This Philips has a unique backlight with more than 200 LEDs in a tight matrix. I generally like the high-end Philipses from the early 2010s. The good panels, decent sound, and ambilight on three sides make them attractive products. The seller mentioned random stripes when started cold and after warm-up the device worked ok.
When I fired it up, the image I got made me go "ah, crap, panel fault or backlight broken".
Not so quick! This backlight is capable of sharp local dimming! So, the mainboard was producing information and the dimming reacted to it. After a while the patterns changed fundamentally:
Now, I was pretty convinced that the TCON board was to blame. When pixels are at the wrong place and there is no constant pattern, the TCON is the go-to board.
After a search in the Iwenzo repair forum, where I am active, it appeared to be a standard fault with this model. The X200 resonator is faulty. Not quite broken, but mechanically instable. The exact name is C25M000000S001. I bought it from Farnell's branch develektro.com, which is for private customers. Farnell only accepts business customers.
With a preheater plate and hot air, the replacement is a matter of seconds without stressing the board.
The problem here is that the resonator is specified for 70°. It gets roasted by the chip and after a number of years, it is going to give up.
And here were are:
The backlight has a minor problem caused by aging, however. In some situations, blocks of LEDs shine through slightly. This is also a known issue and the reason is the warped plane that carries the LEDs. They get a little too close to the diffusor foil. I'll fix that later, as I need to take apart the panel for this.
I ruined the moth-eye screen surface. To remove some fingerprints I used a soft microfiber cloth and a mild glass cleaner. That left a grey residue on the surface. After researching a little, the original Philips cleaning liquid is "alcohol-based". So, I put some Isopropanol on the cloth and wiped it again. That did even more damage.
Philips does not want you to clean the screen! They only supplied a small special cloth with a cleaner to remove single prints. The previous owner just dusted it off and never touched it.
I was able to get rid of the grey smear with Armor All and meticulous polishing. It is pitch black again, but it has none of the anti-glare properties anymore.