imac 2010 Black Screen, External Display working

[perth2000]

Hi,

I bought a mid 2010 iMac off a guy.

It's a somewhat nice machine (27", i7, 8GB RAM and 2TB HD)

The internal screen is not working, I thought I could fix it.



I did these symptom checks:

- On startup I can hear the chime

- Brightness settings are ok

- Reset SMC done

- External display works fine, can use machine normally

- took out display and reseated all the cables

- Only 3 of 4 system check LEDs are on. They turn on 1,2,3 and then nothing. However the 3rd LED seems located right next to the Memory slots, and I am not sure where the 4th LED is.

- I shined a bright flashlight on the screen. I could not see anything, totally black



At this point I suspected the display to be dead.

So I bought a used but working 2010 27 inch lcd (with the same numbers) of ebay.

The seller seemed genuiine and told me the lcd works, it is just slightly dimmer on 1 side.

So I got that LCD today, installed it and still: Nothing.


I cannot run AHD because I cannot see the promts on the external screen.

Does somebody have an idea what else I could do?

And- Can I run AHD when the internal screen is not working?


Kind regards,

Volker





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[perth2000]

so, i coming back from the Apple store.

They ran some tests and it came out as:

- no fans detected

- no sensors detected.


Possible motherboard fail.

they are now ripping the thing apart and give me a quote.