1080TI MINI FAN Tachometer Sensor Repair

Discussion in 'Electronics & Electrics' started by PRiME2007, Feb 5, 2020.

  1. PRiME2007

    PRiME2007 Member

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    Hello guys, I have this 1080TI mini videocard here atm that has no tachometer, I don't believe its a cable issue and can't do a RMA (out of warranty and at one point I cut and re-soldered the fan wires)

    I had this GPU connected to a watercooling system and the PCB tachometer connected to another control board which was meant to control the radiator fans, and it did, for a while. But it eventually stopped working and I was unable to get any RPM readings with software, and recently I've changed PC cases and put the 1080TI MINI back in its original HSF configuration to find the Tachometer does not work.

    Conclusion: The tachometer sensor on the GPU PCB is dead and I need to locate and replace it (I've done this sort of thing before and have a electronics workshop). Unfortunately I don't know much about GPU PCB so not completely sure where to start or how to test for which is faulty, I do know to follow the tachometer trace but the PCB is black and that is somewhat difficulty.

    Anyway thought I throw up a couple PCB photos in case by chance someone knows exactly which chips/resistors/diodes could be responsible and if its possible to test them (often difficult to test these things when soldered into a PCB).

    https://www.dropbox.com/s/9d8xp12i1d0099p/IMG_20200205_015313.jpg?dl=0
    https://www.dropbox.com/s/mhav517rupfpqka/IMG_20200205_015336.jpg?dl=0

    PS. I'm assuming the PWM connector is working because when I turn the PC on the GPU fan actually runs at the low IDLE speed, its just when entering windows (higher power state) its forced to max. Messing with MSI Afterburner does nothing.
     
    Last edited: Feb 5, 2020
  2. Agg

    Agg Lord of the Pings

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    What's the actual problem you're trying to solve? Does the card work ok? Can you run the fan off a normal mobo fan header instead?
     
  3. OP
    OP
    PRiME2007

    PRiME2007 Member

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    Yes the card works but the fan is STUCK on 100% when running in higher power mode (desktop environment). As for turbo fan header? off the motherboard? yes that should work but isn't what I want, the idea is to fix this RPM control/sensor issue because I do intend to sell the GPU at some point but can't really do that with the FAN stuck on %100.

    Note that loosing RPM control and having a forced %100 fan speed is a common fault I've found, but most people just RMA their videocard. That is no longer a option for me. (just out of warranty anyway)
     
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    PRiME2007

    PRiME2007 Member

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    Probably need to replace some transistor chips on the board, you know the ones like Q42 etc, 2 contacts on one side and 1 on the other.
    I'll need to look into if I can test those onboard via Multi-meter (I do have oscilloscope also but that shouldn't be needed)

    Sadly as with most electronics this finicky, not much help abouts.
     

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