Asus K55vd motherboard dead no Leds

[Bisketti]

Hi help needed Im working on Asus K55vd motherboard. It wont switch on drawing .40ma. I have +3VA0 and +5VA0 but no output across Pl8101 or Pl8100.
RT8239 3.3v/5v reg.
Signals present are D6806 PWR_SW# 3v drop to 0V when power buttons pressed.
c3022 pm_syspwrok .34mv
D3022 +3vA_ec and ec_rst 3v
I have tried reflashing the bios but still the same.

Cant find the schematics I only have the boardview file and the repair guide.
Any help appreciated

K54LY repair guide https://www.badcaps.net/forum/showthread.php?t=124897

.

[meritosari]

Re: Asus K55vd motherboard dead no Leds

Hi help needed Im working on Asus K55vd motherboard. It wont switch on drawing .40ma. I have +3VA0 and +5VA0 but no output across Pl8101 or Pl8100.
RT8239 3.3v/5v reg.
Signals present are D6806 PWR_SW# 3v drop to 0V when power buttons pressed.
c3022 pm_syspwrok .34mv
D3022 +3vA_ec and ec_rst 3v
I have tried reflashing the bios but still the same.

Cant find the schematics I only have the boardview file and the repair guide.
Any help appreciated

How about signal VSUS_ON? its appear after pressing power button?

[Bisketti]

Re: Asus K55vd motherboard dead no Leds

Yes pin 86 of U3001 3v even without pressing powerbutton

[meritosari]

Re: Asus K55vd motherboard dead no Leds

+12VSUS already steady?

[Bisketti]

Re: Asus K55vd motherboard dead no Leds

No +12vSUS, where does this originate?

[meritosari]

Re: Asus K55vd motherboard dead no Leds

I've Compare it with asus x450cc and x200ca, +12VSUS, stand by after plug in adapter.

+12vsus coming from charge pump from 5VAO rail, this voltage for input load switch mosfet to generate to VS or V (mark ie 3vs, 3v) many voltage rail.

You can see in datasheet RT family.
More easy to understand BV (boardview) with other schematic, like asus UX31A2.

How many volt on pin 2 and pin 4 IC RT8239?

[Bisketti]

Re: Asus K55vd motherboard dead no Leds

Thanks for the input Pin 2= 5v, pin 4 =1.97v

[Bisketti]

Re: Asus K55vd motherboard dead no Leds

Thanks for the input Pin 2= 5v, pin 4 =1.97v
Psl8100 +5va0-- +5va
psl8101 +3va0-- +3va

Pq108
pin 3= 4.86
pin 6= 0v
pin 5= 0v
pin 2 =3v

u3001 sio
pin 80 = +5VSUS_PWRON_EC 0v
pin 86 = VSUS_ON 3.3v
pin 74 = +3vacc 3v

[meritosari]

Re: Asus K55vd motherboard dead no Leds

this is the right repair guide for this model that could be help to make measurement on many important points. but still not really help to understanding to BV.

you can follow the power sequence to analize where voltage or signal has stopped.

Here PS for asus x450cc there are bit different for K55VD.

1.+AC_BAT_SYS
2.AC_IN_OC#
3.+5VAO /+5VA
4.+3VAO /+3VA
5.+3VA_EC
6.EC_RST
7.5VSUS_ON
8.5VSUS
9.12VSUS
10.PWR_SW# POWERBUTTON
11.PM_PWRBTN#
12.3VSUS_ON
13.+3VO AND +5VO
14.3VSUS_PWRGD
15.RSMRST#

Don't forget to make sure PL8100 and PL8101 have no short on those both coils

[Bisketti]

Re: Asus K55vd motherboard dead no Leds

Great I will check it out tomorrow. Many thanks for your help.

BTW pl8100 is ready 1.7 ohm when I remove solder from pjp8102 i side +3vsuso = 52k ohm and other side +3vsus = 1.7ohm so something must be wrong on that line.