CATATAN TEKNISI HARDWARE: Asus K55VD - backlight doesn't work

Jumat, 23 Februari 2018

Asus K55VD - backlight doesn't work

I have a problem on the backlight of asus k55vd. The backlight doesn't work all the time (probably because of liquid spill on the power module). Sometimes it's working but it doesn't light up the whole backlight matrix, sometimes it doesn't light up at all. Playing around the power module with a magnet dose the trick, but it's seems it's only temporary, and doesn't always work. Right now it's working and i did some measurements. Legend: Blue -> backlight on; Red -> changed value when the backlight is off

Plate: E89382 HannStar J MV-4 94V-0 rev 3.0. Could not find schematics / electric diagram.

Made the folowing measurements on J4601: 20, 21, 23, 24, 25 according to this topic: (see "lcd" picture).

Here is the pinout of the LCD jumper cable J4601

40
39 GND
38 GND
37 GND
36 GND_AUDIO
35 INTMIC_P
34 GND
33 GND
32 GND
31 USB_PP9_C
30 USB_PN9_C
29 +5V_CAM
28
27
26
25 +LED_VCC_INV
24 +LED_VCC_INV
23 +LED_VCC_INV
22
21 LED_BKLTEN
20 LED_BKLTCTL
19 GND
18 LVDS_LCLKP_PCH
17 LVDS_LCLKN_PCH
16 GND
15 LVDS_L2P_PCH
14 LVDS_L2N_PCH
13 GND
12 LVDS_L1P_PCH
11 LVDS_L1N_PCH
10 GND
9 LVDS_L0P_PCH
8 LVDS_L0N_PCH
7 EDID_DAT_PCH
6 EDID_CLK_PCH
5
4 +3VS_C
3 +3VS_LCD
2 +3VS_LCD
1

Measurements on the power module:
Once I got the same "backlight on" measurements (blue) on the power jumper (J6801) and the LCD backlight was off. So I am not sure where is the problem.