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Tefal GV8962 Pro Express steam iron - no power

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    #61
    Re: Tefal GV8962 Pro Express steam iron - no power

    Originally posted by CapLeaker View Post
    I think C7 may be shorted too. Take it out and remeasure it out of circuit.
    OK, I think it will mostly likely be a destructive removal..
    Last edited by beetle1303; 10-29-2020, 08:03 PM.

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      #62
      Re: Tefal GV8962 Pro Express steam iron - no power

      Originally posted by budm View Post
      Now check the resistance between GND and VCC pins of the IC's.
      Hmm.. I missed out the most devastating part when remove U2 without the right tools - the black material cracked into pieces when I tried hard to remove it with a soldering iron and a tweezer...

      So, ya, can't do any test on U2
      Last edited by beetle1303; 10-29-2020, 09:29 PM.

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        #63
        Re: Tefal GV8962 Pro Express steam iron - no power

        I am talking about the two IC's that you found the spec sheet to get the VVC pins, check the resistance of those VCC pins.
        BTW, since you cannot do SMD repair so it is a moot point to keep trying to fix the board.
        Never stop learning
        Basic LCD TV and Monitor troubleshooting guides.
        http://www.badcaps.net/forum/showthr...956#post305956

        Voltage Regulator (LDO) testing:
        http://www.badcaps.net/forum/showthr...999#post300999

        Inverter testing using old CFL:
        http://www.badcaps.net/forum/showthr...er+testing+cfl

        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
        http://s807.photobucket.com/user/budm/library/

        TV Factory reset codes listing:
        http://www.badcaps.net/forum/showthread.php?t=24809

        Comment


          #64
          Re: Tefal GV8962 Pro Express steam iron - no power

          Originally posted by CapLeaker View Post
          I think C7 may be shorted too. Take it out and remeasure it out of circuit.
          I took out C7 - off circuit fluctuated between 3.8 - 14 uF, probably the contact points are somewhat damaged... The resistance between the 2 C7 pads reads 20.8 ohm, same reading with the C7 in circuit.

          Comment


            #65
            Re: Tefal GV8962 Pro Express steam iron - no power

            Originally posted by budm View Post
            I am talking about the two IC's that you found the spec sheet to get the VVC pins, check the resistance of those VCC pins.
            BTW, since you cannot do SMD repair so it is a moot point to keep trying to fix the board.
            The resistance of those 2 ICs are both 20.8 ohm. After removed C7, same reading.

            Yes, indeed it will be purely academic from now on. And if there is any further fault finding worthwhile, it can only be done with SMD removal, and not restoring as I am not equipped and not capable.

            At this juncture, I want to thank you both, BUDM and CapLeaker, for spending time coaching me. It's been a pleasure learning under your coaching.

            Thank you very much.

            Comment


              #66
              Re: Tefal GV8962 Pro Express steam iron - no power

              Originally posted by beetle1303 View Post
              The resistance of those 2 ICs are both 20.8 ohm. After removed C7, same reading.

              Yes, indeed it will be purely academic from now on. And if there is any further fault finding worthwhile, it can only be done with SMD removal, and not restoring as I am not equipped and not capable.

              At this juncture, I want to thank you both, BUDM and CapLeaker, for spending time coaching me. It's been a pleasure learning under your coaching.

              Thank you very much.
              So pin1 of U2 is the Output pin for feeding VCC for the IC's.
              You can try removing C7 first to see if the resistance will go up or not, there are also other filter caps connected to this VCC line that have to be checked, worst case will be that the IC's are damaged.
              Never stop learning
              Basic LCD TV and Monitor troubleshooting guides.
              http://www.badcaps.net/forum/showthr...956#post305956

              Voltage Regulator (LDO) testing:
              http://www.badcaps.net/forum/showthr...999#post300999

              Inverter testing using old CFL:
              http://www.badcaps.net/forum/showthr...er+testing+cfl

              Tear down pictures : Hit the ">" Show Albums and stories" on the left side
              http://s807.photobucket.com/user/budm/library/

              TV Factory reset codes listing:
              http://www.badcaps.net/forum/showthread.php?t=24809

              Comment


                #67
                Re: Tefal GV8962 Pro Express steam iron - no power

                Originally posted by budm View Post
                So pin1 of U2 is the Output pin for feeding VCC for the IC's.
                You can try removing C7 first to see if the resistance will go up or not, there are also other filter caps connected to this VCC line that have to be checked, worst case will be that the IC's are damaged.
                I have already removed C7 and the resistance remains unchanged at 20.8Vdc. I have also attempted to trace and measure all the caps an resistors leading to the Vcc of the 2 ICs. Not surprisingly, I do not know what I was doing... But I feel the resistance pretty much measured 20.8Vdc in most places along the trace.

                I reckon that this would not go very far to determining what else is faulty beside the now apparent U2 being blown opened. But suffice to say replacing the R1 with a 5W 100 ohm was a MAJOR MISTAKE!! Nonetheless, it has been very educational, and I want to thank you (and CapLeaker) once again for patiently guiding me alone this learning journey.

                Thank you.

                Comment


                  #68
                  Re: Tefal GV8962 Pro Express steam iron - no power

                  Originally posted by beetle1303 View Post
                  I have already removed C7 and the resistance remains unchanged at 20.8Vdc. I have also attempted to trace and measure all the caps an resistors leading to the Vcc of the 2 ICs. Not surprisingly, I do not know what I was doing... But I feel the resistance pretty much measured 20.8Vdc in most places along the trace.

                  I reckon that this would not go very far to determining what else is faulty beside the now apparent U2 being blown opened. But suffice to say replacing the R1 with a 5W 100 ohm was a MAJOR MISTAKE!! Nonetheless, it has been very educational, and I want to thank you (and CapLeaker) once again for patiently guiding me alone this learning journey.

                  Thank you.
                  At least you gin the knowledge. One of the weak point of Buck converter is that when the pass device (I.E. MOSFET) shorted out, the input Voltage will be dumped into the load and can cause lots of damaged, they should at least put crowbar and a fuse on the output.
                  Never stop learning
                  Basic LCD TV and Monitor troubleshooting guides.
                  http://www.badcaps.net/forum/showthr...956#post305956

                  Voltage Regulator (LDO) testing:
                  http://www.badcaps.net/forum/showthr...999#post300999

                  Inverter testing using old CFL:
                  http://www.badcaps.net/forum/showthr...er+testing+cfl

                  Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                  http://s807.photobucket.com/user/budm/library/

                  TV Factory reset codes listing:
                  http://www.badcaps.net/forum/showthread.php?t=24809

                  Comment

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