VAR00 LA-9201P short to ground

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  • bjhawfam
    Senior Member
    • Dec 2014
    • 144
    • United States
    #1

    VAR00 LA-9201P short to ground

    I initially had a short to ground ,, AND,, the power cord ( AC adapter ) light would turn off. I found the short on mosfet pq607 and replaced the bad N-channel mosfet. Now the charger stays on and this enables me a better chance to test with actual voltage. The next issue is no power, I get voltage in 20 volts,, and the power board receives 5 volts. Chips U3 and U4 are NOT getting power. Not sure where they pull the voltage from... I included the schematic, any help is appreciated.

    I found the shorted mosfet and now I have power to the board, I than found another short on a resistor on the power board. replaced the resistor and now I have lights to one side of the power board ( 2 boards off of the motherboard ) I am getting a chip q9 on the ul indicator board that gets very hot right when plugged in. I cannot find the cause for the rapid heating chip. any help? I posted this already wanting any advice that would help..
    Attached Files
    Last edited by bjhawfam; 07-09-2017, 01:55 PM. Reason: added schematic
    Tags: None
    • bjhawfam
      Senior Member
      • Dec 2014
      • 144
      • United States
      #2
      Re: VAR00 LA-9201P short to ground

      I took voltage readings at JLED1 20 PIN connection to the power board.
      pin 1 ,,, 0v
      pin 2 ,,, 5v
      pin 3 ,,, 5v
      pin 4 ,,, 0v
      pin 5 ,,, 0v
      pin 6 ,,, 0v
      pin 7 ,,, 3v
      pin 8 ,,, 3v
      pins 9, 10 , 11 ,,,, 0v
      pin 12 ,,, 3v
      pins 13, 14, 15 ,,, 5v
      pins 16, 17, 18, 19, 20 ,,, 0v

        Comment

        • bjhawfam
          Senior Member
          • Dec 2014
          • 144
          • United States
          #3
          Re: VAR00 LA-9201P short to ground

          this is the chip that gets hot...
          Attached Files

            Comment

            • bjhawfam
              Senior Member
              • Dec 2014
              • 144
              • United States
              #4
              Re: VAR00 LA-9201P short to ground

              THanks for the multitude of responses,,, was able to fix q9, another short in another resistor,,,, now the laptop leds come on blue and after about 30 seconds they go off.... Will dig around more...

                Comment

                • caspian
                  Badcaps Legend
                  • Oct 2015
                  • 1589
                  • Laptop
                  #5
                  Re: VAR00 LA-9201P short to ground

                  The technicians here are helpful but it takes about 5-10 hours to get a response.
                  Now, will the AC adapter's LED stay on?
                  are 3.3v and 5v and CPU_Vcore voltages present on the board?

                    Comment

                    • bjhawfam
                      Senior Member
                      • Dec 2014
                      • 144
                      • United States
                      #6
                      Re: VAR00 LA-9201P short to ground

                      I understand it takes time for a response, and, thanks for responding. Yes, after finding the short to ground on the mosfet (replaced ) the power adapter now stays on.. That problem is now solved, however, I noticed there was no activity or L.E.D.S when plugged in. I found 2 shorted resistors on the indicator (led board) I replaced them and now the leds light up and I now have 3v and 5v into U3 and U4. That leads me to believe I now have a working power button... I took and break and will check for more issues in a few. I did see that some of the headache was from the previous owner's damage to the ribbon cable that leads from the motherboard into the powerboard ( also replaced ).. Now as it stands, I have power 20v in and power to the led board and power-on -button board.... The laptop still will not boot/post... Will check some more...

                        Comment

                        • caspian
                          Badcaps Legend
                          • Oct 2015
                          • 1589
                          • Laptop
                          #7
                          Re: VAR00 LA-9201P short to ground

                          before continuing with the power-button board, please check which voltage rails are not present on the main board.

                            Comment

                            • bjhawfam
                              Senior Member
                              • Dec 2014
                              • 144
                              • United States
                              #8
                              Re: VAR00 LA-9201P short to ground

                              3v and 5v are present currently......

