Announcement

Collapse
No announcement yet.

Thinkpad T60 display, first no backlight, now nothing (long story and pictures inside

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Thinkpad T60 display, first no backlight, now nothing (long story and pictures inside

    I have an old T60 where the display was showing the "red haze" indicating the CCFL was on its way out. Eventually it developed a condition where upon a fresh reboot the display would be fine for a few minutes, and then the back light would go out. Plugging an external display into the VGA port showed the laptop was still working fine.

    I ordered a new screen, an AU Optronics 14.1" 30pin Matte LCD Screen B141XG09. I disassembled the laptop to prepare for the screen swap. When the screen showed up, the white plug was not the right kind to fit into my inverter. So I cut the connector off my broken screen, cut the connector off the new screen, and soldered my old connector on. When I wired everything up, the backlight would come on but the display was just a smear of colors. After messing with it a bit more, eventually the backlight stopped coming on, BUT the image now displayed correctly (you could barely see if by shining a bright light on the screen)

    So I thought the screen I bought was just bad, so I bought another one. This one had a connector that DID fit my inverter so I was able to try it out of the box, but the backlight never turned on, but the display again was barely visible by shining a bright light on the screen.

    If I switch the inverter with another inverter I get an error code beep (1 long, 2 short) and the laptop will not boot.

    So I broke out the multimeter and started poking around. See the image and letters, here is what I found

    A: With the laptop plugged in I was getting 20v here, as expected

    B: Same as A, I get 20v here as expected

    C: I get 20v at one end of the capacitor, so I know power is getting to the board

    D: Each of the legs of these transistors are all showing ~19v

    E: Initially, none of these were showing any voltage (or negligible mV). I think these are fuses? They all test as having continuity

    F: This looked like a large fuse, this was getting 19V on one end, 0 on another, and was not showing continuity, so I figured it was blown

    G: This is where the laptop screen cable plugs in. I checked all the pins for voltage and got negligible voltage, a few were showing 3.5v which I believe are the LCD comm channels, but nothing was getting the 19-20v I think it should.

    Now, the odd stuff. As I was checking out G, there was one time where I did find 19v on one of the pins. I have no idea why it tested different that one time. I hooked up the screen, turned the laptop on, and this time I got no backlight and no picture. Just totally dead.

    So I decided to bypass the fuse F. I soldered a wire between the 2 contacts and took fresh measurements. I was now getting 20v on pin 12 of the video connector. I was also getting 19-20v at all of the E points. I connected the monitor, and check the connector that plugs into the inverters, and was getting 20v on a couple of those pins. I plugged it into the inverter and tested around that board and I was getting 20v on the inverter. So it seemed power was finally getting to the inverter. I get the screen hooked up, turned the laptop on, and again, no backlight, not display.

    Now when I test I no longer get 20v on the 12 pin of the video connector (and thus no 20v all the way down to the inverter). Also all the spots marked E are now showing negligible voltage. I looked for any fuse I could find anywhere, every one I see around the board measures good.

    I tried an external screen on the VGA connector and that still works just fine, so there is still video output on that and the laptop is still working besides the screen.

    At this point I don't know where to go next, I found schematics online for the T60 but don't know how to read them. Any ideas?

    Here's the picture of the board with the letters showing the areas I am talking about

    Attached Files

    #2
    Re: Thinkpad T60 display, first no backlight, now nothing (long story and pictures in

    Anyone?

    Comment


      #3
      Re: Thinkpad T60 display, first no backlight, now nothing (long story and pictures in

      do these sample measurements exist?
      Attached Files
      I'm not happy to be so strong. because it's not humanly

      Comment


        #4
        Re: Thinkpad T60 display, first no backlight, now nothing (long story and pictures in

        Originally posted by Sametbey View Post
        do these sample measurements exist?
        So my inverter looks a little different, it's a push down plug with more than 4 pins, but when I had the 20v working on the board, I was getting 20v on one of the pins of the inverter. I did not check the output pins to the LCD

        Now, I am getting nominal/no voltage on the inverter pins OR on the output pins to the LCD.

        Comment


          #5
          Re: Thinkpad T60 display, first no backlight, now nothing (long story and pictures in

          inverter input pins can be different. 1 - 2 pin 20v, 3 pin BL, 4 pin ON, 5 - 6 pin GND. if no voltage comes up, there may be a fuse near the lvds panel socket on the motherboard. check. in the picture, the parts with the E Code must be a fuse.
          I'm not happy to be so strong. because it's not humanly

          Comment


            #6
            Re: Thinkpad T60 display, first no backlight, now nothing (long story and pictures in

            Originally posted by Sametbey View Post
            inverter input pins can be different. 1 - 2 pin 20v, 3 pin BL, 4 pin ON, 5 - 6 pin GND. if no voltage comes up, there may be a fuse near the lvds panel socket on the motherboard. check. in the picture, the parts with the E Code must be a fuse.
            All of the E's are showing no voltage but do have continuity. There may be a blown fuse I have not found yet.

            What would be causing these fuses to blow though?

            Comment


              #7
              Re: Thinkpad T60 display, first no backlight, now nothing (long story and pictures in

              Some of the fuses may be resettable ones. Its never a good idea btw to use a wire instead of a fuse. Do you have a schematic for the board,whats the FRU part number,and the FRU part number for the inverter and the original panel. A new panel will not not work unless it has the correct IBM/Thinkpad EDID.
              All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

              Comment


                #8
                Re: Thinkpad T60 display, first no backlight, now nothing (long story and pictures in

                Originally posted by SMDFlea View Post
                Some of the fuses may be resettable ones. Its never a good idea btw to use a wire instead of a fuse. Do you have a schematic for the board,whats the FRU part number,and the FRU part number for the inverter and the original panel. A new panel will not not work unless it has the correct IBM/Thinkpad EDID.


                I will look up the part FRU's

                I was asking thinkpad owners what panels they had used and they recommended the one I bought so I guess I assumed it would work.

                How do you reset a re settable fuse? If I get it working I will be replacing the jumpered fuses with actual ones.

                Comment


                  #9
                  Re: Thinkpad T60 display, first no backlight, now nothing (long story and pictures in

                  OK, more weirdness

                  So I got a new screen in, this one is a Samsung (vs the AU Optronics I had been trying). I plugged in the motherboard, and somehow, despite it not showing voltage before, and me not doing anything to the board, it was correctly registering 20v at the display plug. Umm, OK I thought

                  I plug in the cable, and I get 20v at the inverter connector. Great. I plug in the inverter, but get no voltage on that. I look around and find a fuse on the inverter that measures blown. So I jumper that fuse with a piece of copper wire, and now I get 20v on the inverter board. Great

                  So I plug in the Samsung screen into the inverter, and turn the motherboard on, and immediately a chip on the inverter literally burst into flames. That was exciting.

                  As luck would have it I have a spare inverter, and on that inverter the fuse was good. So I plug the new inverter into the ribbon cable. and I am getting 20v all the way to the inverter board. Great. I plug in the screen, and with a cup of water handy, turn the laptop on. No smoke, no flames, but also no picture and no backlight. So I go back to check the voltages, and now I'm getting no voltage along that 20v line anymore. But every single fuse along that power circuit tested fine. All the fuses on the motherboard, the fuse on the inverter (that had blown on the other inverter) all show continuity

                  I am completely dumbfounded how the board appeared to magically fix itself, detonated an inverter, then lost all power to the new inverter when it was turned on again. Is this thing cursed? Any ideas?
                  Last edited by SluggerB; 01-23-2021, 12:55 PM.

                  Comment

                  Working...
                  X