Powermac G4 Boots up but with Black screen?

Cassie, welcome to Apple Discussions.

Here's the info from the service manual.

Screen is black, but startup chime is present, drive operates, fan is running,
and power LED is lit
1. Check video cable/card connections and connector pins.
2. Test with a known-good monitor. Replace the monitor, if necessary.
3. Remove all third-party devices.
4. Reseat the video card.
5. Clear parameter RAM. Hold down Command-Option-P-R during startup until you hear
a second startup chime.
6. Reset the logic board. Refer to “Resetting the PMU on the Logic Board” in this
chapter.
7. Replace the video card.
8. Replace the logic board.

Screen is black, there is no startup chime, and drive does not operate, but fan
is running and power LED is lit
1. Check video cable/card connections and connector pins.
2. Reset the logic board:
3. Refer to “Resetting the PMU on the Logic Board” in this chapter.
4. Reseat the video card.
5. Reseat the processor module.
6. Replace the processor module.
7. Replace the logic board.

Resetting Cuda/PMU on Power Mac G5, Power Mac G4, Power Macintosh G3
http://docs.info.apple.com/article.html?artnum=86760

Power Mac G4 (AGP Graphics/Gigabit Ethernet): Resetting the PMU on the Logic Board
http://docs.info.apple.com/article.html?artnum=95037

 Cheers, Tom 😉

I seem to be having a similar problem. I just reinstalled OSX as a last ditch attempt heard the intro video but still the screen is black.

I'm using a fairly new video card (ATI Radeon 9800 Pro Mac Edition) Only thing is have to use the $100 dollar dvi adapter for the old 23 inch display. I have to unplug the computer shut down my battery backup supply and restart the whole thing. Then it sometimes comes up?? I'm still trying to trouble shoot it.

Hardware test comes up fine video card should be ok. I have noddaclue.

Quicksilver is very close to the scrapyard 😟

Hey, funny enough, I have the same problem going on. It's a real doozy!!! My setup is as follows:
- 2001 PowerPC G4 Quicksilver (733mhz originally), overclocked to 800Mhz
- upgraded to 1.5gb Ram
- 40gb Maxtor HD (Startup Disk) and a 500gb Seagate HD
- upgraded Nvidia Geforce 7800GS (flashed and working for mac)
- NEC USB 2.0 PCI card
- M-Audio Revolution 5.1 Audio card
- Edimax 801.11n wireless internet adapter
- DVD+-RW
-Mac OS X 10.5.8

I've been using this setup for close to a year if not longer and haven't had any problems. Last night, i was running low on my startup disk (1.5gb available) and decided to try and install a 3rd HD to the same cable my DVD writer is on. It's an original Mac HD that came installed in the Quicksilver. After I installed the HD (turned off computer and opened up and so on and so forth) and tried to reboot. Computer would start up, fans running, hd/dvd drives working, but got a black screen. And I can't get passed it!!! I've removed the HD and reboot, still nothing. I've reset the PRAM and still nothing. I've checked all over Mac's Discussion pages and tried all the advice and still end up at a black screen. I've taken the PRAM battery out and tested it and my battery tester says its low/somewhat close-to-dead. Tomorrow I'm going to buy a new PRAM battery and hopefully that fixes everything. My question is though, if it isn't the PRAM battery, what is it? What could the HD that I tried installing could have done to my computer?Video? Maybe when i tried reseting the PRAM before, i messed up along the way and could have pressed it more than once consecutively, causing it to crash??? if thats the case, how do i fix this???? any help would be great. I'm going INSANE with this problem!!!

Message was edited by: Irectus

I should add that I'm using a dual display. 1x15'' Samsung SyncMaster 570V TFT and a ViewSonic Graphics Series GS790. Everything was working perfectly fine until yesterday when the 3rd HD went in.

Message was edited by: Irectus

Oh yeah, and I've tried starting the machine up from cd/dvd, but I can't even get to a screen. Just stays black. I've also tried starting in: Single User mode doens't work, safe mode doesn't work, target disk mode doesn't work, force startup doens't work, none of the keyboard shortcuts work on startup.

I think I've read that 5 or 6 times now. That doesn't help. Has to be Processor or or Logic Board then. How does a hard drive do this to a computer?!?! Guess I'm just going to have to spring on a new Mac Pro, Stay ahead of the game for a while.

Hi-

Try removing all old hard drives, and install just one, empty drive.
Then, see if you can boot to the OS X install disc.
An overly full boot drive can muck all kind of things up, to the point of failure to boot.

BTW, your OS X install disc must be 10.4.6 or later, or it will not boot with the 7800GS installed.

If your OS version is earlier, I would swap out the 7800GS for the OEM card and try again.

Hey, thanks for the reply japmac. Will try the hard drive swap now. I should update you and say I've bought a new pram battery and that didn't fix it. And I'm booting off mac 10.5.1 at least DVD. I haven't tried popping in the g4's original hardware cd's and all, maybe I should try that? I just figured seeing as it can't boot from the mac os x DVD, it won't see the cd. Anyway, thanks again. Anything else would be greatly helpful.

Didn't work. I'm really beginning to think it's the Logic Board. I'm not too sure if the hard drive is completely functional at startup (I have tried other HD's though), along with the dvd drive. I initially hear a noise, but then can't distinguish between the cpu/fan. The light on the front of the tower is on though and there is a boot-up tone. Is it possible that when i tried installing that drive (the 1 in my original post), and it was possibly formatted under Windows XP although I'm pretty sure Mac os 9 or X, shot my IDE/ATA connectors/cable on/attaching to my logic board? That's the only possible explanation....

I also don't know if you guys figured it out on your own, but in order to boot from mac leopard, you need to open firmware and "trick the computer" with that whole process. I've done that a couple times now and maybe messed with the whole firmware on the G4??!? If thats the case, how do i get the computer to recognize an input signal; from keyboard/monitors/any internal drives, etc. I'd try the hardware cd's but the computer won't recognize them i'd assume just like the mac install DVD.....

Ok, i've read somewhere that my problem is probably a low-level hardware problem.... what does that mean and how do i fix it?