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Model A1311 / Mid 2011 / 2.5 & 2.7 GHz Core i5 or 2.8 GHz Core i7 Processor

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iMac No Display, no 4th diagnostic led

HI,

could someone tell me where I can find pinout for espower pwb-iv49151t inverter board please ?

I need to test it as I've just receive replacement screen for my iMac and it's still dead.

symptoms :

-4th diagnostic led not on.

-when dp ribbon disconnected the fans go full blast.

-when all the cables are connected the internal screen is discovered as online by system info and starts with internal as main screen (4th led still off).

-when disconnected from inverter board screen is not discovered.

the Mac works fine with external display.

if anyone have any suggestions I'll be forever grateful.

Seb

Answered! View the answer I have this problem too

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Ok, so after bit more testing it turned out that the problem was onboard DP connector, all working as intended now.

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So, I have an imac 5k that has no backlight. Did you just change the lvds cable? Or did you have to solder? Thanks!

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sorry for the delay, it's probably too late now but to answer your question, it was a soldering job I'm afraid.

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LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or LED driver board might be installed incorrectly or need replacement.

iMac Intel 21.5" EMC 2428 LED Driver Board Replacement

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I know all that, I've service manual for this model, the 4th led is NOT illuminated and before I splash out on new inverter board I'd like to find a way of diagnosing it, eg test the pinouts.

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Sebastian Nastarowicz will be eternally grateful.
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