Lenovo li2341twf Monitor - No Power

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  • mikey32230
    Member
    • Jun 2013
    • 19
    • USA

    #21
    Re: Lenovo li2341twf Monitor - No Power

    Originally posted by budm
    The failure mode of the MLCC (Multi Layer ceramic Capacitor) type capacitor is shorted circuit, so try removing that cap and see if the low resistance will go away
    Okay, so just so I understand correctly.

    I am desoldering C702 and then... testing its resistance out of circuit?
    or am I powering the switchboard without the resistor in circuit?

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #22
      Re: Lenovo li2341twf Monitor - No Power

      Originally posted by mikey32230
      Okay, so just so I understand correctly.

      I am desoldering C702 and then... testing its resistance out of circuit?
      or am I powering the switchboard without the resistor in circuit?
      You will remove C702, and then you will take the resistance reading bewteen the two solder pads on the board where C702 used to be connected to to see if the low resistance is still exist on the board.
      If the shorts is n longer there without the cap, then you can power up the board for testing for now.
      C702 is a capacitor not a resistor.
      Last edited by budm; 08-19-2015, 11:09 AM.
      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

      • mikey32230
        Member
        • Jun 2013
        • 19
        • USA

        #23
        Re: Lenovo li2341twf Monitor - No Power

        Originally posted by budm
        You will remove C702, and then you will take the resistance reading bewteen the two solder pads on the board where C702 used to be connected to to see if the low resistance is still exist on the board.
        If the shorts is n longer there without the cap, then you can power up the board for testing for now.
        C702 is a capacitor not a resistor.
        Sorry, I wasn't thinking when I said that C702 was a resistor.

        Okay. I desoldered C702 and I still get 2.6-2.8 resistance between those solder pads.

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #24
          Re: Lenovo li2341twf Monitor - No Power

          Since that cap is more likely to be the Filter cap for VCC of that IC, unless the there is anything else that are connected in parallel with that C702, then the only left will be that IC is shorted.
          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

          • mikey32230
            Member
            • Jun 2013
            • 19
            • USA

            #25
            Re: Lenovo li2341twf Monitor - No Power

            Originally posted by budm
            Since that cap is more likely to be the Filter cap for VCC of that IC, unless the there is anything else that are connected in parallel with that C702, then the only left will be that IC is shorted.
            So what are my options at this point? Am I stuck because there is no way for me to get a replacement IC? I would love to keep pursuing this repair in anyway possible.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA

              #26
              Re: Lenovo li2341twf Monitor - No Power

              Well, we need the spec of the IC to see which pin is the VCC pin, or you can remove the IC and replace it.
              http://nl.aliexpress.com/store/produ...toreId=1771244
              or try EBAY.
              Last edited by budm; 08-19-2015, 01:52 PM.
              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

              • mikey32230
                Member
                • Jun 2013
                • 19
                • USA

                #27
                Re: Lenovo li2341twf Monitor - No Power

                Originally posted by budm
                Well, we need the spec of the IC to see which pin is the VCC pin, or you can remove the IC and replace it.
                http://nl.aliexpress.com/store/produ...toreId=1771244
                or try EBAY.
                So I have searched pretty thoroughly and I cannot find anything close to that IC part number. The link you listed is the closest I have seen.

                Is there anyway to "guess and check" for the VCC pin? Can I just replace it with the IC with the one in the link you provided? or will that not work because it is not the same part number?

                Comment

                • mikey32230
                  Member
                  • Jun 2013
                  • 19
                  • USA

                  #28
                  Re: Lenovo li2341twf Monitor - No Power

                  Originally posted by Porto
                  Maybe only some mosfet or voltage regulator has blown.


                  Is the fuse still good?

                  That monitor uses an external power supply, did you test it with your working monitor?

                  Do you have any advice at this point while budm is in surgery?

                  Comment

                  • mike in bremerton
                    New Member
                    • Jul 2017
                    • 3
                    • United States

                    #29
                    Re: Lenovo li2341twf Monitor - No Power

                    I know it has been a little while but did you ever get the answer to fix the problem?

                    Comment

                    • mikey32230
                      Member
                      • Jun 2013
                      • 19
                      • USA

                      #30
                      Re: Lenovo li2341twf Monitor - No Power

                      Originally posted by mike in bremerton
                      I know it has been a little while but did you ever get the answer to fix the problem?
                      A little while (6 years) later…

                      Unfortunately not. I probably still have the disassembled monitor laying around somewhere. I think I ended up desoldering something poorly, probably rendering whatever component useless, became too busy, forgot where I left off and gave up.

                      Sorry :/

                      Comment

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