I'm seeing a symptom I can't explain:
I replaced a faulty LCD (a Quanta QD15AL01 rev.5) in my notebook (a Dell Inspiron 6400) with a "compatible" display (a Chi Mei N154Z1-L01). The new display's backlight does not respond to changes in brightness correctly:
The brightness can be set from 1 to 8, which should be dimmest to brightest. With the new display, the dependence is not monotonic: 4 appears brightest, followed by 8, then 1. 2, 3, 5, 6, and 7 are fairly dim, but show some variation. Even 4 does not appear to be full brightness. The pattern is perfectly repeatable and stable as I change the brightness setting.
I've tried two different inverters, including the original inverter. Both inverters work fine with two other displays I've tried, but both exhibit the same symptom with this display, so I attribute it to the backlight responding incorrectly to the output of the inverter, rather than it being a fault with the inverter. This seems strange, though, since the backlight is a relatively simple CCFL, I think.
Is it possible that this particular backlight is reflecting power into the inverter in a funny way that causes the inverter to malfunction for certain dimming settings?
Is it possible that the inverter is doing PWM and giving the backlight frequencies it doesn't like for some dimming settings?
Is there any communication from the inverter back to the graphics card/motherboard, such that it could be telling the software something confusing about the display? I thought the connection from the motherboard to the inverter was just an input, with power and dimming signals.
I am convinced that this is not a software problem, as the symptom persists while in the BIOS screen, and is unique to this display, which does appear to be otherwise compatible with the computer.
Thanks much for any advice.