#1 Asus G750JX, MB: G750JW, Rev.: 2.1 No video after short circuit on 3V LDO
da matic • 14 ottobre 2019, 08:37
Hello!
I'm working on gaming laptop Asus G750JX-T4074H with motherboard ASUSTeK G750JW, Rev.: 2.1.
Initial issue:
Completely dead, the chip PU810 was hot (short circuit to ground on 3V LDO output).
The cause of short circuit was KBC chip as usual. KBC chip (IT8585E) replaced with brand new one.
After connecting power supply to the board the KBC chip automatically programmed, keyboard and screen backlight turns on, but no content on the screen.
It turned out that the "Thunderbolt controller" U1101 (DSL3310) is also damaged (short circuit to ground on coil L1301) and its power supply controller U1302 (RT8068A) was bad as well.
Current issue:
After replacing both mentioned components U1101 and U1302 the issue is exactly the same as before:
After connecting power supply to the board, the laptop automatically turns on, keyboard and screen backlight turns on, but no content on the screen. The CPU, GPU, PCH chips gets normally warm. The CPU fan is spinning, but the GPU fan is standing.
If I press on the power button the laptop turns off and won't turn on again (except if I disconnect the power supply + RTC battery - after that the laptop starts automatically after connecting the power supply to the board).
What I have done up to now:
BIOS + KBC chip reflashed with a few different dumps - no changes.
Checked the resistances to ground on all coils - all seems okay.
I believe that the "Thunderbolt controller" U1101 and power supply chip U1302 (RT8068A) was initially bad, but I didn't noticed that at the beginning.
I'm working on gaming laptop Asus G750JX-T4074H with motherboard ASUSTeK G750JW, Rev.: 2.1.
Initial issue:
Completely dead, the chip PU810 was hot (short circuit to ground on 3V LDO output).
The cause of short circuit was KBC chip as usual. KBC chip (IT8585E) replaced with brand new one.
After connecting power supply to the board the KBC chip automatically programmed, keyboard and screen backlight turns on, but no content on the screen.
It turned out that the "Thunderbolt controller" U1101 (DSL3310) is also damaged (short circuit to ground on coil L1301) and its power supply controller U1302 (RT8068A) was bad as well.
Current issue:
After replacing both mentioned components U1101 and U1302 the issue is exactly the same as before:
After connecting power supply to the board, the laptop automatically turns on, keyboard and screen backlight turns on, but no content on the screen. The CPU, GPU, PCH chips gets normally warm. The CPU fan is spinning, but the GPU fan is standing.
If I press on the power button the laptop turns off and won't turn on again (except if I disconnect the power supply + RTC battery - after that the laptop starts automatically after connecting the power supply to the board).
What I have done up to now:
BIOS + KBC chip reflashed with a few different dumps - no changes.
Checked the resistances to ground on all coils - all seems okay.
I believe that the "Thunderbolt controller" U1101 and power supply chip U1302 (RT8068A) was initially bad, but I didn't noticed that at the beginning.
