Asus FX506HM DA0NJMBAH0 - no backlight

[ktmmotocross]

Hello.
Have this Asus FX506HM DA0NJMBAH0 with no backlight. I measured
PCH_BRIGHT - 1.16V
+VIN_BLIGHT - 20V
+3VLCD_CON - 3.5V

is that 1.16V on PCH_BRIGHT too low? but i dont have short on its rail and it come straight from PCH

any hint?


https://www.badcaps.net/forum/troubl...c-or-boardview

[mcplslg123]

1.16V is definitely low.

[ktmmotocross]

1.16V is definitely low.

but it is come right from PCH. only ESD and capacitor on that line. no low resistance/25Kohm/. is that PCH damaged or some sensor or bad bios fw can do this? i see some light sensor for backlight on some laptops, maybe it have some

[ktmmotocross]

disassembled lcd but found only camera and two mic, no ambient light sensor

[mcplslg123]

There are no components inbetween on new gen mb's making them very susceptible to PCH damage. I'll suggest to cut the track for PCH_BRIGHT and apply 2.5V-3.0V directly on edp connector and see if backlit works. After all you cant cure the PCH,so lets try a workaround. Even if it works,you'll loose brigtness control.

[ktmmotocross]

There are no components inbetween on new gen mb's making them very susceptible to PCH damage. I'll suggest to cut the track for PCH_BRIGHT and apply 2.5V-3.0V directly on edp connector and see if backlit works. After all you cant cure the PCH,so lets try a workaround. Even if it works,you'll loose brigtness control.

laptop works normally with this anomaly. i cut wire and bridge it to next pin +3VLCD_CON but nothing changed

[mcplslg123]

Check whether +3VLCD_CON is dropping low after bridging..Best not to bridge with any pins from edp connector and use your dc supply to put voltage(This way you also know the current consumption which may give some clue).

[ktmmotocross]

Check whether +3VLCD_CON is dropping low after bridging..Best not to bridge with any pins from edp connector and use your dc supply to put voltage(This way you also know the current consumption which may give some clue).

first i was injecting with psu, but it not work and was little uncomfort because of thin cable. power consumption was 0.0W, i start to think something bad was happen in that brightness line.i must find some testing 144hz lcd

[ash91]

Well my friend i think your problem is the backlight enable signal (bklt_en) or so you can test it by locate the signal on led connector pin
or on the screen panel there is a test point (which is a small dot ) with bklt_en next to it there shuld be 3v on it
if that is the issu you can bybass it by a jumper from 3 v coil or from the screen it self
also by a jumper from 3v fuse to the bklt_en point on the screen panel
i hope this be useful to you

[ktmmotocross]

Well my friend i think your problem is the backlight enable signal (bklt_en) or so you can test it by locate the signal on led connector pin
or on the screen panel there is a test point (which is a small dot ) with bklt_en next to it there shuld be 3v on it
if that is the issu you can bybass it by a jumper from 3 v coil or from the screen it self
also by a jumper from 3v fuse to the bklt_en point on the screen panel
i hope this be useful to you

i dont know why, but i remove lcd and connect another and it works, i connect original again and it works.

[ash91]

Glad to know that problem sovled,some times it is just do not want to work and some times it works