Announcement

Collapse
No announcement yet.

HP Probook 470 G2 - white blinking - ADP_SIGNAL ?

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
    #1

    HP Probook 470 G2 - white blinking - ADP_SIGNAL ?

    Hello, I have this laptop with a bad motherboard. The LED in the socket is blinking white, endless loop. According to the information I found on the internet, this can be caused by several reasons that I am currently investigating.
    1. Damaged BIOS chip - it seems to be fine, CH341a programmer can read it
    2. BIOS RTC voltage shorted to ground - it seems to be fine, around 3V
    3. Damaged adapter identification circuit - I think there is a problem here, but please help explain the function
    What should be the voltage on ADP_SIGNAL when using a 65W HP adapter? My calculation of the voltage divider comes out to be around 2.6V if the PQA3 transistor is OFF. And what voltage should be on ADP_A_ID ?

    What is the function of PQA3? Limiting the maximal voltage - overvoltage protection? If I understand correctly, PQA3 opens if the ADP_SIGNAL voltage is about 3.6V, then the voltage between the base and the emitter is - 0.6V and the PNP transistor should open.

    Transistor PQA5 IS installed, its function is also unclear to me. I also don't understand what PQA1 does?


    Attached page 53 from schematics https://www.badcaps.net/forum/troubl...tic#post678633
    Page 53 Adapter connector
    2 Photos
    Tags: None
    #2
    Another, basic problem found. +1.05VSP short to GND

    Comment

      #3
      But this resistance from +1.05VSP to GND can be normal, not sure

      Comment

        #4
        Yes, this is probably the CPU vcore line and by design, the resistance will be low but no idea on what you are measuring for this rail.

        What is the exact resistace to ground in ohms of +1.05VSP?

        Comment

          #5
          +1.05 VSP to GND = 0.4 ohms according to my multimeter. I haven't tried removing the connection to +1.05VS by disconnecting jumper PJH1 yet.

          I have more details about the motherboard's behavior:
          Sometimes, maybe once or twice a day, it behaves more normally, the white LED on the power socket is constantly on, when the power adapter is disconnected and reconnected, it usually fails to repeat and the power socket diode flashes white again for an infinite time.

          I measured the voltage on ADP_SIGNAL in both cases:
          1. The diode is constantly on = 2.8 V. This corresponds to the calculated value according to the resistors in the diagram.
          2. The diode is blinking= 3.5 V

          The measured resistance from ADP_SIGNAL to ground is constantly about 62 k ohms, with the power adapter disconnected.

          This brings me back to wondering where the hell the fault is

          Comment

            #6
            Here is some knowledge about ADP_ID_CHK circuit https://www.badcaps.net/forum/troubl...14#post3460914

            Comment

              #7
              The notebook still resists, I have made further measurements, please give me further advice.

              BIOS chip replaced and new programmed - still same error
              Voltages and resistances to GND:
              • +5VDS - 5V - + 20 Kohm
              • +3VDS - 3.3V - 52 ohm, too low ?
              • +1.05VSP - 0V - 33 Kohm
              • +1.05VS - 0V - 0.3 ohm
              • +3VLP - 3.3V
              • +1.35VP - 0V - 1K ohm
              • 3V_PCH - 3V - 11 ohm
              • +RTCVCC - 3V
              • 5VS 0V - 12k ohm
              • 3VS 0V - 0.3 ohm
              When injecting 3VS I got up to 4A at about 2.5V, the only thing that was heating up on the board was the CPU
              • ADP_SIGNAL - 3.4V
              • ADP_A_ID - 2.8V
              When disconnecting R270 (ADP_A_ID to SIO pin 42), the voltage dropped to the expected value calculated from the voltage divider, about 1.8V. When connected back, the voltage increased to 2.8V again, so the voltage from SIO is penetrating here, the fault is more likely not in the ADP ID circuit
              • 3V_PG - 3V
              • DPWROK - 3.3V
              • PWR_GD - 0V
              • CHRG_ADP_DET 3.3V
              • ACDET pin 6 on PU102 2.6V
              • SLP_S4# 0V - 82 Kohm
              • SM_PG_CTRL 4V - 260 K
              • RSMRST 0V
              • SLP_SUS ?
              All these tested with multimeter seems ok:
              • PQA1
              • PQA3
              • PQA5


              PD1 disconnected from board, no change


              Whole board consumption is 20 - 30 mA

              Comment

                #8
                Multiple 3v rails are too low. They do mate with the cpu / pch. To me, the cpu is likely dead. Wait on other comments.

                Comment

                  #9
                  PQM1 possible short-circuit G to S, only 2 ohm. Or bad PUM1. PQM2 has G-S resistance about 1 Mohm. +1.35VP rail.

                  I ordered another motherboard for compare

                  Comment

                    #10
                    The 2nd board arrived for comparison, I haven't tried turning it on yet, measurements showed:

                    +5VDS - 5V - + 20 Kohm - same
                    +3VDS - 3.3V - 52 ohm -> 17kohm
                    +1.05VSP - 0V - 33 Kohm -> ?
                    +1.05VS - 0V - 0.3 ohm -> same
                    +3VLP - 3.3V
                    +1.35VP - 0V - 1K ohm -
                    3V_PCH - 3V - 11 ohm -> 15kohm
                    +RTCVCC - 3V
                    5VS 0V - 12k ohm -> same
                    3VS 0V - 0.3 ohm -> same

                    So the PCH in first boards seems to be dead. PQM 1 or PUM1 too

                    Comment

                      #11
                      The second board is also defective, but in different way.

                      Caps lock blink once
                      Power socket three times white
                      Power button does nothing, notebook does not turn on, but voltage on power button react correctly
                      Bios version M74, bios chip replaced, and flashed, still same

                      +1.05VS - resistance to ground is also 0.3 ohm. What is typical resistance value for PCH in intel 4. generation for this power rail ?

                      Comment

                      Previous template Next
                      Working...
                      X