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Topic: Thermal Print heads (Read 2932 times) previous topic - next topic


Hi all, I have a thermal print head that i pulled out of a Dymo Labelwriter 400 printer. The printer was dead but the stepper motor and printhead are still in good working order. I was thinking of having a crack at bringing new life to it by interfacing it to my arduino. I understand the basics on how these things work, well correct me if i am wrong they just print a line then the stepper motor move the paper a fraction then prints another line. easy enough, just like any other printer :) Now controlling the stepper motor is an easy task, i just googled the parts of the original board and found that it uses a A3967 microstepping driver. happy days  :D but the print head is a hole other ball game. it only has one number on it "GK11C735" which google came up with nothing :(

It has a ribbon cable with 21 pins cumming out of it. Which, with me trying to reverse engineer the circuit board i don't think they are all used. I know it will print at a 300x300 pixels per square inch. So i am a little lost as to how these things work. i would of though you just send a certain about of volts down a pin and it would heat up at a corresponding point.

Any thoughts, anyone one tried to do something like this before? I have read somewhere that someone managed to control their Seiko printer with an arduino, but the was little to none information on how they did it.

Deviant085 :)

oh and to help illustrate what i am working with here, here are some pictures of the print head. :)


If you measure the actual printing area on the head, if its 2/3 of an inch, then likely you will have one pin for common and 20 segments of head that source current. Or one + pin and 20 current sink pins. IF it is either, one would guess that a shift register and some decent FETs could be used to control the unit.


i wonder how it got that 300 pixel resolution then. I'm inclined to think its in some sort of matrix configuration.


I had the same thought but quickly realized it would be easy. 2^20 = 1,000,000+


well yes, if it took a binary input, but its more than likely made of just resistors, and 300 pixels are not the same as 300 combinations of pixels.


I know it's a late reply, but maybe you have not given up just yet.

I have been playing with exactly the same kind of print heads, and have print head from a Dymo Labelwriter 320 and from a portable Facsimile machine. Both use the same principle.

By digging around, i found out the manufacturer of the DYMO print head, and by writing them a mail, telling them a lie about i had a big amount of them i bought cheap, and i needed the datasheet to use them in a small production, they agreed and gave me the datasheet  8)

Using these print heads are quite simple. You supply them with 5V logic, and when you want to print, you enable a 24V supply voltage, and start clocking in data in the shift registers - just like an 74HC595, just this one is a bit longer (1728 bits for the Facsimile unit) - you throw a latch and the data you just clocked in appears at the driver circuits, you send a strobe who pulses all the heating elements for a VERY brief period, you don't want to fry them.

According to the datasheet, the DYMO one draws 13,9 Amps when all 448 dots are pulsed, so you need to have a big cap across the 24V supply!!!

I have collected all i have regarding these printheads here: http://zapro.dk/div/printer/

I am in the process at looking at the signals closer with a logic analyser, and i am planning on writing some code for my Arduino to drive the units.

// Per.

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