Apple powerbook. Screen is Blank / very dim, but.....

[mah300274]

Hi. I have been having issues with this laptop for a while now. I bought it to fix it up but am not able to so far. It is a powerbook g4 and I have replaced the bottom case, 2 new chargers, battery, cd drive, extra ram, and the screen is now giving me issues. I never have had the screen work fully so I am not sure about anything.

The screen appears very faint / dark. And now my story....

--I bought an inverter and that did not fix my problem so then I went to buy a ccfl bulb (same kind) and that did nothing (actually I could not even get the ccfl bulb to light up for some reason, I did have to resolder but all the joints were fine...). I gave up with that and bought a new screen.

--With the new screen it sounds like the same issue, very dark.

I am thinking like before when I said the bulb would not light up, what could prevent that? Is there something on the mobo cause I do not think its the screen anymore.

Any help is Thanked!!

[Rik from RCE]

Have you tried connecting it to an external monitor to see if you get the see symptom?

F1 and F2 should control the screen brightness! Have you tried them?

[mah300274]

Yes I have done an external monitor and that works fine. The f1 and f2 does not do anything (that would be funny tho if I forgot the brightness keys $150 later...).

[Rik from RCE]

If F1 and F2 do nothing then perhaps the keyboard is faulty?!?

[mah300274]

No, it works fine. And I tested the voltages to see if anything was going to the plug to the ccfl bulb, one is reading I think it was 2v and the other was 1vish?

[Rik from RCE]

That does seem rather low. I will have a look in the workshop to see if I have one lying around to test the voltages on.

[mah300274]

I might be able to test again if that is to low, because I was just looking around. But if its low what can I do? I have $300 into it and I would like to sell it soon. But this is just strange.... Any ideas you want me to try?

[Rik from RCE]

I'm thinking you may have a motherboard fault. Problem is, replacing it is gonna be very expensive indeed! DO NOT try testing the output voltage of the inverter. It could ruin your DVM and give you a very painful shock.
I have a colleague who knows a lot more about Mac's than I do. I will have a word with him and see what he says.

[mah300274]

ok. Thanks.

[Rik from RCE]

Have spoken to him, he says if it's not a faulty keyboard then it's a faulty motherboard.

[mah300274]

Faulty mainboard just to lite the ccfl bulb? Everything else works, I was even on it for a while on the external screen. Anything you think I can do?

[jingda]

Try going to the apple link
http://www.apple.com/support/powerbook/

What version are you using. If a powerbook is the same as a macbook maybe i can help you. Reasemble the parts again follow the instructions in the apple guide book. be more specific in your problem. Like whether the powerbook freeze during startup or you see a flashing question mark sign or the screen is dark but it is not in sleep mode

[mah300274]

version of software?

Are you talking about all of this?
Make sure that the power cord is plugged into a working wall outlet, and that it's properly connected to the power adapter. To check that the wall socket is working, plug in a lamp or other electrical device.
Make sure that the power adapter is properly connected to the power port on the back of the Mac.
If your Mac is a portable, check that the brightness of the built-in display is not set to "0."
Reset the Mac's parameter RAM.
On an iBook or PowerBook, reset the computer's PMU. For an Intel-based Mac, reset the SMC.
If video is available remove display-related preferences:

Delete the com.apple.windowserver.plist preferences located at /Library/Preferences/com.apple.windowserver.plist and ~/Library/Preferences/ByHost/com.apple.windowserver.xxxx.plist/
There may be multiple com.apple.windowserver.xxxx.plist files in the ByHost folder. The xxxx will show as a series of letters and numbers. Delete them all.
Once the preferences are removed, reset the PRAM

[jingda]

You are starting to confuse me. You said that your powerbook light is very dim but can it still login and use?

[mah300274]

Yes.

[jingda]

have you try changing the battery your battery might be a bit old

[mah300274]

I have bought a new battery (1 cycle on it so far) and basically a new everything else.

[jingda]

What do you mean by that. Is your problem solved or the lights are still very dim?

[mah300274]

I mean what I have been saying.... Everything but the board has been replaced at this point and the screen is dim.....

[jingda]

Then try replacing the motherboard