Compaq X1000 no Backlight

[PowerIC]

Hi,

I Have a Compaq X1000 motherboard that works fine on external monitor, but on internal LCD there is no Backlight.

Tested with another vga card and lcd and problem remains.

On an simple diagnose, with a working motherboard, measured capacitors C78 and C79 as per picture and there is 3V on left side and 0V on right side.

On the failing motherboard, the C78 as the 3V and C79 as 0V on both sides.

Replaced the C79 capacitor and same problem.

Any idea on how to start searching ?

Thanks

[masud]

ur MB works fine with external monitor means other then the LCD portion are fine. ur LCD might be faulty. there is a tube inside the LCD, try to find and replace.

thank you.
K.M.Masud.

[PowerIC]

Hello !

Thanks for your repply.
The lcd lamp is ok, the motherboard circuit responsable for the ccfl tube power is bad.
Tested all components on other MB and are all ok.
There is some failure on MB power circuit.

Thanks