Black Screen on cold boot

Hello all,

When booting up, laptop will go from standard grey startup screen to black screen, just when it's about to load the login screen.

- External monitor works.

- In target mode screen works

- If I leave it in target mode overnight, so fans are spinning, laptop gets warm, screen eventually comes back.

So is this backlight problem or motherboard problem? Apple Hardware Test reports everything is just fine?

Macbook Pro 17" A1212, 10.6.8, RadeonX1600

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Sometimes you have to run AHT 2 or 3X in a row for it to find errors (also running when screen is working may not find a problem - if it ain't broke you can't fix it).

If the machine has been dropped or opened there could be a loose connector (one that "looks" good but is not snapped, pushed, locked down as it should). The heating causes expansion which makes contact.

Since the external monitor works your GPU/VGC logic board is not the problem, could be:

  • a failing backlight (backlight is a fluorescent and they work better warm than cold)-
  • failing inverter which works when it gets hot, or, as I said
  • a wonky connector (if the laptop has not been dropped or opened this could be ruled out).

So recheck all the connectors… try shining a light through the back. If you can see the desktop faintly its inverter/backlight replacing the inverter is cheapest, easiest so start there.

If this answer is acceptable please remember to return and mark it.

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@machead3, thanks for the quick response & ideas. External monitor always works, I've run AHT this way when laptop screen is black., also I ran the extended test.

How do I shine a light through the back, do you mean take the lcd screen out of its casing?

Can I test the inverter with a mutlimeter?



You can put a flashlight up to the Apple icon on the reverse of the display while it is still assembled and light will pass through the screen. If it's just a backlight/controller problem you'll see the desktop. If you can't see anything it's probably the LED.


You could test the inverter but I don't have the information you'd need… search here or use Google.


@machead3, laptop screen went black again after boot screen, i.e. it goes from grey boot screen to flicks to black when the login screen should appear.

I shone a torch through back & there is no faint image, its blank. So when you suggested the following

>>If you can't see anything it's probably the LED.

Did you mean LCD?


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