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My mid-2009 MacBook Pro just had a high speed meeting with my floor. (I thought those magsafe cables were supposed to disconnect when you tripped over them... sigh)

Now I get strange glitches and flickers on my screen. Strangely, these occur only at high brightness settings. They start to show up when I'm three brightness levels away from the maximum.

Another apple.SE question suggests that the glitches could either be due to a short circuit on the display cable, or a defective inverter board.

Is one of those two issues at play here? Which one? More generally, what's my problem and how do I fix it?

I'm not covered by applecare, so, if possible, I'd prefer to do the repair myself.

Glitches& flickers

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I wouldn't imagine an inverter board would be relevant here, its sole purpose is to control power flow to the backlight. If the screen flickered black or the brightness seemed to flicker then you might look at the inverter board but I highly doubt it could cause graphic anomalies similar to yours.

Your examples look more video related, which would point to either the logic board, LVDS (display) cable and/or LCD panel itself. You can narrow it down using the following diagnostic steps...

  • Take a screenshot (commandshift3), do the video anomalies appear in the resulting screenshot picture? If so then it's likely a failure with the video card/logic board or possibly RAM. If not then it's possibly the LVDS cable and/or LCD panel.
  • Connect your Mac to an external display, do the video anomalies appear on the external display? If so then it's likely a failure with the video card/logic board. If not then it's possibly the LVDS cable and/or LCD panel.
  • Does the issue change at all when the display is tilted forward/backward? If so then it's likely a loose or damaged LVDS cable and/or LCD panel. I should specify, the LCD itself is probably ok but it's built in controller board could be damaged. They ARE replaceable but it's likely a lot easier to replace the LCD itself, though thats still quite a task with the unibody MacBook Pros.
  • Remove and re-seat the RAM (iFixit has a handy guide), does the issue persist? If so then I would doubt, but not rule out, that RAM is the culprit.
  • Run Apple Hardware Test (Insert the gray "Disc 2" that came with your Mac and hold D while powering on) and note any failures.
  • Try re-seating the LVDS (display data) cable as shown in step 8 of iFixits display guide.

Hopefully that helps and at least points you in the right direction, good luck!

  • 1
    Wow, great answer. Thanks! I'll try some of these out and post the results. – dB' Oct 29 '13 at 14:58

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