MAcbook A1181 - No backlight

Discussion in 'MacBook' started by curlywurly6p, Mar 15, 2012.

  1. curlywurly6p macrumors newbie

    Joined:
    Mar 15, 2012
    #1
    Hi
    I am a newbie and ive searched these forums but cannot find any post that tells me exactly where this 'FUSE' that controls the backlight may be.

    Model is a Macbook A1181 (white plastic casing) core duo 1.8 (LCD screen)

    Originally the hinges had broken , so I bought replacements and fitted.
    Upon re-assembly, there is no backlight anymore ( No spills, etc)
    Purchased a new inverter, still the same.
    Screen IS WORKING as whilst it was up and running ( image very faint), I connected the lamp cables to another laptops inverter and it lit up and appeared as 'Normal'. But its getting its power from another inverter.

    Used a spare screen to connect to this inverter, and it does not power up the lamps - Hence why i bought a replacement inverter ---still the same.

    I hear members talking about a 'FUSE' ---

    Can anyone advise where the fuse is on this model ? (LCD screen)
    The inverter supply cable is OK ( interms of continuity) , but can anyone advise what voltages I should be getting on each pin & exactly how to test ?

    WHERE IS THIS DAM FUSE !!! LOL

    Thanks in advance ...
     
  2. logana macrumors 65816

    logana

    Joined:
    Feb 4, 2006
    Location:
    Scotland
    #2
    A1181 models don't have a fuse - the later Unibody does - so stop looking

    It may be the logic board but I would guess that it is more likely to be the short cable between the logic board and the inverter that is broken.

    You mention replacing the hinges but not the cable....
     
  3. curlywurly6p thread starter macrumors newbie

    Joined:
    Mar 15, 2012
    #3
    Are we 100% sure there is no FUSE ???
    And anyone know what the outputs of the inverter cable should be at the inverter socket (from main board)

    It was working fine, i just replaced the hinges.
     
  4. logana macrumors 65816

    logana

    Joined:
    Feb 4, 2006
    Location:
    Scotland
    #4
    100% sure !!

    The short black cable does break internally since it is wound round the lefthand hinge and gets moved about every time the laptop screen is opened and closed.

    If a new cable does not fix it then it may be a fault on the logic board but there is no fuse to replace.....
     
  5. falseadress macrumors newbie

    Joined:
    May 13, 2012
    #5
    Measure the voltages, it should be 12v on one of the inverter pinouts. It is the connector closest to the CD. Measure without inverter and measure with the inverter plugged in. sometimes theres no 12v at all sometimes the 12v just drops to 3v.

    Pin 1 is 12.6v
    pin 2 is gnd
    pin 3 is 5v
    pin 4 is pwm 3.3 ish v i think

    Measure all the voltages. They should be all there.

    A very dirty trick is to jump 12.84v from one of the FET's near the ram area, just poke on the tabs of the fets/transistors and find 12v and connect it to the 12 v line where the inverter should be. Becareful not to short anything out. A lan cable or usb cable is good to grab a wire from.

    If eveything goes right, it should power up the computer. (or maybe go poof and magic smoke) you might not have a sleep fucntion sometimes. If the board is dead and you have nothing to lose. Try it. Try searching
     
  6. fixitgood macrumors newbie

    Joined:
    May 19, 2012
    #6
    Thanks so much to falseadress for the hint about the voltages! I just successfully revived the backlight of a 2009 A1181 Macbook by determining that the logic board was not putting out 5V on pin 3, finding a 5V source on the logic board, and routing a wire from there to pin 3. Voila - let there be light. Wow! :)
     
  7. mykweb macrumors member

    Joined:
    Feb 4, 2011
    Location:
    Edinburgh
    #7
    Had the same issue on my macbook.

    Replaced the black ribbon cable to the invertor and Vola.. sorted. Mine was really worn, where the cable was around the hinge the black cable was a discoloured brownie grey colour.

    Mike
     
  8. wedgeman macrumors newbie

    Joined:
    May 24, 2011
    #8

    there are quite often two link chips (0 ohm resistors used as jumpers) which are quite close to the backlight connector.. often one of them burns.

    If you find one burned, you can just jump it from one pad to the other, and try it.. I usually use a tiny strand of wire, so it acts as a slow fuse.. have done this 20 + times with success on units which had a bad inverter cable (just be sure to replace the cable at the same time, or you'll ruin the board!!)..
     
  9. israelg2011 macrumors newbie

    israelg2011

    Joined:
    May 31, 2016
    #9
    I Have the same exact problem right now! Im not getting the 5 volts from pin 3. Can I ask where you got the 5V from? I have the schematic but I can't find the boardview at the moment.
     
  10. tgilcas macrumors newbie

    tgilcas

    Joined:
    Jun 20, 2016
    #10
    Hi, I tried changing inverter cable, inverted board with no luck, so i decided to check motherboard circuit and this is what i found.

    I have same problem but with 12.6 Pin 1 Voltage, Its giving me 2.81V i cant find were to get 12V from motherboard. I download A1181 Schematic and am trying to find were to get to 12v but i cant get it....

    Can u help me find it?

    heres the schematic
    [​IMG]
     
  11. tgilcas macrumors newbie

    tgilcas

    Joined:
    Jun 20, 2016

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