Black screen Packard Bell EasyNote LM86-JU-004BE

[Johnny Berben]

Black screen Packard Bell EasyNote LM86-JU-004BE

CPU = P6100
Chipset= HM55
VGA = ATI Mobility Radeon HD 5650
Origineel LCD = B173RW01-V3 17.3inch 1600x900 WXGA++ Glossy Wide(LED)

On original internal screen = black screen. (backlight ok)
On external screen get image and works normal.

Changed LCD cable, still the same, black screen on internal (backlight ok), image on external screen.
Tested internal screen in another laptop (ACER Aspire 7250). Screen is 100% OK!!

Then tested laptop with 15,6" screen (N156B6-L0B) and i got normal image on laptop!!
Then tested again with the original internal screen and get black screen and image on external. (backlight ok)

Then tested with 17.3" LP173WD1 (TL)(A1) and got scrambled image with vertical stripes (backlight ok), and external got image.
Then tested with 17.3" N173FGE-L23 and got black screen on internal (Backlight OK) and external got image.

From servcice manual PB EN LM86 the 17,3 screens that i tested must working in this laptop.


So wath would be the problem?
The 17,3" screens that i used to test works 100% in another laptop.
With my EN LM86 only backlight and no image (black screen) exept with the LP173WD1(TL)(A1), here i got scrambled image.
But a 15,6 inch screen works normal.
External works normal.

Where i need to start seeking fault for this strange problem?

Thx in advance

[polytek]

Re: Black screen Packard Bell EasyNote LM86-JU-004BE

hi bro,
first you need to check the lcd drive power if stable with the two lcd module, pin 2 and pin 3 of the lvds con mesure should be taken on the lcd con not on the motherboard, then you need minimum of 3.0 volt to work with B173RW01-V3 if for example voltage is 2.9 volt the input signal goes to high impedance (means no data displayed on the screen) only the backlight work because it's separate.
see page 13-14-18 for lvds drive logic and lvds work condition and lvds connexion.