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Lenovo T14 (AMD, gen1) over-voltage protection IC keeps dying.

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    Lenovo T14 (AMD, gen1) over-voltage protection IC keeps dying.

    My T14's (NM-C801) main USBC input keeps failing every few months. Initially, it worked fine for several years. The symptom is that once powered from the main USBC port using a 65W power brick, after some time (minutes, hours) charging will fail completely. Powering from the secondary (docking) USBC input still works. This laptop is basically always plugged in. The first time it happened, it took me a long time to find that the FPF2281 over-voltage IC for that USBC input was at fault. When the issue occurs, it will continuously reset power delivery negotiations with the power brick -- according to my FNB58. Relevant section from the schematics:

    Click image for larger version

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    I've replaced the IC several times already, initially with 4 aliexpress parts which were all bad/wrong/reused. I bought 7 of them from a trustworthy local supplier and these hold up for several months. The problem always reoccurs though, and I'm sick of replacing that chip every 3-6 months.. At first I blamed my docking station for the failure, but when I stopped using that the next chip died just the same.

    Has anyone seen this sort of issue before? I couldn't find if this is a common issue using google, and I have little experience with repairing USBC laptops. I'm at the point of just jumpering out this protection IC, since it's always plugged in anyway. I can't imagine it's dying because of voltage spikes from my power brick. The next device in the chain is the PD controller, which I have replaced a year ago as well (it wasn't the problem though).

    Cheers,

    Rob
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    #2
    When you say "it will continuosly reset pd negotiations with the power brick", are you still getting 20V at the USB-C port or does it stay at around 5V?

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      #3
      Originally posted by trepachka View Post
      When you say "it will continuosly reset pd negotiations with the power brick", are you still getting 20V at the USB-C port or does it stay at around 5V?
      It will swing back to 5V, then renegotiate 20V, then repeat the loop forever..

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        #4
        I would think having a failed OVP would result in 5v at USB-C port. Is it possible that the chip you installed is of poor quality with varying threshold? Hence, you get this forever loop with threshold constantly going over tolerances?

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          #5
          Hey, I just came across a T14 Gen 2 with a similar issue. Initially, it came due to a failed PU1801 chip. After replacing the chip, computer works fine off the dock USB-C port. When plugged into the charging USB-C port, as soon as voltage switches from 5V to 20V, the whole thing resets and repeats. I am going to follow your suggestion and jump the the OVP switch to see if indeed it is causing this issue.

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            #6
            Jumping the OVP switch did nothing. However, I replaced the TPS chip and the computer is working now.

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