Lenovo Thinkpad inverter questions

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  • Alohamora
    Member
    • Aug 2012
    • 37
    • USA

    #1

    Lenovo Thinkpad inverter questions

    I have a Thinkpad T61 with a dead inverter, well, I'm pretty sure it's the inverter and not the backlights but not 100%. I read somewhere that you could hold the probes from a frequency meter near the output of the inverter to check for output. Using this method, it's dead.

    So I purchased a replacement inverter and the replacement doesn't work either. I can see problems with the replacement when comparing the two. In 1-IMG 0213, the original is on top and the replacement below. In the set of pads labeled CP1 CP2 CP3, there's a solder blob on CP1 of the replacement that isn't present on the original. What's the function of these pads? I was thinking of removing the solder blob from CP1, but there's another problem on the replacement board. In 1-IMG 217-001, you can see that D1 looks cooked.

    I'm resigned to buying another inverter, but, if anyone has any advice on repairing I'd appreciate it.
    Attached Files
  • selldoor
    Slow Learner
    • Dec 2010
    • 7870

    #2
    Re: Lenovo Thinkpad inverter questions

    Have you checked the fuses on both boards

    You could test the diode? or take the one off the old board?

    I dont know what CP stands for - I will look later. You could check a few things like continuity across both halves and continuity the next point along the trace.
    Unless someone actually knows then you might as well remove the solder and try it - you can always put it back.

    You havent done pictures of the other ends of the boards are there plugs or wires straight off the transformers. Have you tested the secondary and primary windings?
    Please upload pictures using attachment function when ask for help on the repair
    http://www.badcaps.net/forum/showthread.php?t=39740

    Comment

    • selldoor
      Slow Learner
      • Dec 2010
      • 7870

      #3
      Re: Lenovo Thinkpad inverter questions

      I see from another post you have a dell monitor in pieces? Are the plugs on the panel lamps on that the same as on the inverter? If they are then you can test the inverter by setting it all up on the laptop and plugging in one/?two? of the lamps on the dell.

      Once the Dell is up and running you could similarly test the backlights on the
      laptop.by plugging them into the Dell inverter. They may only flash but that would be a sign they were not totally broken
      Last edited by selldoor; 08-18-2012, 02:34 PM.
      Please upload pictures using attachment function when ask for help on the repair
      http://www.badcaps.net/forum/showthread.php?t=39740

      Comment

      • Alohamora
        Member
        • Aug 2012
        • 37
        • USA

        #4
        Re: Lenovo Thinkpad inverter questions

        D1 is an LED and it's actually working OK on both boards.

        F1 on my original board is reading open, OK on board #2.

        I peeled off the cover to get a shot of the transformers.
        Both transformers are checking out the same

        about 1 ohm from pin 1 to pin 2

        I'm assuming that pins 4 and 5 (on the right hand side) are the secondary side, but those are reading open? Also open across the two pins of CN1. What sort of reading should I get on the secondary side?
        Attached Files

        Comment

        • Alohamora
          Member
          • Aug 2012
          • 37
          • USA

          #5
          Re: Lenovo Thinkpad inverter questions

          Originally posted by selldoor
          I see from another post you have a dell monitor in pieces? Are the plugs on the panel lamps on that the same as on the inverter? If they are then you can test the inverter by setting it all up on the laptop and plugging in one/?two? of the lamps on the dell.

          Once the Dell is up and running you could similarly test the backlights on the
          laptop.by plugging them into the Dell inverter. They may only flash but that would be a sign they were not totally broken
          There's a shield over the inverter on the Dell that I have not opened up. I'm a bit reluctant to mix and match between the laptop display and the desktop, I don't want to put too much voltage on the laptop backlight.

          Comment

          • selldoor
            Slow Learner
            • Dec 2010
            • 7870

            #6
            Re: Lenovo Thinkpad inverter questions

            Originally posted by Alohamora

            I'm assuming that pins 4 and 5 (on the right hand side) are the secondary side, but those are reading open? Also open across the two pins of CN1. What sort of reading should I get on the secondary side?
            Sorry dont know much about laptop inverters and what you get on CN1
            will depend on the values of the smd components. (I take it you mean
            resistance - dont recommend voltage - most likely blow your meter)

            To be sure about the transformer you will have to check the long way
            meter on ohms 2000 ( should be high enough)
            Test pin 1>2 1>3 1>4 1>5 Then 2>3 2>4 2>5 then 3>4 3>5 then 4>5
            Please upload pictures using attachment function when ask for help on the repair
            http://www.badcaps.net/forum/showthread.php?t=39740

            Comment

            • Alohamora
              Member
              • Aug 2012
              • 37
              • USA

              #7
              Re: Lenovo Thinkpad inverter questions

              pin 1 to 2 original = 1.0 replacement = 1.2 ohms
              pin 3 to 4 original = 860 replacement = 850 ohms

              All other pairs are open

              Comment

              • selldoor
                Slow Learner
                • Dec 2010
                • 7870

                #8
                Re: Lenovo Thinkpad inverter questions

                Originally posted by Alohamora
                pin 1 to 2 original = 1.0 replacement = 1.2 ohms
                pin 3 to 4 original = 860 replacement = 850 ohms

                All other pairs are open
                Well I think they look good - How about the cable? they have a hard life and damage easily?
                Please upload pictures using attachment function when ask for help on the repair
                http://www.badcaps.net/forum/showthread.php?t=39740

                Comment

                • Alohamora
                  Member
                  • Aug 2012
                  • 37
                  • USA

                  #9
                  Re: Lenovo Thinkpad inverter questions

                  Could be wiring. It turns out there are generic laptop CCFL backlights available on ebay pretty cheap, I think I will get one. Although I am really not eager to open up the LCD to try replacing it, at least with a test CCFL bulb, I'll know better where I stand.

                  Also, I did try removing the solder blob from CP1 of the replacement board. It didn't help.


                  I really appreciate your help, I'll let you know how it turns out.

                  Comment

                  • tibimakai
                    Badcaps Legend
                    • Jan 2012
                    • 3680
                    • USA

                    #10
                    Re: Lenovo Thinkpad inverter questions

                    it's highly unlikely that all the tubes are bad.

                    Comment

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