8440p no display on internal screen

[RethoricalCheese]

HP 8440p which does not display on internal screen at all but is able to boot to Windows.

I tried VGA output, doesn't show anything either but atleast I can hear VGA cable connect and disconnect sounds.
Tried DisplayPort - got a display.

Where should I look for the problem?

Just in case updated BIOS to latest but like expected, it did not help.

[OKRPKCOMP]

Re: 8440p no display on internal screen

same prob here also
Somebody help pls

[OKRPKCOMP]

Re: 8440p no display on internal screen

Where r the all tigers of badcaps???
Too many persons face this problem in hp 8440p (KCLOO LA-4902P REV 1.0)
i have changed the bios, screen and procesor, but problem is same
Motherboard turn on and windows runs fine on external display but there is no display on internal screen
where i should look to solve this prob????

[mon2]

Re: 8440p no display on internal screen

1) See attached.

2) Confirm there is no damage to the LCD connector / interface cabling for the display panel.

3) Meter in DC volts mode (30v or higher is ok). Carefully measure the voltage on each pin while using the INTERNAL display.

This review should answer:

a) is the LCD being powered ?

b) is the LCD display ENABLED ?

c) is the inverter / backlight voltage present ?

d) intensity of the backlight is driven by INV_PWM.