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Lenovo T480s completely dead

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    #21
    Re: Lenovo T480s completely dead

    Docking station arrived, no power on the laptop at all. 0v on all pins
    With charger directly on laptop i get 5v on several pins of type c charger port.

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      #22
      Re: Lenovo T480s completely dead

      You stated earlier that you used the 0 filled TB bios? Did you try to write the T480s file as TB firmware?

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        #23
        Re: Lenovo T480s completely dead

        I flashed the 0 filled bios on TB bios chip (only 1MB)
        Can't flash the T480s bios on TB chip, TB chip has very low capacity, only 1 MB as i stated.

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          #24
          Re: Lenovo T480s completely dead

          I meant the TBT.ZIP file (and the T480S TBT.BIN file inside it) from the SMDFlea topic. It is 252KB size.

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            #25
            Re: Lenovo T480s completely dead

            No i didn't, i only flashed the 0 filled file from that topic.
            What do i miss here?

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              #26
              Re: Lenovo T480s completely dead

              Today i flashed it, no change. Still 5v on some pins of usb c instead of 20.

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                #27
                Re: Lenovo T480s completely dead

                Originally posted by Andreasbest View Post
                Today i flashed it, no change. Still 5v on some pins of usb c instead of 20.
                post the resistane to gnd on TBT_VBUS20 and USBC_VBUS20
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                  #28
                  Re: Lenovo T480s completely dead

                  TBT_VBUS20 right after PF1 fuse is 410mV
                  USBC_VBUS20 right after PF2 fuse is 5V

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                    #29
                    Re: Lenovo T480s completely dead

                    I think you can connect the charger to the docking port directly - does the value on PF2 change from 410mV to higher level? If also 5v then i would start to look towards PD controller, U222. If you have received the USB-C tester it would be nice to see how much current is drawn, my HP Elitebook for example can charge the battery from 5v USB charger when in off state. But not turn on from this adapter because of low wattage. If the lenovo can do it - then you can see if it charges and maybe even turn on from battery if left to charge for a while.
                    It is a lot of work to troubleshoot USB-C charging.
                    https://www.richtek.com/Design%20Sup...Document/AN056

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                      #30
                      Re: Lenovo T480s completely dead

                      Originally posted by khaahk View Post
                      I think you can connect the charger to the docking port directly - does the value on PF2 change from 410mV to higher level? If also 5v then i would start to look towards PD controller, U222. If you have received the USB-C tester it would be nice to see how much current is drawn, my HP Elitebook for example can charge the battery from 5v USB charger when in off state. But not turn on from this adapter because of low wattage. If the lenovo can do it - then you can see if it charges and maybe even turn on from battery if left to charge for a while.
                      It is a lot of work to troubleshoot USB-C charging.
                      https://www.richtek.com/Design%20Sup...Document/AN056
                      I'm still waiting for the tester.
                      The dock arrived with it's 90w psu, i connect it and the voltage on PF2 is still ~400mV

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                        #31
                        Re: Lenovo T480s completely dead

                        Originally posted by Andreasbest View Post
                        I'm still waiting for the tester.
                        The dock arrived with it's 90w psu, i connect it and the voltage on PF2 is still ~400mV
                        Check C299 and USBC_HV_GATE and TBT_HV_GATE voltage
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                          #32
                          Re: Lenovo T480s completely dead

                          C299 ~400mV
                          I checked USBC_HV_GATE @ PR46 (i hope it's correct part) 0v
                          Not sure where to measure TBT_HV_GATE, PR41 and PR45 are missing from the MB.

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                            #33
                            Re: Lenovo T480s completely dead

                            Either using USB-C or docking port, the 5V should be at PL1 or PL2 (the same VIN20_IN), is the 5V there? The charger BQ25700 is able to use that 5V input to boost it up and charge the battery, is it happening? Does the voltage rise on battery when charger is connected? If left for long to charge the pc should work normally on battery.

                            If the above is true then measure resistance on C300, C301, C9597, C9598 to GND, they should be similar and high resistance.

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                              #34
                              Re: Lenovo T480s completely dead

                              PL1 and PL2 have no voltage at all.
                              Also no voltage at all pins of battery connector (with battery connected)
                              Only place i see voltage around there is PF2 5V

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                                #35
                                Re: Lenovo T480s completely dead

                                Take resistance measurements relative to GND on U222 pins 5,7,30 - also on PL1, PL101, VSYS15. Look for abnormally low resistances.

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                                  #36
                                  Re: Lenovo T480s completely dead

                                  Hello! Sorry for the delay but i work away from bench most of the week.

                                  5@ 0v
                                  7@ 3.3v
                                  30@ 1.7v
                                  PL1@ 5.7Ω to the GND, both pins
                                  PL101@ infinity Ω to the GND
                                  VSYS15 (measure it at F1) @ infinity Ω to the GND

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                                    #37
                                    Re: Lenovo T480s completely dead

                                    Finally the USB Type C tester is here.
                                    Let me know what test you want exactly yo do.

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                                      #38
                                      Re: Lenovo T480s completely dead

                                      Leave the USB-C tester for now, you have low resistance on 20V line, try locating where the 5 ohms comes from, try removing PL1, PL2, if needed PR101. If you have lab psu and thermal imager then make use of them.

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                                        #39
                                        Re: Lenovo T480s completely dead

                                        I can use a bench PSU too, where exactly do you want to apply voltage?

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                                          #40
                                          Re: Lenovo T480s completely dead

                                          At first try to narrow the location down, remove PL1 - find at what part of it is still 5 ohms, depending on the result remove PL2, if needed remove PR101 also.

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