ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

[Techbuddy2020]

I don't have a schematic and board view so I take pictures to the power supplies that are not switching.

Unit is with power but no Display.

Main power rail = 19V
Main Bios Pin8 = 3.3V
Power button = 3.3V
No Voltage in RAM= I suppose that supply I label #2 with Voltage In 19V - No Drain Voltage

Label #1 (see image) - with Voltage In 19V - No Drain Voltage

Already checked all the mosfet but its not shorted It seems that they are not switching at all. I think the Driver of those mosfets are Faulty can anyone confirmed. Your input here would be a great help! Thank you!

[Techbuddy2020]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

I also wanted to inject supply to see what is heating up but I do not know where to inject and how much voltage needed.

[Techbuddy2020]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

I check again the laptop and found out that there are 3 more supply that are not Switching so Total of 5 supply that are not working.

Charging Light always On even without battery.
Steady Power LED Light after pressing power button.
Only 19V found in the LCD/LED Connector no other voltage

Could it be the SIO Chip is Faulty?
SIO- ene KB9026Q C

Please anyone could give me an idea. What would be the possible issue on this laptop. Thank you! Stay safe!

[Techbuddy2020]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

Any input would highly be appreciated! Thank you!

[Techbuddy2020]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

Hi, Update: I checked the Resistance to Ground on coils please see the actual value on the image. Those circle in yellow are not working. Can anyone tell me if the resistance value are good. Thanks and stay safe!

[Techtiger]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

S4(SUSP# SUSON#) S3 State (RUN ON) are missing that’s why no voltage on the coils Resistance is good find out requirements off SIO chip find out the data sheet of SIO ,may be Bad Bios Flash BIOS with a good Bin back up old bin

[Techbuddy2020]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

S4(SUSP# SUSON#) S3 State (RUN ON) are missing that's why no voltage on the coils Resistance is good find out requirements off SIO chip find out the data sheet of SIO ,may be Bad Bios Flash BIOS with a good Bin back up old bin

@techtiger
Already flash the BIOS still the same. Could you please check the data of the SIO in the image versus the Actual Voltage value? Thank you for the input highly appreciated.

[Techtiger]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

check the voltage on the pins 37 84 89 before you press PWRBTW & after press the PWRBTW

[SMDFlea]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

boardview - https://www.badcaps.net/forum/showthread.php?t=85968

[Techbuddy2020]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

check the voltage on the pins 37 84 89 before you press PWRBTW & after press the PWRBTW

Those Pins has 0v before and after press the PWRBTW.

[Techbuddy2020]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

boardview - https://www.badcaps.net/forum/showthread.php?t=85968

@SMDFlea
Thanks

[Techtiger]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

Those Pins has 0v before and after press the PWRBTW.

now you have the Bordview from @SMDFlea test if the SIO get the power are you sure no voltage on those pins ? pin 22 96 125 116

[Techbuddy2020]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

now you have the Bordview from @SMDFlea test if the SIO get the power are you sure no voltage on those pins ? pin 22 96 125 116

Yes, I am sure. About this pins 22 96 125 116 also 0V before and after.

[Techbuddy2020]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

Does it mean that the SIO is Faulty?

[Techtiger]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

Does it mean that the SIO is Faulty?

SIO is not getting power that's why all OV you have to trace it back to 3/5V Regulator with help of the Bordview trace it back, You should have some basic knowledge when you are troubleshooting check PU8701 all inputs & out puts

[mcplslg123]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

Check RTCRST as well.

[Techbuddy2020]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

SIO is not getting power that's why all OV you have to trace it back to 3/5V Regulator with help of the Bordview trace it back, You should have some basic knowledge when you are troubleshooting check PU8701 all inputs & out puts

@techtiger
You might be right this may be the issue. I checked the voltage out few times and some of the pins changed its voltage value (eg. Pin8 & 9) It has voltage at first and after I pulled off the charger and plug it again the voltage becomes 0V. Same thing with Pin 3 & 4 and few other pins.

[Techbuddy2020]

Re: ASUS X442U With Power but No Display, 2 of the Power Supplies are not Switching

Check RTCRST as well.

@mcplslg123
I can't find the RTCRST and I don't see an RTC Batt on this board.