Previous 1 10 11 12 13 14 Next 202 Replies Latest reply: Jan 24, 2015 11:45 AM by Sunfiresaturn Go to original post Branched to a new discussion.
  • mrbofus Level 1 Level 1 (5 points)

    Bad news on my end.  A few days ago, the iMac monitor started turning off again, with increasing frequency, until it just wouldn't come back on.  Took the iMac in to the Apple Store and they said it was probably the LCD.  Talked to them on the phone later that night, and it turns out replacing the LCD didn't fix the issue, so it was the logic board.  Given that it was going to cost about $830 for the logic board replacement (about $730 for the part, plus labor and tax), I opted to not replace the logic board. 

     

    Anyways, hopefully this isn't the case for the rest of you guys (or if it is, you got Apple Care)!

  • Jah_Daffodil Level 1 Level 1 (0 points)

    Hello ! They did not think it could be the power supply unit ? It´s cheaper to replace...

     

    A.

  • drunknmonk Level 1 Level 1 (0 points)

    mrbofus, if the mac will switch on and you have a thunderbolt port, you can run a second display of the mac, thats what im doing.

  • mrbofus Level 1 Level 1 (5 points)

    Jah_Daffodil wrote:

     

    Hello ! They did not think it could be the power supply unit ? It´s cheaper to replace...

     

    A.

     

    No, they said it was the logic board.

  • mrbofus Level 1 Level 1 (5 points)

    drunknmonk wrote:

     

    mrbofus, if the mac will switch on and you have a thunderbolt port, you can run a second display of the mac, thats what im doing.

     

    Yeah, an external monitor works fine.  But not having the built-in display work ***** #*$&.

  • Jah_Daffodil Level 1 Level 1 (0 points)

    I still don't understand why the motherboard is fine enough for an external display, but not for the internal one. I suppose that external displays have their own power supply ?

  • mrbofus Level 1 Level 1 (5 points)

    Jah_Daffodil wrote:

     

    I still don't understand why the motherboard is fine enough for an external display, but not for the internal one. I suppose that external displays have their own power supply ?

     

    It's not a power supply issue.  The logic board routes the video from the graphics card to the internal display.  If the LCD isn't the problem and the graphics card isn't the problem, then the logic board is the problem.

  • Jah_Daffodil Level 1 Level 1 (0 points)

    If the power supply does not deliver enough power, the internal screen may go off. That would explain why reducing the brightness (and the power needs) or switching to low consumption RAM (or an external self alimented screen) would do the job for some time. My iMac goes black randomly, but also when I connect an USB device...

     

    but surely it may as well be the logic board. Who knows...

     

    When you connect a thunderbolt screen, the iMac boots directly on it ? You don't have any settings to do ?

     

    A.

  • mrbofus Level 1 Level 1 (5 points)

    Jah_Daffodil wrote:

     

    If the power supply does not deliver enough power, the internal screen may go off. That would explain why reducing the brightness (and the power needs) or switching to low consumption RAM (or an external self alimented screen) would do the job for some time. My iMac goes black randomly, but also when I connect an USB device...

     

    but surely it may as well be the logic board. Who knows...

     

    When you connect a thunderbolt screen, the iMac boots directly on it ? You don't have any settings to do ?

     

    A.

     

    Correct; with an external monitor connected via Thunderbolt, when the iMac is powered on, the external display shows an image while the iMac's internal display remains off.

  • wchi100 Level 1 Level 1 (0 points)

    Sounds like it's a video card problem.

     

    Rather than replacing the whole logic board, try with replacing a new video card.

     

    You might be able to save the old one by reflow the card by backing them in oven (400F for 10min).

     

    Good luck

  • mrbofus Level 1 Level 1 (5 points)

    wchi100 wrote:

     

    Sounds like it's a video card problem.

     

    Rather than replacing the whole logic board, try with replacing a new video card.

     

    You might be able to save the old one by reflow the card by backing them in oven (400F for 10min).

     

    Good luck

     

    It's not a video card problem, it's a logic board problem.  The LCD is connected to the video card through the logic board. 

  • aboofhead Level 1 Level 1 (0 points)

    correct but if the video card is faulty then the screen will be black,

    it is easy to diagnose by using the internal led's.

    1 = power connected

    2 = power at the logicboard

    3 = logicboard and grapics card GPU are communicating

    4 = lcd detected

  • mrbofus Level 1 Level 1 (5 points)

    I'm not sure what else to say; the Apple Store had it for two days, looked at it, and said the issue was the logic board, not the graphics card or the LCD.

  • aboofhead Level 1 Level 1 (0 points)

    Ok for no cost to yourself.

    Lay the mac on a flat surface and keep it this way power off.

    just remove the front glass, then 6 X screws from the lcd.

    Lift the lcd out without disconnecting any cables and sit it onto of the mac 40mm above where it normally sits.

    DO BE CAREFUL NOT TO LIFT TO HIGH AS THE CABLES ARE STILL CONNECTED UNDER SIDE.

    look on I fix it for a tutorial with pics.

    You can then power on and check the led status to tell you where the mac is at.

    What is the serial number on your mac?

    I can try get a few pics to show you how to remove the screen.

  • mrbofus Level 1 Level 1 (5 points)

    aboofhead wrote:

     

    Ok for no cost to yourself.

    Lay the mac on a flat surface and keep it this way power off.

    just remove the front glass, then 6 X screws from the lcd.

    Lift the lcd out without disconnecting any cables and sit it onto of the mac 40mm above where it normally sits.

    DO BE CAREFUL NOT TO LIFT TO HIGH AS THE CABLES ARE STILL CONNECTED UNDER SIDE.

    look on I fix it for a tutorial with pics.

    You can then power on and check the led status to tell you where the mac is at.

    What is the serial number on your mac?

    I can try get a few pics to show you how to remove the screen.

     

    I don't have the iMac anymore (sold it for parts) so I can't test it.