After change screen no video

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  • MDY
    Senior Member
    • Jan 2014
    • 75
    • Spain
    #1

    After change screen no video

    Hi,

    After change screen maybe with battery on, no video on screen. I do have video on VGA out. Screen is LED 40 pins. What can I check on it? I do have 19V on LVDS cable.
    Tags: None
    • dj_ricoh
      Badcaps Legend
      • Jan 2013
      • 2073
      • uk
      #2
      Re: After change screen no video

      the cable its bad
      p.s. did you saw sparks? if not your ok. i know that case but it makes sparks then your f k

      if it makes sparks it will not even power
      Last edited by dj_ricoh; 01-23-2014, 02:14 AM.
      Just cook it! It's already broken.

        Comment

        • fddizon
          Badcaps Veteran
          • Sep 2011
          • 555
          • Philippines
          #3
          Re: After change screen no video

          dj,

          y sparks happen?

            Comment

            • dj_ricoh
              Badcaps Legend
              • Jan 2013
              • 2073
              • uk
              #4
              Re: After change screen no video


              i change the mobo then ( the problem then it had no backlight and i forgot the bat on)
              dude i`m sorry for you. if you manage to fix it i wanna work for you as a apprentice.
              Just cook it! It's already broken.

                Comment

                • lefos
                  Badcaps Veteran
                  • Nov 2013
                  • 321
                  • Greece
                  #5
                  Re: After change screen no video

                  Have you checked for any fuse near the lvds connector? Does it have picture but no backlight?

                    Comment

                    • kisk
                      Computer Tech
                      • Jan 2014
                      • 78
                      • USA
                      #6
                      Re: After change screen no video

                      What is the laptop model? Were you changing a cracked screen or a different screen with no picture?

                        Comment

                        • Francisco.s
                          Badcaps Veteran
                          • Jan 2013
                          • 686
                          • Spain
                          #7
                          Re: After change screen no video

                          Originally posted by MDY
                          Hi,

                          After change screen maybe with battery on, no video on screen. I do have video on VGA out. Screen is LED 40 pins. What can I check on it? I do have 19V on LVDS cable.
                          Probably the sio (embedded controller) has died. Usually the pins that control brightness, have no serial protector resistance, (connected directly) so current trough this pin became extremely high, destroying this sio output.
                          Try to cut this trace, and supply a fix 3,3v at connector brightness pin.
                          The schematic will help.

                            Comment

                            • MDY
                              Senior Member
                              • Jan 2014
                              • 75
                              • Spain
                              #8
                              Re: After change screen no video

                              Thanks to all for replay. I do have image, but no backlight.

                              I checked datasheet of screen LP156WH4 and I have:

                              pin2 3.3V
                              pin3 3.3V
                              pin4 3.3V

                              pin 36 (LED_EN) 0,26V
                              pin 38,39,40 - 19V

                              I think problem is pin 36 (LED_EN) 0,26V. I checked the same pin in motherboard and I have the same 0.26V
                              I think in this pin I should have 3V to enable backlight on/off, right??
                              Last edited by MDY; 01-27-2014, 04:33 AM.

                                Comment

                                • Th3_uN1Qu3
                                  Believe in
                                  • Jul 2010
                                  • 6031
                                  • Romania
                                  #9
                                  Re: After change screen no video

                                  Yes exactly. I have the exact same problem with a Lenovo X200 that someone brought in a couple days ago. The backlight died after a water spill on the board. I have managed to fix the 20v power trace (a fuse blown and some corrosion), but i have LED_EN shorted to ground, so still no backlight.

                                  I'll let you guys know if i manage to fix it.
                                  Originally posted by PeteS in CA
                                  Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                                  A working TV? How boring!

                                    Comment

                                    • Th3_uN1Qu3
                                      Believe in
                                      • Jul 2010
                                      • 6031
                                      • Romania
                                      #10
                                      Re: After change screen no video

                                      I did fix the Lenovo - i lifted the BACKLIGHT_ON (aka LED_EN) pin from the display connector and wired it to 3.3v from somewhere else on the board. The laptop lost ability to turn the screen backlight off but that's better than no backlight at all. It does turn off when the laptop is put into sleep or shut down, so that's good enough. It's back to the owner now.
                                      Attached Files
                                      Originally posted by PeteS in CA
                                      Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                                      A working TV? How boring!

                                        Comment

                                        • nickscott818
                                          Banned
                                          • Jan 2014
                                          • 6
                                          • UK
                                          #11
                                          Re: After change screen no video

                                          I had the same problem when I had replaced the sony vaio screen. It was not showing anything on the screen. I double checked the wires again found that the cable connecting to the mother board was out.

                                            Comment

                                            • MDY
                                              Senior Member
                                              • Jan 2014
                                              • 75
                                              • Spain
                                              #12
                                              Re: After change screen no video

                                              Hi Th3_uN1Qu3

                                              I found that pin 34 is System PWM Signal input for dimming and also has to have 3V

                                              By the way, what did you put on the cable to aislate?

                                                Comment

                                                • Th3_uN1Qu3
                                                  Believe in
                                                  • Jul 2010
                                                  • 6031
                                                  • Romania
                                                  #13
                                                  Re: After change screen no video

                                                  Hot glue.
                                                  Originally posted by PeteS in CA
                                                  Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                                                  A working TV? How boring!

                                                    Comment

                                                    • MDY
                                                      Senior Member
                                                      • Jan 2014
                                                      • 75
                                                      • Spain
                                                      #14
                                                      Re: After change screen no video

                                                      Originally posted by Th3_uN1Qu3
                                                      Hot glue.
                                                      Yesh, but do you use this one? http://www.leroymerlin.es/img/r25/04...2218640_ls.jpg

                                                        Comment

                                                        • Th3_uN1Qu3
                                                          Believe in
                                                          • Jul 2010
                                                          • 6031
                                                          • Romania
                                                          #15
                                                          Re: After change screen no video

                                                          Something like that.
                                                          Originally posted by PeteS in CA
                                                          Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                                                          A working TV? How boring!

                                                            Comment

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