Please help with iMac G4

[eraser]

Hi all,

I am helping a friend with his iMac G4 and have run into some trouble. It had the stock hard disk which was failing, so I removed it and replaced it with a 250 GB drive. Now that the machine is all re-assembled I can't get it to attempt to boot. I press the power button and get a chime. The Caps Lock key blinks, the screen goes to grey and that's it. I can hear the hard disk spinning up and performing a head-check/alignment.

I have reset the PRAM. The HDD was set to CS/Cable Select just like the stock Apple drive.

Does anyone have any suggestions?

Thanks!

[jongleur]

Was it a stock HDD? Did you repartition the drive in APM and format as HFS+? Insert the install CD/DVD, boot holding down the "C" key, from the Tools/Utilities menu, select DriveUtility and if the new HDD is listed, ensure the partition type is APM, and if not repartition the drive, and click the "Options" button to change the partition map.

[phreakout]

Another thing to keep in mind is that the iMac G4 uses Parallel ATA bus for its internal drives. The drive controller may not have 48-bit LBA (Logical Block Addressing), which allows for partitions to exceed 128 petabytes (128,000,000,000,000,000 bytes). The older standard limited you access to about 137 gigabytes (1,000,000,000 bytes) per partition.

So, in short, make sure the first partition contains at least 128 gigabytes (just to be on the safe side) and what is left over goes in the 2nd partition. If your model iMac G4 supports Mac OS 9.2.2 along side an installation of OS X (and if you plan on doing so that way), make sure the first partition is about 7 or 8 gigabytes in size (for OS 9), install OS 9 on that, about 128 gigabytes on a 2nd partition (for OS X) and whatever is left goes in a 3rd partition. That's how I would deal with a drive that large on a Mac like that. The same applies to any drive larger than your 250 GB capacity.

73s de Phreakout.

[mcdermd]

I was thinking about that last night but I swear that all of the iMac G4s supported large drives along with the 2002 Quicksilvers that came out about the same time. I could quite possibly be entirely wrong, though.

[jongleur]

Yes, the QS2002 was the first PowerMac to support large drives, not the MDD as many sites state, and as far as I know the iMacs-G4s were big drive friendly as well.

[phreakout]

Alright, in that case, it's probably just that the drive needs to be partitioned, formatted and the OS of choice installed. If he's getting a grey screen, then later a disk or folder with a blinking question mark, obviously it needs a valid OS installed. OS X for sure and maybe OS 9, but only if the model supports it.

73s de Phreakout.

[eraser]

Thanks for the info guys. I finally had some time to look at this machine again and I think the DVD drive is bad.

But first ...

If he's getting a grey screen, then later a disk or folder with a blinking question mark, obviously it needs a valid OS installed.

This is what confused me. No blinking question mark, just a grey screen. As discussed I was worried that it was also a hard disk size problem.

I power up the machine and hold down the mouse button to get the optical drive to eject. It ejects and I insert a retail Tiger DVD and it just makes repetitive noises as if it is trying to recognize the media. I guess this means I need to find a new optical drive. What optical drives can be used with an iMac G4? I have a ATA DVD drive laying around here somewhere. Can I just use any old ATA drive and have it work? Do I need to modify the drive door at all for it to fit?

The HDD has been zeroed so there is no partition map and if the optical drive is unresponsive then I guess that explains why it never gets to the blinking question mark.

I am not used to dealing with the iMac G4s and after the experience of taking this thing apart I am not exactly a fan.

[jongleur]

Do you have access to external Firewire CD/DVD drive?

Another way is how I installed 10.4 on my Cube that only had a CD-drive. I put the 10.4 install DVD in my iBook and connected it to the Cube with a firewire cable and booted the iBook into Target Mode. Booted the Cube holding down the option key and from the "Bootable FileSystems" selected the install DVD, and then selected "Disk Utility" from the Tools menu (I think it is the screen straight after choosing language) repartitioned the HDD (as APM) and formatted as HFS+ and then installed 10.4 to that partition.

As long as you have access to another Mac with a DVD drive and firewire you should be able to install to the iMac's HDD. Of course this assumes that there is actually nothing wrong with the HDD or HDD controller of the iMac.

[mcdermd]

I love that trick!

[coius]

Also , if it's USB 1.1 I believe those G4's (non-2.0) were USB bootable. It would be slow, but a CD-ROM (IDE) on a USB adapter and/or USB combined DVD drive should be bootable. it seemed when 2.0 came out, apple removed it. Someone said through the Open-Firmware you could make a G4/G5 boot from USB 2.0. I seem to remember trying this and it did work on an iBook G4, so you might try to figure out how. I had to select the USB device and make it load the bootloader from the disc.

