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Hacking an Inkjet Printer

Discussion in 'Electronic Design' started by MMS, Aug 26, 2005.

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  1. MMS

    MMS Guest

    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!

  2. Tom

    Tom Guest

    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.
  3. Guest

    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.
  4. 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

    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.

  5. Joel Kolstad

    Joel Kolstad Guest

    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

    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
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