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MC Gatty
Sep 8, 2007, 11:31 AM
Hello all. The official mac forums haven't helped me out yet, so hopefully someone here can help me out... I would appreciate it very much!

Some background: my dad bought a 12.1 aluminum PowerBook, 1.5 gHz, for use at work. One day, he left his bag unattended, came back, and the display was no longer operational (gasp!). We can only assume someone knocked it or dropped it or something. This was nice for me, however, as it works perfectly with an external monitor (I'm using it right now). Recently, I decided it'd be fantastic to have a laptop of my own (he's since gotten a shiny new MacBook), but I have a few questions floating around.

1. Is it really necessary to take the whole computer apart to pull out the LCD?
2. If I were to buy a dead-logic-board 867 mHz model, could I use its screen in my computer?
3. Assuming I can, would it be lesser quality as compared to the 1.5 gHz version's screen?

Thank you all VERY much in advance.



mkrishnan
Sep 8, 2007, 11:46 AM
Does the backlight even turn on? You know, if there's no evidence of physical trauma to the LCD (i.e. you can see that the glass shattered -- this is typically visible with the backlight on at minimum, and you can almost always tell immediately) or to the computer (some dents it didn't have before), I would not be so quick to assume that you have a broken LCD.

I'd actually look at one of these things first:

It's fairly rare that a drop or fall would take out not only the LCD but also the backlight and/or inverter. Normally the screen should light up but have a distorted image. If this is not what you're seeing, then I would therefore immediately suspect the backlight, the inverter, the cabling, and possibly lastly the reed switch.

- The inverter provides AC power to the CCFL -- it's actually a fairly common failure point on notebooks. If it fails, there should be no light to the screen at all.

- The CCFL backlight itself could certainly also break from trauma or just have burnt out.

- The cabling in the hinge, etc, can be vulnerable, either to pinching or damage in the middle of the cable, or to simply being unplugged on one end or the other.

- The reed switch works in conjunction with a magnet (near the trackpad in this powerbook, I think) to tell if the mac is open or closed. If the computer is behaving normally lid open (aside from the screen), this isn't the issue; if it is only working lid closed, though (goes to sleep immediately with lid open and no external display), then the reed switch might also be the culprit.

Anyway, I would rule those things out before you go and get a new LCD...usually when the LCD is broken through trauma, you know right away for sure that this is the issue, rather than just having a mysterious screen failure.

MC Gatty
Sep 8, 2007, 02:12 PM
It's fairly rare that a drop or fall would take out not only the LCD but also the backlight and/or inverter. Normally the screen should light up but have a distorted image. If this is not what you're seeing, then I would therefore immediately suspect the backlight, the inverter, the cabling, and possibly lastly the reed switch.
The screen does not light up at all. I also can't see any activity on the screen whatsoever; I had read somewhere else that you can see faint images if it's just the backlight. However...

- The inverter provides AC power to the CCFL -- it's actually a fairly common failure point on notebooks. If it fails, there should be no light to the screen at all.
- The CCFL backlight itself could certainly also break from trauma or just have burnt out.
...these are definitely possible. Should I be able to see anything on the screen if it's just the backlight? I've tried looking at the screen under various lightings, hunting for images, but with no success.

Thank you for possibly saving me from a costly mistake. If I may ask another small favor... do you have any recommendations for guides to diagnosing my problem (or are you charitable enough to write up a bit)? I haven't poked around inside it much, so I wouldn't recognize a bad backlight or inverter. Luckily I can already rule out the reed switch (it works fine open and closed), but otherwise it looks like I'm going to be doing some exploratory surgery - especially if it might just be unplugged!

MC Gatty
Sep 12, 2007, 07:20 PM
Bump.

(Any further info is greatly appreciated! I daren't get inside my laptop without at least a little more to go on...)

mkrishnan
Sep 12, 2007, 07:40 PM
Mmmm, I'm sorry, I know that those are the common failure points. If you can't see after trying carefully to see stuff on the screen though, then that does seem to suggest that both the backlight and the inverter (which just powers the backlight, and not the LCD, as far as I know), are not responsible. So hmm... cabling?

MC Gatty
Sep 12, 2007, 08:08 PM
That's what I was *thinking*, but like I said - I didn't want to proceed without a little more info. Thank you, and wish me luck...

dacreativeguy
Sep 13, 2007, 01:00 AM
Turn on the computer and shine a light through the Apple on the back of the screen. If you can see something, then only the backlight is dead.