Help! Had I just purchased an used Thunderbolt Display with a broken screen?

[timidhermit]

I just purchased an used Thunderbolt Display off Facebook Marketplace. The display passed basic testing I did during the meet-up. The original owner claimed that the display never had any issue (a claim which I am now questioning).

A couple of days into using the display, a cluster of pixels at the bottom left corner of the screen became "faded" in color. Re-tested the display using PassMark MonitorText. The pixels are not dead or stuck, but the color (particularly blue) looks off or faded. I intially thought that this is backlight bleeding, but I am not so sure anymore. I did a burn-in test. No change to those pixels. However, yesterday, the same cluster of pixels looked less "faded" so that the color appeared to be coming back (though still not totally normal). I have no idea why this is happening. Searched through Reddit, MacRumors, and elsewhere and found no answer. Today, the same screen area looks a tad worse than yesterday but is not as bad as a couple of days ago.

Can someone please explain to me why this is happening? Did I get scammed into buying a dud Thunderbolt display?

 

[frou]

I don't know the physical makeup of the Thunderbolt Display, but it's possible that some layer inside the sandwich is becoming delaminated. This has manifested in various 5K Displays as the "pink edges" problem.

 

[Fishrrman]

"Can someone please explain to me why this is happening? Did I get scammed into buying a dud Thunderbolt display?"

Such are the hazards of buying used equipment, especially older equipment.

My advice:
Go forth from this day... and learn... a sadder, but wiser, man.

 

[Bigwaff]

Thunderbolt display over 10 years old. If all work, not a dud. Maybe heat related? On TBD, the glass is held on by magnets. You can pull glass off and blow out dust that has accumulated over the years.

 

[timidhermit]

Thunderbolt display over 10 years old. If all work, not a dud. Maybe heat related? On TBD, the glass is held on by magnets. You can pull glass off and blow out dust that has accumulated over the years.

Interesting idea, Bigwaff. Is it possible that some dust is interfering with the pixel elements at the corner of the screen of my display? I just watched a several videos showing the dissembly process of this display. One video warned that more dust might get added once you removed the glass overlying the panel to try to clear out dust from one part of the panel, akin to the problem of putting a screen protector onto a phone or tablet.