Asus F555U dead

[DeniS182]

Hi,
I have here this dead laptop- no lights, nothing. 19V rail is present, 3.3V is on pwr button, but on bios chip I have only 1V.
+3VSUS = 0V
VSUS ON 2.6V

What is this IC? PU8803

Motherboard: asus x555uj rev 2.0
I attached boardview. Have someone schematic for this model please?

MOD Edit: Boardview - https://www.badcaps.net/forum/showthread.php?t=91136

Thanks for any answer.

[piernov]

Re: Asus F555U dead

What is the resistance to ground on +3VSUS?

[DeniS182]

Re: Asus F555U dead

Resistance to ground is 0.17ohm. But I can't find what is shorted. Nothing hot here.

[jasko_jacker]

Re: Asus F555U dead

PU8803 provide also the voltage to EC if pin 13-14 have low resistance probably there is a problem with EC

[DeniS182]

Re: Asus F555U dead

+3VA_EC is present, there is no short. But I don't know why when I inject 3V from power supply to shorted power rail +3VSUS , power consumption is about 3-4A and there is not hot component. I can't find what is shorted.

[jasko_jacker]

Re: Asus F555U dead

Check the continuity on PU8803 PIN 6 -> 9 if there is not short then the short is on +VSUS line only and probably there is a short inside cpu, You should cut the SL2607 , SL2603 and Jp3301 , one by one and every time you cut (gently not in deph, remove only a small line of copper) measure the resistence again between +VSUS and GND if the short disappear power the motherboard again and check if +VSUS is 3.3V.
Report measurement

[DeniS182]

Re: Asus F555U dead

6 ->9 shorted and when I inject 3V voltage here chipset die was hot.. so my cpu is dead..

[jasko_jacker]

Re: Asus F555U dead

Remove PU8803 check resistance on pin 6 and pin 9
If the short is on pin 6 and no on pin 9 no cpu dead
If the short is on pin 9 and not on pin 6 you should cut
the jumper so know cpu dead (no main power line)
Report measurement

[DeniS182]

Re: Asus F555U dead

I removed PU8803 and short is on both pin 6 and pin 9

[jasko_jacker]

Re: Asus F555U dead

It's very strange, resistance on PU8803 between pin 6 and 9 without component ?

[DeniS182]

Re: Asus F555U dead

0.64ohm

[jasko_jacker]

Re: Asus F555U dead

+3VA_DSW->+3VSUS , it takes the voltage from the pu8803 chip If you open PJP8704, that the area A (see it on the pic) is completely isolated unless there is a problem on a chip (1-2-3). Your motherboard is the same as the pictures I sended

[DeniS182]

Re: Asus F555U dead

1,2,3,4, PJP8704 removed but nothing changed shorts here.. it's going inside motherboard and on components on both sides of the board..

[DeniS182]

Re: Asus F555U dead

definitely cpu is dead .. I cut off SL2614 - one side to cpu only and +3VA DSW short disappear and short is on cpu side..

Piernov and jasko_jacker thanks for answers.

[narada000]

Re: Asus F555U dead

Hi,

I also facing the same issue. When connected with the charger there no any lights, no power light. when press the power button nothing happened. I checked voltages as below,

3.3v available with the pwr button.
19.2v available with power section MOSFETs and resisters.

I checked the Winbond bios chip and it has 3.1v for pin 8

I'm a beginner at troubleshooting laptop motherboard and anyone can help to find the issue.

[narada000]

Re: Asus F555U dead

+3VA_DSW->+3VSUS , it takes the voltage from the pu8803 chip If you open PJP8704, that the area A (see it on the pic) is completely isolated unless there is a problem on a chip (1-2-3). Your motherboard is the same as the pictures I sended

yes I have this same motherboard with the same model numbers

[Logica]

Re: Asus F555U dead

I also have the same problem in two boards, I cut SL2614 as suggested by DeniS182 and I measure the short only on the CPU side. Two cards same problem !!!

[betamax22]

Re: Asus F555U dead

Hello, I also have x555uj. It doesn't hurt. 19 volts but no other voltage
can you help me

[polcastillo]

Re: Asus F555U dead

Sorry, a question someone know what are the mosfets that have top of the image? in boardview appears like PQ8302 &PQ8301I have in short this mosfets but in lens show me 6R0B06 and not appear neither replace.
Cheers from Argentina and so sorry for my bad english

[doncius85]

Re: Asus F555U dead

Hi, have dead X555UJ board. Short on +3VSUS line. When injecting voltage here all board is dead cold (monitored with thermal cam). Removed PJP8704, short is still there, but when connecting charger CPU starts to heat and there is a heat spot around PQ8811. Does that mean the CPU is dead?