Apple Thunderbolt Display backlight works on minimum brightness only
27” Thunderbolt display. LCD element works. The LED backlight, not so much. With brightness turned all the way down, a picture is faintly visible. Turn the brightness up, and the backlight cuts out. It’s kind of like a 3-way lightbulb (remember those?), on which only the lowest-wattage setting works. This started a couple weeks ago, intermittently at first, then all the time. Monitor wasn’t bumped or relocated when it failed, so I doubt it’s a loose connection.
Tried a different laptop (another 2015 MBP), same result. On disassembly, the backlight cable didn’t seem loose; I reseated it anyway, to no effect. Verified 24.0V on the nose at the test point with a digital voltmeter. Built-in cable has some cracking and fraying around the Thunderbolt plug, but same happens with a separate Thunderbolt cable plugged into the auxilliary Thunderbolt port.
I’m guessing that either the backlight part of the screen element has failed, or that it’s a logic board problem. Any way to tell what it might be? Thank you for your suggestions!
Questa è una buona domanda?