White Macbook mid-09 screen won't stay on

I turned on my macbook the other day and I got the usual white/grey screen but then before the apple logo appeared the screen turned off.

I managed to get it working several times since by hooking it up to my external monitor and messing around with detect displays and removing the mini-DVI cable. So I could use my laptop as a laptop. But now the Macbook's monitor won't turn on, it's as if the computer is in clamshell mode.

Upon boot the screen may or may not light and if it does it's on for just a second. Then darkness. It's not the brightness, the screen isn't on.

I can plug in my external monitor and coax that into working and sometimes when I disconnect it and open and close the macbook the screen'll come on for a second! but then it's off again. It'll come back on, again briefly, if I have my external monitor on mirror mode and adjust the brightness there, but otherwise it's a no-go.

I'm thinking something's dead or close to it. I hope you helpful lot here can tell me otherwise.

Don't have applecare or anything either so, whoop-di-doo if it is broken!

EDIT:

I'm using the computer right now to type this with my external monitor, so it is functioning other than the screen.

iDutchman said:

Try a PRAM Reset at bootup.

cmnd+alt+P+R. De Mac with reboot itself when you press this keys at bootup.

Click to expand...

Thanks for the response and sorry for the wait.

I've tried this and the screen came on but only for a short while during boot. The usual white screen appeared but the backlight turns off. I waited a while after the boot-up so it could get to the log-in screen and I typed my password hit enter and then turned up the brightness.

Now it seems to be okay-ish. The screen still turns off when I turn it on and if the brightness is cranked up past a certain level. Also on some occasions the light turns off when the monitor is tilted or moved to a certain angle.

logana said:

Likely to be the cable that connects the logic board to the inverter - it is wrapped around the left screen hinge and has been known to break internally (the screen turning off when you move the lid points to this).

Could also be the inverter, the backlight on the screen or worst-case a fault on the logic board.

I would start with the short cable first - they are fairly cheap and not too bad to replace....

Click to expand...

Thanks for the response, Logana.

So it could be a multitude of things.. Where could I get a replacement cable if needs be? I don't live near any outlets to buy anything from, nor any Apple stores to take my computer to for a look at.

logana said:

Whereabouts are you - Scottish Highlands ???

This is what the inverter to motherboard cable looks like

http://eshop.macsales.com/item/Apple/9228281/

Click to expand...

Yes, Scottish Highlands.

Sorry for the late responses, the macbook is currently the only computer i have access to which explains my sporadic posting.

As for the inverter cable, it seems an awfully great deal to replace... and I don't know if I'm comfortable poking around inside this machine, is it worth taking it to an apple store in the future instead? But I'm out of warranty so I'm guessing they'd charge an arm and a leg even for as cheap a fix as this.