Jacques Cousteau

Take a  journey through the fascinating undersea world of the Epson Stylus Pro Piezoelectric printhead.  You will see great, big, powerful looking things that few among us ever have.  Learn the flow of UltraChrome HDR ink as it travels through an X900 head.  Understand what a channel is, what a chamber is, what a nozzle is, and so much more.  Keep in mind as you explore this great new world, that all of it lives inside a space no thicker than your own fingernail.  That’s right, the THICKNESS of your fingernail..


The journey into the unknown begins


First off, here is an X900 printhead in various stages of autopsy, with key parts named.  This printhead is in a variety of stages of disrepair.  Starting from left to right, left being the farthest apart, right being completely together:


Take a close look at the above named parts.  Image-left shows the cut end of a micro ribbon cable.  This electrical cable houses all of the connections from the mother board to each and every individual chamber wall (360 per color) in each and every chamber of the piezoelectric nozzle board.  The image just below shows a chamber viewed from below, exposing all of the microscopic wires running to each chamber wall (nozzle).



This next illustration names key parts of the PIEZOELECTRIC BOARD which lives just below the face of the printhead, on the very top of each channel.  NOTE:  This entire micro machine measures .5mm from floor to ceiling!!!


The following image is an illustration of the top of a piezoboard, as if it’s being  seen through the eyes of a microscope.  The printhead face is theoretically removed, minus the nozzle openings which are essentially holes drilled in the face of the printhead:


The following images show just how small a chamber actually is.  More amazing still, the piezoelectric nozzle board in all of it’s entirety is just the tiny portion which sits on top!


This 4.7mm represents two things – the piezoelectric nozzle board, AND the chamber base plate below it


.5mm (thats, point 5mm) represents the thickness of the piezoelectric nozzle board.
This is nothing short of amazing.

I’d like to take this moment to give Epson some well earned credit.  Yes I know you hate Epson right now, but imagine that all of what you are about to experience, and all that has been argued about, criticized, bitched about forever and only rarely complimented for it’s sheer incredible-ness – operates inside something thinner than your finger nail.

The images below show not only a printhead face, with it’s tiny nozzle openings ready to fire – but they show what’s just below those tiny openings.


X900 printhead with face ON


X900 printhead with face OFF.   Daffy Duck points out the nozzle ports


Each channel in an X900 printhead fires two individual colors separately


Ink enters each channel through a port from below

This is a dreaded “Fatal Error” message head.  As you can see once you get a message like this, your head is dead.


The dreaded fatal error head. Note how the chamber walls, and floors have completely collapsed under the heat and pressure of ill-advised cleanings.

Once you get a visual on just how tiny a nozzle chamber is, it becomes rather amazing that they don’t clog every day all day.  Remember that a nozzle is fired when the piezoelectric chamber walls flex – squeezing ink out through the nozzle opening in the face of the head.  Once ink between the chamber walls starts to dry up it hardens.  Once it hardens the walls can’t flex.  Once the walls can’t flex they can’t fire ink, and they become vulnerable to overheating.



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  1. Kenneth Scheinberg said:

    I downloaded the instructional video for epson 7900 but I cannot find where this went on my computer. How do I bring this up again

    • Eric said:

      the video does not download, it streams. It’s hosted by Vimeo, you watch it in your web browser as many times as you like for 30 days. Open you browser and go back to where you rented it, then hit play.

    • Kenneth Scheinberg said:

      As you hinted in your video, I dropped the screw that attaches the printhead to the carriage. How do I find a replacement. I obviously could not find such a small screw. I called epson but they were no help.

  2. I found this article after googeling the error code 1a39 for Epson 4900.
    I had to post here because after mucking about by my self I found a solution that was kinda wierd.
    I started the printer, and held up the windowed lid while it started (pressed the “lid-sensor” button with a finger)
    When the carrige started to move I gave it a push agaist it direction. That forced the printer to crash without the “1a39”, and when I booted up again it worked just fine.

    To help other googlers:
    Epson stylus pro x900 4900 fatal error crash 1a39 solution on startup
    1A39 error code

  3. Peter Szalai said:


    I am in trouble with my printer, seems like my head is dead and has short circuit inside. ( 1A39 error code…) I had read a lot of Epson patent, learned how the heads works, and measured the signals with oscilloscope on FFC cables… I know, normal people give up here, but I want to know more about the problem… This page helped me a lot to understand these new TFP heads, but I am interested also: How looks like the PCB board on the back of the head. Is there any controller, driver chip on that PCB, or all the drivers integrated on the bottom of the head, and that PCB is only a connector holder? Can I get some pictures about that PCB and the backside of the head? It can help me a lot in my study. Thank you, Peter

    • Hi. I found a solution that helped me. Posted it above, but here it is again. 😛
      I started the printer, and held up the windowed lid while it started (pressed the “lid-sensor” button with a finger)
      When the carrige started to move I gave it a push agaist it direction. That forced the printer to crash without the “1a39”, and when I booted up again it worked just fine.

  4. Gitte de Sainte Marie said:

    On CompassMicro.com, they say that Epson nolonger allow sale of printheads to enduser customers … I would be interested in knowing what the price was if you remember. A technician told me yesterday that the printhead alone costs 1.200 € here in France which should be a little more in $.

  5. amit said:

    I have 7890 printer printer head is damage
    4900 printhead conplitable for 7890 printhead???

  6. André Denis said:

    Would a regular pattern, i.e. 10 good nozzles, followed by 2 bad nozzles, throughout the 360 nozzles, point to an electrical problem, instead of a ‘ink clogged’ problem?

    • Eric said:

      Thats the million dollar question

      • André Denis said:

        and i sure would like to know. That’s the difference between trying to clean it or dumping this printer. 4 months after end of first year warranty. Sure does not look like a random blotch of ink. More like decaying electric. Only Cyan. all others perfect.

  7. Scott said:


    I must have something blocking in there or damaged diaphram inside. Its back feeding ink up a different clear line from the head
    I use for printing film
    And nothing is printing out now at all

    I use two blacks and rest is clear whitchhazel in refill carts

  8. Scott said:

    can you take off the top teflon faceplate to clean under or will that ruin the head

    • GoGo said:

      theoretically yes, but in reality I would have to say no. I cannot see how you could align the holes up again, get the cage protecting the face off without destroying it beyond reassembly, or glue all those chamber walls back to the face without causing more problems than you might have solved. It’s a conundrum

  9. GoGo said:

    That second illustration is your ace in the hole Matt. Consider the nipples to be just below the hole in the deck where the ink flow arrow begins. Simple path up the reservoir and into each chamber, where you then have a better look coming from above – which is why I drew the third image. Once ink enters the chamber it travels between the walls and toward the nozzle opening in the printhead face (which is pictured in illustration #3). The problem is and always has been, considering clearing these X900 heads, that once the area between the chamber walls is compacted with dried ink, no cleaner can get to the meat of the clog. It can only get to either end of the clog, either from the inside of the channel via the nipple plate in the back of the head once it’s off, or through the face of the head by soaking it.

    I will work on creating another illustration, maybe there’s a way I can show all that goes on in just one image.

  10. Matthew Deegan said:

    Gives us a clear graphic and simple perspective from nipple to nozzle…….takes the mystery out of it and allows an intelligent calculation of where to go next

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