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Screen flickers and turns off, inverter or inverter board?

I know that its likely the inverter or the inverter board, but I was hoping that someone could help me determine which.

My backlight works sometimes - but after a short period it usually goes dark. This can be fixed temporarily by turning the brightness all the way down and then up.

This fix only works sometime, and some jiggling of the screen usually helps if its not working. When it doesn't work, the screen flashes on for a fraction of a second then off immediately after.

I've opened it up, and neither the inverter board or the cable look toasted or worn out really, although I didn't get to see all of the cable.

I'm thinking its the board, as the screen will flicker for a fraction of a second when the brightness is increased from 0 to 1, which to me seems to imply that the cable is ok as if no power was reaching the board it would not flicker at all. Then again, I'm no expert in this.

I've read through most of the other threads, but couldn't find the answer, so sorry if this is a repeat question!

Thanks in advance for all your help, and the sweet guides on this site. Oh and I'm fairly savvy so feel free to ask whatever!

Beantwoord! Bekijk het antwoord Dit probleem heb ik ook

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Ja Nee
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hey matt, im having the same problem you had.

did you find out what the problem was?

i read a lot of threads where people have the same problem and everybody says, that it is the inverter.

so i changed my inverter but it didnt fix the problem.

i probably shouldve checked the inverter first with a multimeter as being suggested here, but i didnt read that anywhere else :(

and i didnt really understand how i should do that, could someone please explain it a bit further?

my display works fine, except for the backlight.

up until a week ago i could still use it and every other hour i had to switch the backlight back to zero and up again.

but now it only works for a split second.

moving the screen up and down did break the backlight in some cases. so it could be a loose contact i guess.

but i dont know where i should check that :-/

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Hello Matt,

did you resolve the problem?

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Due to the age of the machine, along with the flickering you mention and with changing the brightness level sometimes bringing life to the backlight 90% chance the CCFL bulb in the LCD has reached it's lifespan. The other 10% inverter cable or inverter. The CCFL bulb can be replaced, but it is not an easy job. Most people chose to replace the entire LCD. New LCDs for these are available on eBay for about $70USD including shipping.

To test the inverter cable. Preform a continuity test using an analog multimeter/multitester (One with the needle.) while moving the wires around. Do this for each wire in the cable. If the needle sweeps hard at any point, it is a break in the wire and the cable needs replaced. Digital multimeters usually have to slow of a reaction time for this type of test and/or have circuitry in them to ignore quick fluctuations in a reading.

One way to test the inverter, if you have a multimeter that can measure frequencies of 50k or more, take a piece of paper and use it as an air gap between the probes and run it along the lower bezel if you get a measurement of around 30k towards the center your inverter is good. Inverters are cheap enough to buy one to swap out to be sure it is not the problem.

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Ja Nee
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Thanks for your response. I hope its not eh CCFL bulb, but you could certainly be right. My screen was replaced early 2009 with an eBay replacement, would this make a difference?

I'll get a multimeter to check the cable and inverter board today hopefully and get back with the results. Thanks again!

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If you can still see the desktop when the screen goes off then you most likely have inverter or inter cable problems. If the screen is black you probably have LCD issues. Move the screen up and down to determine if you have cable problems.

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Ja Nee
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Still can see the desktop - not an LCD problem I dont think. And sometimes moving the screen turns it off, sometimes it doesn't - but it seems more like the inverter is getting overloaded or something - screen won't stay on if the brightness is turned up very much. Jiggling the inverter cable when its on doesn't make it flicker or turn off either. So maybe the board?

Would the board becoming overheated potentially be a problem? How could I test which it is?

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pls try this link. http://support.apple.com/kb/HT3964

give a feed back after

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Ja Nee
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Thanks, but I've already tried both the SMC reset and PRAM a few times, no luck.

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Matt zal eeuwig dankbaar zijn.
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