iMac Blues

My iMac G5 was purchased as a refurb from Apple, and it was a good thing that I bought the 3-year extended service plan. Almost immediately it had to be worked on; the Superdrive was refusing to read/write DVDs. Some time later, the computer died, and the power supply had to be replaced. Finally, just before the 3 years was up, it died again, and once again, the power supply was replaced. A few months ago (back last Fall), it suffered a hard drive crash, and I installed a new hard drive.

We've had a number of brief power outages, and several weeks ago I called home and the phone rang continuously; the fax modem did not pick up. Sure enough, when I got in, the iMac was dark. Following SOP, I tried a restart. After the chime, the Apple came up, and then suddenly the machine shut down. I tried again. The second time, the desktop picture came up, but there were funny squiggly lines across it, and when I clicked on a widget, the machine crashed. The third startup seemed stable, and the machine ran for several days before it began having problems again.

Diagnostic testing using the diagnostic LEDs seemed to point to the power supply again. I started looking for a replacement on-line. Then I came across a site which described fixing the power supply. It also had instruction for repair of the motherboard.

It seems that Apple, and a number of other manufacturers, in looking for a cheap supply of capacitors, had bought from a Chi-Com manufacturer that had cranked out defective units. The problem is so widespread that there are distributors on-line which sell replacement capacitors specifically to tackle this problem.

I now have the instructions for the fix, and started collecting the necessary tools. Here are some shots of the problem:


Motherboard, showing bulging caps (red marker added by me)


The bulging is evident here and in the next picture


While only 2 caps appear to be damaged, the advice is to replace all 25 of them.

The real problem, probably the cause of the failure of the MOB caps, was in the power supply :


Here you can see that one of the caps is leaking. That is NOT marker on the top of that capacitor; it is capacitor juice. 8 of the 11 are bulging


The scorch marks on the PS cover show how hot this got.

The cost of replacement capacitors is about $60. The cost of a replacement motherboard and power supply is more than the value of the computer (well over $700). I picked up a T-10 Torx security bit today (for opening the "No user serviceable parts inside"), and I'll be getting an 80W soldering iron. One supplier I found sells the caps for about 50 cents each, but you have to order in multiples of 20, and that supplier doesn't carry all the caps for the power supply.

For anybody with a 17", 20", or 24" iMac (Intel versions as well), sooner or later you will need to either replace the power supply or replace its capacitors. I'm curious now whether that was the problem in Maria's G3 Blueberry iMac. When I'm feeling real fixy I'll have to peek inside that one. It would make a nice email machine for Granny.