01-16-2011, 02:10 AM

I have a Black Macbook (2.4Ghz model). The back light has been turning off. If I leave the brightness all the way down for a few minutes then turn it up 1 notch the display will work for about 30 minutes before the back light goes off again. But if I put it any higher then the first level of brightness then the back light goes off even quicker. But sometimes the backlight will stay on for hours. So with all that being said, Is this a display issue or an inverter issue? Any help would be great!! Thank anyone in advance for helping.

01-16-2011, 02:18 AM

Most of the time, those kinds of issues are caused by the inverter. The inverter is a step-up transformer that increases voltage from the battery to power the CCFL tube backlight. Those CCFL tubes rarely go bad in my experience, and are usually rated for tens of thousands of hours. The inverters, on the other hand, do have a tendency to fail - which is why I'm glad that most of the industry is moving onto LED backlighting.

Replacing an inverter is usually pretty simple stuff. I have not done it in a Mac, but typically it involves removing the display, removing the bezel around the screen and popping out a tiny circuit board that is held in with just a couple of screws and has two wiring harnesses running into it. For most laptops, it's a 30 minute job - less if you're mechanically inclined.

You should be able to get the details, parts, tools and model-specific instructions here:

FixIt.com | Fix It | it solutions | it business

(and I'm not affiliated with them in any way, aside from being a customer).

01-16-2011, 02:24 AM

Thank you. Thats what I was thinking as well. I just wanted to get some more input. Yeah I looked at the walk thru that was on that site and it doesn't seem too bad. I am gonna try the inverter first just because it is WAY cheaper. But I will post if that cures the issue

01-16-2011, 02:29 AM

Originally Posted by stocsux

Thank you. Thats what I was thinking as well. I just wanted to get some more input. Yeah I looked at the walk thru that was on that site and it doesn't seem too bad. I am gonna try the inverter first just because it is WAY cheaper. But I will post if that cures the issue

In my opinion, it's almost certainly the inverter. Only one other part would cause that kind of a problem (assuming the system board is in good shape), and that would be the LCD flex cable that leads from the system board to the display. But that's pretty rare as well.

I've replaced dozens of these in my time, on just about every make of computer out there, and I've only ever misdiagnosed it once - and that was on an Alienware machine. That particular model actually had a known issue with the systemboard that tripped up a lot of techs like me. Unfortunately, I didn't catch it until I had replaced the inverter, CCFL tube and eventually the entire display (which ended up being at my own cost, since I couldn't justify charging the customer for my own failed diagnosis). Ah well, live and learn...

Fortunately in your case, this seems like a pretty cut and dry situation - and I think I've read a post or two here about failed inverters on that particular model. So, it wouldn't be like it's unprecedented.