11 
7 
2 Black Screen - No Display - External Display OK
I have a Mid 2012 MBP 13" 2.9 Ghz i7 here that is baffling us...
It chimes and that is it - No Display, just stays black.
The GPU was fine as it only went in for a backlight fuse repair.
WE CAN RULE OUT the following as they have been tested on other units:
Screen / LCD cable / SSD / RAM / Keyboard / Touch pad & Battery are all good.
The backlight fuse is new and OK & display voltages are also OK.
External display is OK. Just nothing displays on the units screen.
SMC & PRAM have been reset multiple times in testing.
Upon booting we have a chime and that's it, after some time if you press any key it will flash the screen indicating that the backlight is OK. But nothing else The LCD connector is clean and shows no sign of wear or corrosion and also gives voltage readings. Are there any other voltage lines that we need to check that maybe have been missed upon to check or can anyone point us to what they personally would check from the start for voltages regarding displaying graphics? @oldturkey03 Any suggestions? What line is responsible for the display working from the connector backwards?
Similar to this issue Display Shows Backlight but No Image
Bu iyi bir soru mu?
FYI - The 13” only has the Intel Iris graphics engine. If you clean off the thermal paste inspect the smaller of the two chips that’s the I/O and graphics services. Often I find the chip is fractured.
Dan tarafından
@danj Isn't the Iris Engine only on Retina displays? But OK, will check for any damage under the micheal scope tomorrow. I did replace the paste previously and all was working well until it had a backlight issue, we fixed that, worked for a few days then we are with no display.....
livfe tarafından
@livfe - Review EveryMac as different series used different solutions. The 2010 and older 13” used a combo GPU-I/O chip solution both AMD and NVIDIA were used. The early 2011 was the first to use the Iris engine in the 13”.
Dan tarafından
@danj OK to clarify this is regarding a 2012 A1278 2.9 i7
livfe tarafından
@livfe - Here’s that exact system: 2012 13” 2.9GHz i7 MacBook Pro jump down to Video Card: there you’ll find Intel’s Iris HD Graphics 4000 listed.
Dan tarafından
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