Philips 26PF5321 backlight mod, dim backlight
Arrows indicate direction of voltage for "more dimming" with current controlled by voltage drop across twin R's 2R2 from 5.2V. It should be controlled by remote Brilliance on screen and Light Sensor. But this is a more direct way .  

Monitor voltage on test points 1094, 1040, 1038 if you need help choosing an R value and report back.

Then contrast can be increased on display to adjust black level as full black.

There are better ways, but more complex.