Asus x55a no power or bootup

[garrymc123]

Hi guys got this laptop in for repair wont boot or nothing i got the schematic for it and did some voltage checks and i have only 3.1 v on the first coil after the main power supply i have attached a picture with all the power supplies.. Can anybody point me on what steps to take next to trace the problem or what process to check next ..Thanks

[caspian]

Re: Asus x55a no power or bootup

in the boardview, find PU8100. then measure voltage on all its pins to find out which one is wrong.

[garrymc123]

Re: Asus x55a no power or bootup

Hi Caspian thanks for your reply the boardview i have do not match the motherboard i have
i will check tomorrow and find it on the motherboard and let you know thanks

[garrymc123]

Re: Asus x55a no power or bootup

is this PU8100 charging ic

[brew99]

Re: Asus x55a no power or bootup

What are the markings on that chip? I can't see anything in the photo

[garrymc123]

Re: Asus x55a no power or bootup

its bq25a

[brew99]

Re: Asus x55a no power or bootup

That is probably it

http://www.ti.com/lit/ds/symlink/bq24725a.pdf

[garrymc123]

Re: Asus x55a no power or bootup

ok here are the voltages for bq25a

vcc 18.76
phase 3.1
hidrv 3.1
btst 5.5
regn 6.0

lod 0.0
gnd
srp 3.1
srn 3.1
bati 3.1

ilim 0.8
scl 3.2
sda 3.2
iout 0.0
acdet 2.5

ac ok 3.0
ac drv 25.02
smcsrc 19.04
acp 19.02
acn 19.01


Thanks guys

[brew99]

Re: Asus x55a no power or bootup

In your first post you mentioned that you have the schematic? Do you also have boardview? Can you post that here for us to look at?

I'm just an hobbyist starting out in this stuff, but the voltages on the BQ24725a look fine to me. VCC,REGN, ACDET, ACOK all there. I'm assuming that the ACOK is being pulled to a 3V rail, and not suppose to be some other rail?

[piernov]

Re: Asus x55a no power or bootup

B+ rail is present so nothing to troubleshoot around charger IC, it's working fine.
Time to check the LDO outputs of the 3V/5V regulator.

[garrymc123]

Re: Asus x55a no power or bootup

Thanks, Brew and Piernov I couldn't get a schematic it was the wrong one I got a board view link but it also was wrong. I have attached a pic is this the 3v/5v regulator area

Thanks

[on/off]

Re: Asus x55a no power or bootup

Seem totally match with boardview from links provide by SMDFlea.

[garrymc123]

Re: Asus x55a no power or bootup

Seem totally match with boardview from links provide by SMDFlea.

I couldn't open that file with the boardview software i have its a fz file its usually a ASC file . What software do i require for the fz file thanks ON/Off

[on/off]

Re: Asus x55a no power or bootup

Open it with:
http://boardviewer.net/index
or
https://openboardview.org/

[garrymc123]

Re: Asus x55a no power or bootup

Thanks guys for the help much appreciated with the laptop got the boardview working piernov where exactly can i find the outputs of the 3V/5V regulator Thanks

[garrymc123]

Re: Asus x55a no power or bootup

Anyone??

[brew99]

Re: Asus x55a no power or bootup

I can't open a boardview file while I'm at work, but usually its a 20 pin or so chip. On my Asus X541UA machine the 3V/5V is a RichTek RT8249C, although I don't believe it was labelled that on the chip (looking back at prior docs I downloading for fixing it!).

Can you indicate the markings on some of the 20 pin chips that you think might be, and we can go from there? Should be a couple of coils and FETS near it

[brew99]

Re: Asus x55a no power or bootup

It's PU8100 on the other side of the PCB in the corner. It's an RT8206 chip, 32 pins

https://www.richtek.com/assets/produ...S8206LM-07.pdf

The previous chip you were looking at (BQ25a) was the charger IC.

Look at the linked datasheet and measure outputs (use the boardview and search for PU8100)

[garrymc123]

Re: Asus x55a no power or bootup

Cheers brew99 i will measure voltages and get back to you with the results.

Thanks

[garrymc123]

Re: Asus x55a no power or bootup

Right here are the measurements for the power management chip

1 ref - 2v
2 ton- 0.0v
3 vcc - 5v
4 enldo- 06.39
5 nc - 0.0v
6 vin -19.25
7 ldo - 5v
8 nc - 0.0v
9 byp - 0.0v
10 vout1 - 0.0v
11 fb1 - 0.0v
12 ilim1 - 1.816v
13 pgood1 0.0v
14 en1 - 03.1v
15 ugate - 0.0v
16 phase1 - 0.0v
17- boot1 - 4.2v
18 - lgate1 0.0v
19 - pvcc - 5v
20 - secfb - 0.0v
21 - gnd
22 - gnd
23 - lgate2 - 0.0v
24 - boot2 - 4.5v
25 - phase2 - 0.0v
26 - ugate2 - 0.0v
27 - en2 - 0.0v
28 - pgood2 - 0.0v
29 - skip - 0.0v
30 - vout2 - 0.0v
31 - ilim2 - 1.3v
32 - fb2 - 0.0v

Thanks