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

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

    Leave a comment:


  • MDY
    replied
    Never find a not working new chip?

    Leave a comment:


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

    Leave a comment:


  • MDY
    replied
    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?

    Leave a comment:


  • dukefawks
    replied
    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.

    Leave a comment:


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

    Leave a comment:


  • dukefawks
    replied
    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.

    Leave a comment:


  • MDY
    replied
    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

    Leave a comment:


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

    Leave a comment:


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

    Leave a comment:


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

    Leave a comment:


  • MDY
    replied
    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.

    Leave a comment:


  • dukefawks
    replied
    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

    Leave a comment:


  • MDY
    replied
    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?

    Leave a comment:


  • dukefawks
    replied
    I have no idea. Compare the 25V to another 15" machine. It could be bad solder or dead LP8545 again. Check resistors around the LP8545 and check if no components were moved/blown off while replacing LP8545.

    Leave a comment:

thread bottom ad

Collapse
Working...
X