Chosen Solution

Hi, First of all, I have to thanks the all community on Ifixit. So many Topics helped me so much. Now I guess it is my time to ask you guys some help, please. My iMac (VM831NV60KM) suddenly stopped working while I was using it. Now, it’s rebooting in loop with black light, chime, fan but no keyboard recognized . LED Diagnostic showed 4 LED lights are working. all ON, I mean. I’m wondering if the problem can be the CPU, Logic Board, or power supply? CPU and power supply should work if the all 4 LED lights are on, isn’t? So it’s the Logic Board? Thanks for your help. cheers Jim

Apple iMac 24-Inch “Core 2 Duo” 3.06 (Early 2008) Specs Identifiers: Early 2008 - MB398LL/A - iMac8,1 - A1225 - 2211 This is a very unusual case. I would first try the keyboard in all the USB slots. I would be inclined to go for the power supply first. These things can partially fail and supply power to things and not others. Pull it and look for bad capacitors (cans). This was a major issue about the time your machine was produced. Bad caps may have swollen tops and/or show leakage. UPDATE 5/26/20 If I remember correctly, this machine came with system installation DVDs. Please insert the install DVD, hold down the C key and boot from it and tell us your results.

hi , i doubt it is the CPU , they are rare to go faulty but logic board -Yes if not light at all after 5 min , all the best

Hi @mayer

I checked all usb nothing worked.

i checked the power supply but I have no idea of what is good or wrong so here some pictures

one place looks darker… like I said I don’t know if it’s normal or not.

then when I remove the thin cable, the “thermal paste” ? Had a crack but still in place.

Aslo I just remember, before the imac crashed, days before I had the screen turning black for few seconds or even minutes…while i was working with.

thanks @mayer

The logic board is even more fine

i mean nothing looking bad noticeable. So yes like I said. Before the iMac crashed. I had the screen turning black for no reason. Sometime secs sometime minutes. I don’t know if that can help

Hi everyone, @mayer,

any ideas ? motherboard, power supply ? thanks