like an RS-232 or I2C interface and behave line the old dot
matrix printers (start out in text mode accepting straight ASCII, use escape
codes to draw graphics line by line, etc). In fact, I'd wager there's even a
small market for a product like this -- it's nowhere near as nichey as the
"LCD backpacks" that have been popular enough there's a small handful of
people building them.

---Joel Kolstad