33 
40 
8 No Backlight - Cannot locate the fault
2015 MBA A1465 (820-00164) - We power up, the screen will 'flash' and then go off, we can see the logo with a flashlight through the apple logo on the case, We have changed the 'P' Fuse, U7701 Backlight I/C & Q7706 MOSFET, Backlight enable is present 8v, We have tested with another display and the same (Ruling out a faulty LCD). All the components we have listed above are holding voltage and are not blowing.... @oldturkey03 any ideas what we need to check next? Technician is baffled. (We haven't tested with an external display as yet but have no reason the GPU has crashed as we do have an image).
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4 commentaires
It sounds like the boost logic has failed. There is a few caps that need to work for the logic to work. Check the caps.
par DanJ
@danj Any idea of the part numbers so we can locate them on the boardview and schematics? I think your right because the technician said I have 8v but it needs to be 24?
par livfe
@livfe - locate the backlight inductor which is located near the LVDS connector, there are two larger tantalum capacitors and one smaller on the other side.
par DanJ
@livfe - Give these Vids a watch How Buck, Boost & Buck-Boost DC-DC Converters Work and How Buck Converters Really Work (and Why Vout = D·Vin)
par DanJ