thread top ad

Collapse

Announcement

Collapse

READ BEFORE REGISTERING SO YOUR ACCOUNT WORKS

In order for your account to be activated INSTANTLY, your PayPal email MUST MATCH THE EMAIL YOU USE TO REGISTER YOUR ACCOUNT ON THIS FORUM!! If your PAYPAL email address differs from your FORUM email address, your account will have to be activated MANUALLY when a customer service agent gets around to it.

I realize this sucks, and I do apologize.
See more
See less

[SOLVED]820-2850 no backlight

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

  • #16
    But need to understand what screen expect from board to turn on LEDs? Which signals? In laptops expect 12-19V, PWM and enable. And in apple?

    Comment


    • #17
      25V is not that low but it could be higher.
      On a working 2010 15" BKL output is 33V and LED return lines are 3.2V so that puts about 30V across the LEDs

      Comment


      • #18
        And how do you think these LED driver got burn? This is second macbook pro for 2 weeks. One is 2010 15, and another 2012 15
        Both of them working good, video, backlight. I just opened them to replace a cap and after that backlight is gone. In both cases I found hole in LP8545
        I dont know what wrong I do...why this led driver just got damage. In first case board 2012 I just replaced it and it works good.

        Comment


        • #19
          I have no idea, but you are shoving 2012 connectors into 2010 boards.

          Comment


          • #20
            About PWM, when it change from 2.2V to 2.5V this should increase VLED from 25V to 30V?

            Comment


            • #21
              No idea, 2.5V seems low. We can talk about this all day but you need to swap the LP8545 and check all resistors.

              Comment


              • #22
                Will replace LP8545 again and will compare with another board I have here for parts.
                It is possible to test screen connecting 30V to VLED directly? Will turn on the leds or it is no enought? This way also I can check if leds turn on at 27,28 or 29V

                Comment


                • #23
                  Negative to LED return lines and positive to the BKL Vout. LEDS should light at about 30V. But do this with a variable power supply and go up from 20V till they light up.

                  Comment


                  • #24
                    Sorry, you mean I have to put all 6 return lines to negative? And PPVOUT_S0_LCDBKLT to power supply. 20-30V

                    Comment


                    • #25
                      Why do you even want to mess with this? This is not going to fix the board. I gave you the correct voltages from the board.

                      Comment


                      • #26
                        Finally I got this board working. Resume: I found LP8545 damage and no backlight. After I replaced this IC with new one I got only 25V and no backlight. I replaced it again with new one same provider and again only 25V and no backlight. I replaced it again and the same. Always check carrefuly how this chip is solder and I solder this chip perfectly.

                        Then I took this chip from my board for parts and now backlight works and I have 33V

                        New chip from SEE-IC I got is written on it: VM08AD 45-EXTF. This chip doesnot work for me. I got only 25V with this chip. Could be fake chip? Or not exact part number they sent to me?

                        Comment


                        • #27
                          These chips have en EEPROM inside. Maybe they are programmed for something. A blank default EEPROM normally works.

                          Comment


                          • #28
                            Never find a not working new chip?

                            Comment


                            • #29
                              I don't buy these new chips, enough donor boards in the pile.

                              Comment

                              thread bottom ad

                              Collapse
                              Working...
                              X