iMac G4 Optical Drive Replacement & Autopsy

Vision problems.

As I noted in my review of the iMac G4, the optical drive was not working. Essentially what occurs was the drive would try to read a disk for about 30 seconds and then spit it back out. This can be one of two things, one is that the lens may be dirty and needs cleaning; this can be done with some specialized products. The other is that the drive may have just flat out shit the bed for some undiagnosable reason. Because the replacement I found wasn't much more expensive than a drive cleaning kit, I decided to do the extra labor for something that's guaranteed to work; plus I get to see the inside of the thing finally. Lets get started!

I'm just going to say right off the bat that working on the G4 isn't as daunting as it may seem. Just because it wears the Apple badge doesn't totally mean "fuck you" to anybody trying to do some home repairs or upgrades. The G4 pretty much looks like an old computer on the inside but with a lot of things made to proprietary standards to fit inside the weird dome base. For starters you need tools; a Phillips screwdriver plus Torx T15, T10, T9 drivers is all you need along with some means of safely discharging static, you know, just in case.

First thing you want to do is remove the cover plate on the bottom of the base. Unplug everything and lay the G4 screen down on safe surface. Unscrew the four Phillips screws: they won't fall out. Use the screws to pull the cover plate off the G4.

Underneath the plate you will find the AirPort Wi-Fi card and the RAM upgrade slot. This varies between G4 models and some may or may not have these already installed. Older G4 models running the 700-800 MHz processor will have the older AirPort card but this shouldn't change anything significantly.

Pull the AirPort card out of it's slot and then disconnect the small wire hooked up to it. This thing is super stubborn so use a screwdriver for leverage or gently pull it out with pliers. The RAM card is much easier: push out on the silver tabs on the sides of the RAM slot. The card pops up and be pulled out.

Being that those components were really the only parts of the G4 Apple intended on being easily user accessible, you will have to bust out your Torx T15 driver for the next step. If you don't have one, bad luck unless you have some sort of crazy DIY method of removing these god-forsaken things without a proper tool. Removing the four screws here is honestly pretty satisfying.

Once you remove the screws, gently pull the lower part of the dome straight off, don't twist it. Set it down and take a moment to examine the proprietary chaos inside the G4. Like I said, a lot of it is just familiar old computer parts set up in way to suit this case.

The motherboard is easily the most oddball thing in here. Obviously it's not ATX standard; very far from it. The whole thing is round and it only has one RAM slot holding a 256 MB stick of DDR RAM. The naff and terribly obsolete 1.25 GHz PowerPC G4 processor lies under the gold heatsink, presumably soldered directly to the motherboard. What I believe is the modem card is the green board above the rest. There are two ATA slots for the drives and one Molex to power them both.

In the upper half you find the drive rack which holds both the optical drive and a standard 3.5" hard drive; an 80GB IDE 7200 RPM Seagate. Next to the drive is the built in speaker and behind it is the power supply. The PSU is interesting because it's split into two halves, one on each side of the dome: this is for the hard drive to fit between them and the single cooling fan to have somewhat of a better passage for airflow.

Anyways the rest of the repair is really easy now that the case is open. Unplug both ATA ribbon cables and the Molex behind it. Only unplug these to make things easy. Again, depending on your model of G4, the motherboard layout might be different but the process is the same.

Using the Torx T9 driver, remove the two screws holding the drive shield in place and pull it off, tape and all. Mine had no screws for some reason so the tape was all that was holding it on and I had to replace it.

With the Torx T10 driver, remove the four screws holding the drive rack in place. Once those are removed, grab both side of the drive rack and gently wiggle it out of the case. This take a little bit of effort and caution as you may accidentally pull wires out.

And that's all there really is to it. Unplug the cables, remove the four screws holding the drive to the rack, swap, and reassemble. This takes about 15 to 30 minutes by my estimate and it really is much easier than you would think. In case you get a Kernel Panic on boot it probably has to do with the RAM being messed with during the disassembly. Boot into safe mode by holding down the shift key until the Apple logo shows up. If the Kernel Panic doesn't happen, reboot like normal and it should clear up. Afterwards I popped in a DVD; the drive revved up and played it with no problems. It feels kind of nice making a horribly obsolete piece of technology a little more useful.