Fixing an imac g4 logic board

[Jon183]

Hi everyone,

I have an Imac g4 17" 256MB 80GB Geforce 4MX

This imac was last powered on 6 months ago according to the seller, it now makes no response to pressing power button at all. Here is what I tried: Replaced PRAM battery, reset PRAM by pressing the button, Hold power for 10 sec and plug back in, plug in and power at same time, resat the ram modules, tested diagnostic solder points and got 3.6V for battery, 12.20V for 12V, got 0.01V for 12VLSP and 5V. PSU was tested with multi-meter using the service manual guide and passed the test. I noticed some white and dry stuff around C241 on the logic board (next to 16 pin power connector) that needed to be rubbed off with alcohol, I replaced that cap.
 

What should I do now? I've tried looking for logic boards but ones from the US seem to charge $100 for shipping alone on ebay.

 

[just.in.time]

That's really strange. Have you tried shorting to power button solder points to see if that will turn it on? If so, may just be a busted power button.

 

[Jon183]

Yes, i tried putting a blob of solder on points 1 to 4 of power connector and points 1 and 3 and 2 and 4, still nothing, 5V appears to be an issue, apple service manual says to replace the logic board but I want to fix it, next i will try and run 5V 1a through the molex with an adjustable power supply I have to see if it will fry anything and then replace the fried component.

 

[tal_glazer]

Hey Jon,

I know it's three years later but...Any luck?

Tal