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Repair Imac G5 logic board with faulty capacitors.

jean at huens dot be    20110626

Problem detection

The  Imac G5 did power on but nothing did appear on screen, no startup sounds neither.

Use http://support.apple.com/kb/TS2094 to diagnose the problem.
(put the imac face down on a soft surface).
The diagnosis will be to replace the logic board, but currently there are none available  from  Apple  and on Ebay its rather costly.

Repair it yourself

Since the Imac is open, look at the capacitors, some upsides are bloated or even do leak.

Before  removing the logic board its easiest to remove the devices, disk, DVD, memory, cooling plastics.
These devices are fastened with brass screws.
This is procedure is explained on the apple support site.
I find it a good idea to make some notes and tag the connectors during diassembly, it eases the build later on.

The logic board is fastened with blank metal screws, you need a torx 2 and 1.5 mm screwdriver.

On the underside of the logic board there is one IC covered with termal paste (=white blob). Remove the paste
and do not forget to apply new paste before replacement.

And finally you are ready for soldering:
On my board there were 21 faulty capacitors, all 1800 μF, 6.3 Volt. Some of the faulty one were below 100μF.

Soldering is not easy, you need a good,hot soldering iron, I got the help of a friendly HAM amateur (thanks).

After replacing the capacitors one can reassemble the Imac, donot forget the thermal grease :

At this stage I did the first test and it worked...