                                Comment

                                • caspian
                                  Badcaps Legend
                                  • Oct 2015
                                  • 1589
                                  • Laptop
                                  #9
                                  Re: VAR00 LA-9201P short to ground

                                  after you press the power botton, check the following voltages:
                                  +VGA_CORE, +VCC_CORE, +1.5VSP, +1.05VP, +1.35VP

                                    Comment

                                    • bjhawfam
                                      Senior Member
                                      • Dec 2014
                                      • 144
                                      • United States
                                      #10
                                      Re: VAR00 LA-9201P short to ground

                                      I checked the voltages on the main board all 0
                                      1.5VSP= 0
                                      1.05VP = 0
                                      1.35VP= 0
                                      VGA AND VCC = 0

                                        Comment

                                        • caspian
                                          Badcaps Legend
                                          • Oct 2015
                                          • 1589
                                          • Laptop
                                          #11
                                          Re: VAR00 LA-9201P short to ground

                                          check pin 2 of D26 to see if there is any instant voltage triggering when you press the power button.
                                          measure pin 2 of R58 too.
                                          Last edited by caspian; 07-12-2017, 01:51 AM.

                                            Comment

                                            • bjhawfam
                                              Senior Member
                                              • Dec 2014
                                              • 144
                                              • United States
                                              #12
                                              Re: VAR00 LA-9201P short to ground

                                              Hello, Thanks for the advice.. Pin 2 on D26 power button is 3 volts the resistor on the same rail is 3 volts in and out,,,,,,,.... the only change is a voltage drop while holding sw1 down, other than that the 3v is present.
                                              Last edited by bjhawfam; 07-12-2017, 08:59 PM.

                                                Comment

                                                • bjhawfam
                                                  Senior Member
                                                  • Dec 2014
                                                  • 144
                                                  • United States
                                                  #13
                                                  Re: VAR00 LA-9201P short to ground

                                                  Im also picking up 10v? from pu100?

                                                    Comment

                                                    • caspian
                                                      Badcaps Legend
                                                      • Oct 2015
                                                      • 1589
                                                      • Laptop
                                                      #14
                                                      Re: VAR00 LA-9201P short to ground

                                                      Originally posted by bjhawfam
                                                      Im also picking up 10v? from pu100?
                                                      at which pin of pu100?

                                                        Comment

                                                        • caspian
                                                          Badcaps Legend
                                                          • Oct 2015
                                                          • 1589
                                                          • Laptop
                                                          #15
                                                          Re: VAR00 LA-9201P short to ground

                                                          what voltages do you measure at PL101 and PL102?

                                                          what does the laptop do after pressing the power button?

                                                            Comment

                                                            • bjhawfam
                                                              Senior Member
                                                              • Dec 2014
                                                              • 144
                                                              • United States
                                                              #16
                                                              Re: VAR00 LA-9201P short to ground

                                                              sorry pu200 pin 9 is 10 volts...

                                                                Comment

                                                                • bjhawfam
                                                                  Senior Member
                                                                  • Dec 2014
                                                                  • 144
                                                                  • United States
                                                                  #17
                                                                  Re: VAR00 LA-9201P short to ground

                                                                  After pressing power button ,,,,, nothing happens ,, no fan ,, no change in leds,,, nothing

                                                                    Comment

                                                                    • bjhawfam
                                                                      Senior Member
                                                                      • Dec 2014
                                                                      • 144
                                                                      • United States
                                                                      #18
                                                                      Re: VAR00 LA-9201P short to ground

                                                                      pl102 inductor is 5v,,,,,, pl101 3v
                                                                      Last edited by bjhawfam; 07-12-2017, 10:20 PM.

                                                                        Comment

                                                                        • caspian
                                                                          Badcaps Legend
                                                                          • Oct 2015
                                                                          • 1589
                                                                          • Laptop
                                                                          #19
                                                                          Re: VAR00 LA-9201P short to ground

                                                                          now measure pin114 and pin106 of KB9012 when you press the power button.
                                                                          Last edited by caspian; 07-12-2017, 10:29 PM.

                                                                            Comment

                                                                            • bjhawfam
                                                                              Senior Member
                                                                              • Dec 2014
                                                                              • 144
                                                                              • United States
                                                                              #20
                                                                              Re: VAR00 LA-9201P short to ground

                                                                              okay i will check
                                                                              Last edited by bjhawfam; 07-12-2017, 10:38 PM.

                                                                                Comment

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