Comment by pandaman
2 years ago
This could be that you just noticed it? Panasonic plasma cells brightness is controlled by PWM off a 600 Hz carrier (it's even proudly advertised as "600 Hz!" on the TV box and stickers). While the number is quite big and stands out nicely against "240 Hz" advertised as refresh rate for the competing LCD TVs, it did not provide many different brightness levels per pixel (keep in mind that it's divided by 60 Hz or higher frame refresh) so those TVs were running temporal stochastic dithering to create more levels. If you looked closely at a new plasma TV screen it was very noisy with random pixels firing up at high frequency.
The level of noise went up dramatically after the first year. I read that this is part of the panel aging. It hasn't gotten worse since then. My two biggest gripes are high brightness areas don't work on large portions of the screen. A windows file browser is basically unusable.
The heat is probably what will eventually get me to replace it.