iMac motherboard problem

[Zotaccian]

I have 2006 iMac which has faulty motherboard, all other components have been verified to be working.

The problem is that the machine does not boot, it does power up when pressing the power button, hard disk spins and optical drive makes the usual sounds it should. However, fans do not spin, they both make one small rapid movement but do not spin. Also if I connect a USB device, like my backlight keyboard I have, the backlight will blink quickly , every time. The machine will stay in this braindead state until I power it down. Heatsink gets warm.

I know that these models suffer from GPU defect (ATI X1600) and I have already sent this to guy technician for reballing which should be done now but above symptoms were present before this reballing.

He now sugges that I sent the board back and he'll reball the Intel chipset as (according to him) it controls pretty much everything on the motherboard, includin fans. I would like to ask if anyone here has had these same kind of symptoms and managed to get the board fixed? Also all types of suggestions whether or not it could be a chipset problem or not are welcomed. There are no bad caps visible, most of the are solid caps.

 

[MiniMoke]

Same symptoms here, harddisk becoming corrupt after some hours use and no more able to boot. After a diskrepair allbackto normal for just somehours.

I changed the mainboard (got one on ebay....) and the machine's up and running strong again.

Btw, the local Apple authorized reseller wanted to charge about 600 Euros for swapping the board - I paid 89 with postage

 

[Zotaccian]

So the fans on your machine were not spinning and there was no power to USB devices (except a brief spike) ? Because I cannot boot the machine at all no picture etc. but hard disk and optical drive do spin up.

 

[MiniMoke]

My disk was spinning up and I got the grey startup screen ,sometime with the APPLE,sometimes not and then the machine just hung.

Try to start from optical drive and use DiskUtil to try a repair. Worked for me, but the disk became corrupt again.

I guess only hope is a change of Logic board

 

[Zotaccian]

Yeah, well with this one it's much worse. I eventually got the fans running by detaching power cable and then pressing the button for couple seconds before plugging in the cable (button still pressed) and then I did let go off the button and after that when I pressed power button fans were spinning at maximum speed. No chime or anything but atleast it seems that there's nothing wrong with the fans, they all can get power.

I also own a small Android -tablet which can be recharged via USB and it seems that the machine is able to charge it when powered, no matter in which state, no fans or fans at maximum.

Logic boards on eBay are ridicously priced, atleast those which sellers agree to send here. I'm not sure if this can be fixed but maybe I just send it back to that repairer, atleast in the beginning he said that if he cannot get it fixed he'll only charge 30-40 dollars for trying. For this another time I send it to him I only need to pay postages.