HP F4180 stopped working please help troubleshoot

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  • flat-earther
    Senior Member
    • Dec 2022
    • 107
    • palestine

    #21
    I removed the three electrolytic caps on the print head board and they measure good.

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    • flat-earther
      Senior Member
      • Dec 2022
      • 107
      • palestine

      #22
      I reassembled the printer, it was difficult because it has been months since I disassembled it so I didn't remember how to assemble it but I got it done and this disassembly video helped me https://www.youtube.com/watch?v=hgiCGBt-C3U

      Those ribbon cables are a nightmare, they are so thin and you have to push them in which makes them buckle, very bad design. I put silicone spray on one of them to try and make it go in easier.
      I sanded the cable and the plastic tab that fell off of two of them and superglued it back on.

      I powered up the printer and guess what, same error as before.

      Out of curiosity I measured the output(emitter pin) of the 16V NPN BJT while powering the printer up now that it's assembled, and it gradually went to -0.12V, what does that mean? I wonder why it went negative. at no point did it have 16V.
      Attached Files

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      • flat-earther
        Senior Member
        • Dec 2022
        • 107
        • palestine

        #23
        I removed the cover on the IC that's on the print head PCB, here's photos
        74C9TNTG4
        SN105117BPZP
        1525-0036
        Attached Files

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