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    Sony VAIO PCG-71211M - NO Backlight

    Discussion in 'VAIO / Sony' started by rcv211, Mar 4, 2013.

  1. rcv211

    rcv211 Newbie

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    Hi,
    I have no backlight on Sony PCG-71211M MBX-224 M960,
    I have measure the famous backlight fuse (F15 brown N) and it's OK along with any other fuse I found...
    The laptop had a broken CCFL screen and I replace it with a LED one plus converter, laptop worked for 2 days and now has no backlight, even when I connect old screen with inverter...
    The inverter connector has 10.5V on pins 5,6 and 0V on pins 3,4
    Anyone know a hint to look?

    Regards
     
    rcv211, Mar 4, 2013
    #1
  2. ngvuanh

    ngvuanh Notebook Deity

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    You could mess up your laptop.
    How did you replace CCFL with LED LCD panel.
    Have you done anything additionally to make LED LCD worked?
     
    ngvuanh, Mar 4, 2013
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  3. rcv211

    rcv211 Newbie

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    Hi
    I order a new LED with a CCFL to LED converter kit for my model from ebay...
    Of course I remove the backlight inverter as it was of no use with the new LED display, the converter took it's place...
    I can't remember if I remove the battery though during replacement, but it was working for 2 days with no problem.
    But after 2 days when I was moving the top cover back and forth while laptop was on, I got strange artifacts until I lost the backlight.
    Screen is working though as I can see images and colors but no backlight...
    I place the old screen back and it had no backlight either...
     
    rcv211, Mar 5, 2013
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  4. ngvuanh

    ngvuanh Notebook Deity

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    You should check inverter cable inside the LCD panel.
     
    ngvuanh, Mar 5, 2013
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  5. rcv211

    rcv211 Newbie

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    I check inverter cable with a multimeter at both ends, and all 6 cables seems OK...
    Well at first I'm trying to make it work as it was, working with old broken display and inverter so converter and new display is disconnected, but even if I connect the new kit the result it's the same..
    If there was a short-circuit wouldn't be a blown fuse somewhere?

    thanks..
     
    rcv211, Mar 6, 2013
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  6. ngvuanh

    ngvuanh Notebook Deity

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    Do you get 19.5V at inverter cable?

    Sent from my LT30at using Tapatalk 2
     
    ngvuanh, Mar 6, 2013
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  7. rcv211

    rcv211 Newbie

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    With battery on, measured with a multimeter one terminal at ground and other at each pin.
    pins 5 & 6 have 10.5V
    pins 3 & 4 have 0V (I believe those should output some volts but I got 0V)
    pins 1 & 2 have 0V ( I believe they are ground)

    At the end of the backlight inverter where LCD plug 0V

    Thanks for you help..
     
    rcv211, Mar 7, 2013
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  8. ngvuanh

    ngvuanh Notebook Deity

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    If laptop is off, pin 3 and 4 should read 0v.
    However, if laptop is on, 3 and 4 should read 3.3v. Pin 4 is for enable inverter.
     
    ngvuanh, Mar 7, 2013
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  9. rcv211

    rcv211 Newbie

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    Sorry for the late reply,
    I measured pins 3,4 while laptop was on
    pin 3 3.24V
    pin 4 0.17V

    It seems the enabler ain't working, but how to fix it?
    The fact that pin 4 output 0,17V and not 0V, does it mean that the fuse might been bad although it measure ok?

    Thanks again...
     
    rcv211, Mar 9, 2013
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  10. ngvuanh

    ngvuanh Notebook Deity

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    There is no fuse for inverter.
    The problem is now beyond what you can do.
    Basically, the new converter from inverter to led damaged the motherboard. This is your bad news but I am sorry to say though.

    Sent from my LT30at using Tapatalk 2
     
    ngvuanh, Mar 9, 2013
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  11. rcv211

    rcv211 Newbie

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    That is bad news indeed...
    Aren't there smt devices that I could replace to fix that, or to force somehow with a short-circuit to send 3.3V to pin 4?

    I found this schematics
    http://www.elvikom.pl/forum/obrazki/_f/f_0013401.jpg
    If I replace those 74LVC08APW ?
    I know I sound desperate, but who can blame me...

    thanks...
     
    rcv211, Mar 9, 2013
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  12. ngvuanh

    ngvuanh Notebook Deity

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    I'm not sure but it's worth to try if you can replace that chip.

    Sent from my LT30at using Tapatalk 2
     
    ngvuanh, Mar 9, 2013
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  13. rcv211

    rcv211 Newbie

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    Thanks,
    I'll search for part and let you know it goes...
     
    rcv211, Mar 10, 2013
    #13