PowerBook G4 12" A1104 video output trouble

Hello Mac Help forums! I'm a windows/LINUX user who has never really played around with Macs much (aside from much beloved iPhone/iPads). I recently saw a Craigslist ad offering a Power Book G4 and Power Mac G4 that wouldn't boot properly and figured I might as well try fixing them up. Long story short, I was able to fix the tower but have had trouble with the laptop, which is far neater in my opinion. I'd like to get it working and would be willing to do whatever/buy new components, barring anything really expensive.

Anyway, here's my situation and what I've tried so far. Remember, I'm a complete newbie to Apple computers, so if I don't mention some simple fix, I probably don't know about it.

The laptop in question is a PowerBook G4 Aluminum 12", model number A1104. It has a new battery which holds a charge and works well. It has 1gb of RAM in it, and an Apple Airport Extreme card. When I plug the battery charger in, the light on the charging cable turns green. When I press the power button, I hear the chime sound and the hard drive/fan turn on and the screen flashes black. It flashes a few times as it goes through the boot up cycle, and aside from having no video whatsoever it seems to be working. It ends up on a greyish white screen - again, nothing on the screen but the backlight is on. The apple on the back is alight the entire time, as well. Pressing the "eject" key also does not seem to work (there is a disk in the drive).

I've done a little bit of searching and tried a few things. I tried holding "R" during boot-up. I tried a software reset of the PMU. I tried zapping the PRAM (Though I honestly don't know what that means) by holding down Command+Option+P+R until the chime sounded 3 times. I tried holding down Command+Option+A+V during bootup, because I saw somewhere that that worked for someone, but no luck. I'm planning on trying connecting it to an external display, but I don't have the adapter, though I ordered one on Amazon that should be here sometime next week.

So any advice on what to do next? I already have a newer laptop and tablet, but I really like the form and feel of this little guy, and it'd be neat to get it to work. I was considering opening the case up and making sure all the cable connections were sound, but I'd rather rule everything else out beforehand, just in case. I'd consider taking it to an Apple store, but they probably don't support these anymore, do they?

Well, there's my wall of text. If anyone has any questions or ideas on how to fix this, let me know and I'd be very appreciative. Thanks!

eyoungren said:

It could be a number of things, but usually the big three are this. Either the LVDS cable (the data cable from the logicboard to the screen), the display itself or the logicboard.

You can rule out the logicboard if you have video on an external monitor after boot and it looks fine. Replacing the LVDS cable is a difficult task, so I would suggest just replacing the screen. Most likely it's the screen, it usually is when you get nothing but white.

When you boot the Mac attached to an external monitor you should see an FKey that has a graphic of two windows on the keyboard. This is a built-in monitor switcher key. Right now the Mac is running the main LCD. Push that button and your display will automatically switch to the external monitor. Not knowing this is likely to give you a lot of frustration because the only other way to switch monitors is after logging in. And of course you can't see!

As for replacing the screen. It's a job. You can find the guide on ifixit.com, but just keep in mind that you are basically gutting the machine in order to replace the screen. I bought my wife's 12" 1Ghz Mac and had to do this. It was sold to me with a broken screen (which I knew about) so I bought a replacement screen off eBay at the same time I bought her Mac (got that of eBay too). Most PowerBook screens are pretty cheap on eBay. Just make sure you are getting the entire unit and not solely the LCD itself.

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Hey, thanks for the response! I finally got a mini-DVI to VGA adapter, and plugged it into my external monitor. Unfortunately, I'm thinking there must be a problem with the logic board. Here's what happens:

When I go to boot the PowerBook G4, it makes the startup noise and a light blue screen displays on my external monitor - no cursor, no apple, no login, just a light blue screen. I've tried booting up in Safe mode (SHIFT), Open Firmware Mode (CMD+CTRL+O+F), and Single User mode, but the same thing happens. After the light blue screen displays for about thirty seconds, there is no more video output.

Any idea what could be going on here? Is this little laptop completely dead, or is there any hope for restoring it?

Thanks!

eyoungren said:

Best guess. The Mac is showing you the attached monitor as a secondary monitor. When you boot a PowerBook with Leopard or below with two monitors, the secondary monitor will show solid blue (sometimes gray then blue). The screen where all the action is (the primary monitor) is the malfunctioning LCD (so you don't see it).

The last setting for the Mac probably did not have a secondary display attached so when it gets to the login screen it blanks the second monitor.

Have you tried pressing the F7 key to switch to the attached monitor?

The fact that you can see a solid blue screen with no artifacts, streaks, lines, missing pixels or anything else wierd proves it's not the logicboard, at least in the case of the video.

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I appreciate the follow-up! I just tried that several times - unfortunately, rapidly pressing F7 during boot-up and holding down F7 were unsuccessful. I tried using an external keyboard to rule out problems with the F7 key, but that was unsuccessful too. Any other ideas by chance?

eyoungren said:

I just went back and read your original post. You mention that there is a disk in the drive? It's probably trying to boot from the disk in which case the keyboard command may be getting ignored.

Try this. Shut down the Mac. Press and hold down the trackpad button and then press the power button (keeping the trackpad button held down). This is a standard Apple instruction that tells the Mac to eject any disk in the drive on boot. If that does not work, attach a mouse to your keyboard and press and hold it down in the same manner as above.

We want to get the disk out of the drive and see if it will boot normally off the hard drive. Most likely then it will recognize the F7 command.

If none of this works then there may be an issue with the logicboard, but it's does not see (to me) to be the video.

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Holding the trackpad button down while booting did in fact eject the disk. Unfortunately, nothing else has changed - it still boots to a blue screen for about 20 seconds before going dark, and F7 doesn't change anything..

Edit: It seems to boot in Open Firmware mode if I hold down O S Ctrl Command. Unfortunately, that won't display on my external monitor. I don't know much about open firmware mode or if this could help. I have a friend who has old OS installation disks for OS X 10.3 and 10.4 and will hopefully be able to try installing one of them soon - I'm worried that the installation won't be displayed on my external monitor though, even of it works...