[phreakout]

eraser,

Yes, you can use pretty much any optical drive with parallel ATA to boot that iMac G4. No need for you to mod the drive door mechanisms at all for fitting. CD-ROM only, CD burning only, DVD-ROM, DVD-ROM and CDRW (combo drive) and DVD burning drives (Superdrives) will all work. Some of the more modern DVD burning drives with dual layer burning might work, but make sure you're burning under OS X Panther and later.

The Target Disk Mode trick is indeed a neat one! Any Mac with fire-wire ports on it can attempt this. Simply restart the Mac and immediately hold down the letter T on the keyboard, before the startup tone is heard. A solid blue background with a yellow dancing fire-wire symbol will appear on the screen. All you need now is a fire-wire cable (6-pin male to 6-pin male) and another fire-wire Mac (laptop or desktop). The Mac placed in Target Disk Mode will act as an external drive device. When both Macs are linked together with the fire-wire cable, the TDM Mac's drives will mount up on the second Mac's Finder (works with both hard drives and optical drives); yes, the second Mac you just boot normal. Works wonders when you need to install an OS on a Mac that won't let you from its optical drive being bad or a limitation from the TDM Mac's logic board. USB external drives will also mount as well.

Your hard drive now needs to be partitioned and formatted before installing the OS. First, make a decision if you want to have just one or two OSes installed, say Mac OS 9.2.2, Mac OS X 10.x.x or maybe both. If just OS X, then create 1 partition (The whole drive); if OS 9 and X, then 2 partitions ( I usually set the OS 9 partition at around 8 gigabytes and whatever larger portion for OS X). You can use Disk Utility off of the OS X Install disk to do all this preparation before installing.

NOTE: Some iMac G4s wouldn't allow you to boot and/or install OS 9 from startup; you can only use OS 9 in Classic Mode under OS X. You can use the Target Disk Mode trick to get OS 9 onto that iMac; just make sure the second Mac can boot to OS 9 natively, meaning at startup.

I know all this sounds obvious, but I'm listing this for our novices, beginners and n00bs out there.

73s de Phreakout.

[eraser]

UPDATE!

Okay. I got Tiger installed using Target Disk Mode. The machine boots ... but no video.

I can hear the Tiger intro music so I know the machine is booting. The LCD lights up and is gray but there is no video at all. I noticed that while I was running it in Target Disk Mode that there was no Firewire logo but the drive showed up on the PowerMac I was using to build the machine so I went along with it.

I have re-opened the bottom of the machine and verified that the LCD connector is indeed inserted where it should be. I have reset the PMMU.

I don't have a mini-VGA connector to try an external monitor. What else should I try? Any suggestions?

[jongleur]

Depending on your viewing angle and lighting, can you see any faint image on the iMac's LCD screen? It could be that back-light for the screen that is either disconnected or otherwise not connected to our shared reality.

[eraser]

The backlight is working properly. The screen lights up normally but remains a light gray with no image. (It is the same shade of gray that usually appears with the Apple logo.)

[phreakout]

eraser,

Can you get into Open Firmware? (Cmd + Option + letter O + letter F) If you can see text on the screen afterwards, then the graphics are rendering machine level text fine. From here, I would try resetting the nvram:

1.) Type in "reset-nvram" and press Enter
2.) Type in "set-defaults" and press Enter
3.) Type in "reset-all" and press Enter

If the iMac comes back with some text while completing step 1 or 2, simply repeat those steps until the iMac's responses don't appear. After step 3, the iMac should restart.

If you're still getting the same symptoms, then there is something wrong with the hard drive or something got corrupted during or after installing OS X. Try this:

1.) Shutdown your iMac.
2.) Press and hold down Shift key while powering on; this will place you into Safe mode.
3.) Wait awhile. The iMac should be checking the hard drive.

If you still have the same symptoms, I would:

- Restart the iMac and place it in Target Disk mode (hold down letter T before startup tone is heard)
- Reconnect iMac to another Mac using a Firewire cable
- On the second Mac, run Disk Utility. Verify and repair the iMac's hard drive along with fixing it's permissions as well.
- Afterwards, restart the iMac and reboot.

If still getting the same problem, check the PRAM battery. Make sure it is showing 3.67 volts or higher. If not, then replace battery. If still no luck, it may be the built-in graphics on the iMac's main logic board. Replace with a known good exact match logic board.

73s de Phreakout.