iMac screen replacement

Client brought in a iMac with a dead backlight. Flashlight test shows OSX icons on the screen, but no backlight.

So we ordered a replacement LM215WF3 screen from PowerbookMedic. Replaced the screen as in this video and it does the same thing - still can see icons, but no backlight.

There's a lot of funky artifacts on the dark screen regardless if power on or off. Did we get a second faulty backlight in our replacement screen, or is there something else we're missing? Is there a separate power supply for the backlight itself? I think we got a damaged replacement.

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Elixir2Asked:
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strungConnect With a Mentor Commented:
Might be the LED board. There is a long thread here with also sorts of things you can try:

https://www.ifixit.com/Answers/View/168324/LCD+Backlight+not+working+%3D+solved
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Elixir2Author Commented:
Thank you! We are going the route of the inverter board replacement now. But the screen I got *was* damaged, so it's going back too. We plan on using the original screen which had no visible damage (except no backlight), and adding a new inverter. Will try to remember to get back here to let you know if that fixed it.
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Davis McCarnOwnerCommented:
The LM215WF3 LCD has a separate LED supply voltage of 39-44v which can be checked on pins 3 and 4 of the 6 pin LED power connector.  If its not there, you have a power supply problem.
The connector is on page 12 of this: http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&cad=rja&uact=8&ved=0CF4QFjAF&url=http%3A%2F%2Fwww.avnet-embedded.eu%2Ffileadmin%2Fuser_upload%2FFiles%2FDisplays_NEW%2FColour_TFT%2FLG_Display%
2FLG_Display_LM215WF3_SLC1.pdf&ei=rzXaVIqbCbiLsQSH3IFw&usg=AFQjCNGXoLFQ6JLHRL7vuD1RSVk4zf9GPA&bvm=bv.85761416,d.cWc

P.S.  With all Mac's, the model (i.e. MB994LL/A) or the EMC # are crucial for troubleshooting.  What is one of those?
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