Apple Thunderbolt Display backlight works on minimum brightness only
crwdns2934249:0crwdne2934249:0:
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!
Apple Thunderbolt Display backlight works on minimum brightness only
crwdns2934249:0crwdne2934249:0:
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!
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!