Asus S510U not power on after liquid damage (Mainboard X510UNR REV 3.0)

Good morning friends of the forum. This laptop is brought to me in the laboratory and they tell me that it has dropped water, plugging in the power supply gives no sign of life. Disassembling I find several oxidized spots behind the motherboard. I clean the whole board with isopropyl, rebuild some broken tracks and finally when I connect the power supply the power on led lights up but I have no image. I tried to reprogram the bios, reprogram the kbc, replace the ram but nothing to do. The absorption is 0.17A. I made some measurements:

PL8901 0,84V
PL8701 5,14V
PL8702 3,33V
PL9301 0,09V
PL9103 0,90V
PL9101 0,90V
PL8102 0V
PL8101 0V
PL8103 0V
PL8302 1,03V
PL8601 1,22V

Hello.

robgerr ha scritto:I clean the whole board with isopropyl, rebuild some broken tracks

Did you replaced all corroded components?

robgerr ha scritto:The absorption is 0.17A

Something on the board should be warm with this power consumption. Check, if smaller core of CPU is getting hot. Is fan spinning when it's connected to mainboard?
Measure resistance to ground on the coils.

Hi xamledyD

I cleaned the board by removing the oxide, I re-soldered the components such as resistors and capacitors, I removed the qfn involved, re-soldered the pads and re-soldered the qfn
The pch integrated in the cpu does not heat, the core of the cpu does not heat, nor does the gpu heat up, instead they heat up a little the coils that feed the gpu.
Fan not spin

Coil Resistance:
PL8901 10 Mohm
PL8701 4Kohm
PL8702 14,7 Kohm
PL9301 1Kohm
PL9103 20 ohm
PL9101 20 ohm
PL8102 4,80ohm
PL8101 6,70ohm
PL8103 4,60ohm
PL8302 39 ohm
PL8601 115 ohm

Please, post a clear photo of spilled area of the board in current condition.

Photo pre-clean:








Photo after clean and repair track and resoldered qfn :

Replace all corroded components regardless of whether, if they seems functional or not.

cleaned up the board and replaced several components but not all of them because I didn't have them, I redid the pads and resoldered the components. There are no absorption, the 3V and 5V converter works because I find the voltages in the coils but I no longer have the power LED and it no longer absorbs 0.17A

What is an actual current consumption of the board (in mA) before and after pressing to the power button?

the absorption is so low that the bench power supply does not mark it, however using the multimeter in the amperometer I measure 0.0050A

Measure the voltages to ground on pins 3, 6, 7, 9, 12, 13, 17, 20 of chip PU8701.
Measure the voltages to ground on pins 1, 3, 4, 5, 6, 11, 12, 24, 25, 28 of chip PU8900.

PU8701
PIN 3 3,30V
PIN 6 3,27V
PIN 7 3,36V
PIN 9 8,3V
PIN 12 19,1V
PIN 13 5,16V
PIN 17 10V
PIN 20 3,26V

PU8900:
PIN 1 19,1V
PIN 3 18,58V
PIN 4 24,309V
PIN 5 5,98V
PIN 6 2,60V
PIN 11 3,29V
PIN 12 3,29V
PIN 24 6V
PIN 25 5,87V
PIN 28 18,88V

Measure the voltage to ground on pin 1 of jumpers JRST2401, JRST2402.

JRST2401 pin 1 3,18V
JRST2402 pin 1 3,18V

Measure the voltages to ground on pins 4, 12, 14, 35, 57, 67, 70, 74, 77, 85, 86, 87, 88, 96, 109, 111, 112, 127 of KBC chip.

Measure the voltages to ground on pins 56, 110 of KBC chip in the following cases:
a) Power button released.
b) Power button pressed.

KBC:
PIN 4 0V
PIN 12 1,85V
PIN 14 3,29V
PIN 35 0,48V
PIN 57 0V
PIN 67 0,70V
PIN 70 3,36V
PIN 74 3,29V
PIN 77 3,26V
PIN 85 3,26V
PIN 86 2,27V
PIN 87 3,29V
PIN 88 3,29
PIN 96 0V
PIN 109 3,29V
PIN 111 3,29V
PIN 127 3,29V

PIN 56 2,45V after press power button stay AT 2,45V
PIN 110 3,30v after press power button voltage drop to 2,36V,after release power button go to 3,30V

robgerr ha scritto:PIN 110 3,30v after press power button voltage drop to 2,36V,after release power button go to 3,30V

The keyboard was spilled and it is probably damaged.
Disconnect the keyboard and try to turn on the machine with bridging pins 5 and 6 of keyboard connector J3101.

If the machine does not turn on, remeasure the voltages to ground on pins 56, 110 of KBC chip in the following cases:
a) Pins 5, 6 of keyboard connector opened.
b) Pins 5, 6 of keyboard connector bridged.

Measure the voltages to ground on pins 1, 3, 5, 7, 8, 14 of chip PU8803.

on pin 56 there was something strange sometimes I found a voltage of 2.52 V now for example it remains stationary at 0.60V if I jumper pin 5 6 of the keyboard connector always remains at 0.60V.
On pin 110 I find the voltage 3.30V, jumper pin 5 and 6 and it drops to 0V
PU8803:
PIN 1 3,29V
PIN 3 3,29V
PIN 5 2,97V
PIN 7 3,40v
PIN 8 3,40v
PIN 14 3,29v

The keyboard is definitely damaged.

Was the board also spilled under the APU hybrid?

no matic, I no found traces of oxide near the hybrid

The communication between the KBC and PCH part of the APU hybrid is missing.

Try to reflash the KBC chip with programmer.
If it does not change anything, the try to replace the KBC chip.