Well, sadly after a very deceptive and unsupportive experience with the NEC helpdesk for Spain (seemingly shared with France and Italy) limited to reiterate the "copy-paste" answer I posted previously; I contacted the SpectraView workshop in Germany and they (more politely) said it´s "a major panel error we only can solve by swap of the lcd module", but due "that LCD2490WUXI² is end of life and not produced anymore. There are no lcd modules left so we can´t offer any repair of your unit".
They gave no further information about the nature nor origin of the issue, any measure to prevent or ameliorate it, any repair solution or any guarantee that the issue will not happen with newer models.
So my feeling is that I am left in the void, with two supposedly high grade (expensive) monitors with just 10.000-11.000 hrs (just out of warranty) marginally suitable for image editing work. My impressions are that:
- Or NEC has a planned obsolescence policy in order their products just survive their 3 years warranty, or these models suffer from defects due inadequate fabrication or quality of components expected in a serious professional product.
- The NEC technical service has very limited agility and capacity and an overall lack of helping support, and their customer management policy limits/cuts any tech information about the problems their products have.
Then, facing the perspective of buying two new monitors I, sadly again, have to say that they will hardly be NECs again due to lack of confidence in their professional quality-life expectancy and worthlessness of their Technical Service for problems out of standards.
I´ll probably check other professional brands with 5 years of warranty (EIZO) that at last are better investments due to longer assured working life... or (assuming LCD technology has intrinsic problems) the opposite option of buying relatively cheap monitors that you can change without any remorse.
Anyway I'm still interested in knowing more about that weird issue and in if it's caused by
- Some form of ionization of the LCD TFT panel (following what the Beharware site says about the "type II mura" they describe).
- Thermic induced deformation of the diffuser or polarizing layers or their in-between interface (glue?), causing refractive interlayer problems or semi transparency due to slight changes in polarization orientation.