Asus GL553VD, need expert advice !!!

[guizmo1967]

Hello,

Board Asus GL553VD

Resistance values:

Q8801
GD 3.6M
GS 11.7M
SD 12.8M


Q8802
GD .5M
GS 11.6M
SD 36.7K


Q8803
GD OL
GS 60K
SD OL


Q8804
GD 6.2M
GS 57.8K
SD 4M

I took a picture of my board and added some voltage values. Laptop does not turn on (of course !!)

One last question, how to know when BQ24735RGRR goes bad and when to replace it ?

Thank you !

[mon2]

Re: Asus GL553VD, need expert advice !!!

The last 3 mosfets look shorted with the low resistance. The values should be higher than the low kOhm readings.

To confirm, remove the ~4k resistor on the ACDRV pin and check if the resistance readings change or not. One bad mosfet can throw off the readings for the others.

[mcplslg123]

Re: Asus GL553VD, need expert advice !!!

Q8801/8802 are working as you do have 25V on gate(assuming they are N channel as pics are not clear).Measure voltage on ACN/ACP/ACDET/ACOK/REGN/VCC/ACDRV of charging IC.

[guizmo1967]

Re: Asus GL553VD, need expert advice !!!

Q8803 is HIGH-SIDE

Q8804 is LOW-SIDE

The output of this charge pump goes through L8800, R8809 and then to the battery connector but it's only 1.618V,the charge pump is not working ??

Asus GL553VD BQ24735RGRR voltage readings:

AC only AC + BAT

PIN LABEL
1 ACN 19.75 19.76
2 ACP 19.75 19.76
3 CMSRC 19.55 19.56
4 ACDRV 24.86 24.91
5 ACOK 3.18 3.18
6 ACDET 2.66 2.64
7 IOUT 0 0
8 SDA .03 2.32
9 SCL .03 0.22
10 CELL 2.93 3.05
11 BATDRV 3.13 1.640
12 SRN 3.13 1.618
13 SRP 3.13 1.618
14 GND 0 0
15 LODRV 0 0
16 REGN 6.02 6.02
17 BTST 5.88 5.86
18 HIDRV 3.00 1.617
19 PHASE 3.17 1.618
20 VCC 19.46 19.46

[mon2]

Re: Asus GL553VD, need expert advice !!!

Remove all power. Meter in resistance mode.

Measure the resistance to ground of the:

SCL
SDA

pins on the charger IC. Post your readings.

[mcplslg123]

Re: Asus GL553VD, need expert advice !!!

Besides following advice of @mon2 at post#5, do check resistance to GND of +3V LDO. Check +3V LDO is present or not. For this you need to probe your 3v PWM IC.

[guizmo1967]

Re: Asus GL553VD, need expert advice !!!

Remove all power. Meter in resistance mode.

Measure the resistance to ground of the:

SCL
SDA

pins on the charger IC. Post your readings.

SDA O.L
SCL O.L

Something weird happened yesterday and I have no idea why ! From the beginning when I was plugging the charger (without battery) no light at all were on and I had only 3.3V on a coil.

What I did is removed Q8800, soldered a wire from drain (drain had 19.76V) to R8809 and plugged the charger, still nothing ! Well I said to myself I better removed that wire since nothing happened. Later that evening decided to plugged the charger, again with the battery removed and to my surprise the battery light came on for the first time !!! I took my multimeter and began to take some measurements directly at some coils and now I had 3.3V, 1.0V and 5.0V ????

I decided to put everything back together, push the power button and voila the power light came on but black screen and no cpu fan, laptop was still dead but with two lights on now !! I never soldered back Q8800.

What do you think happened ??

[guizmo1967]

Re: Asus GL553VD, need expert advice !!!

I forgot to mention that I plugged the laptop to a monitor with HDMI cable and again black screen !

[guizmo1967]

Re: Asus GL553VD, need expert advice !!!

Hello,

I have decided to work on that laptop again, since I have new tools to work with and a little more experience !

Battery removed (it's dead, over discharged) I plug the charger, battery led turns on, solid amber, press power button, power led turns on, solid white but the laptop is not working, the cpu cold, gpu cold, cpu fan not running, black screen ! If I push the power button for 10 seconds, the lights goes off like it's supposed to, the laptop shuts down.

I plug a monitor through HDMI and still black screen !

I have flash more than 5 different bin to the BIOS chip, and nothing changed !

There are many coils on that motherboard, but a lot have no voltage except the +1.0V, +3.30V and +5.0V ??

Any ideas !!

Thank you !

[koby058]

Re: Asus GL553VD, need expert advice !!!

Try follow the power sequence and power good

[guizmo1967]

Re: Asus GL553VD, need expert advice !!!

I found the power sequence for the GL553VD motherboard, I will try to follow that one ....

Thank you !

[myth77]

Re: Asus GL553VD, need expert advice !!!

I dont know why you played with BQ24735RGRR chip and power main mosfets...because according to measurements from your first picture the BQ chip and mosfets are working fine and you have 19.7 volts on +AC_BAT_SYS main power rail. So, your problem, why motherboard is not turning on is somewhere else.
And now, because you have lights, ite chip is probably fine. Check pch chip and every coil on the board...if there is no short, maybe its bios issue. And please keep in mind that short on cpu and gpu coils are only if resistance is lower then 1 ohm. Few ohms are fine only for those rails.

[guizmo1967]

Re: Asus GL553VD, need expert advice !!!

I extracted the power supply page from the schematic and added JP point for every voltages on that chart with the boardview file I had.

Every coils on that motherboard and every JP point that I added on that chart are not shorted to ground, they all have resistance, the lowest was 1.6 Ohm.

I would like to know how do you test mosfet in circuit ? Diode, continuity or resistance mode ??

Me, for n-channel mosfet, I touch S with red probe and D with black probe and should read about 0.5V, reverse the probe, OL. No continuity between S and G for a good mosfet, is this the right way to test a mosfet ??

They are many mosfets around those coils who don't have voltage that don't measure good. Is this possible so many mosfet failed at the same time ???

Everything before and including AOZ2261QI-18 has good voltage but everything after that, 0V everywhere but nothing is shorted ????

[guizmo1967]

Re: Asus GL553VD, need expert advice !!!

Well this is the end for this post .....

I made a mistake yesterday (if you don't, you will never learn), I fried the cpu, now every coils around the CPU is shorted

But I would like to know why. All I did was removing U8300A, the PWM controller for Q8300 and Q8301. Why, because there was too many mosfets who where not measuring good and I just wanted to satisfy my curiosity, to me, Q8300 was shorted! But in the end it was a rookie move .....

This is the part I would like to understand. When U8300A was not removed and the charger was plugged in, the laptop was not turning on but there was light, it was a start.

Later that day, I forgot that U8300A was removed and I plugged the charger and the +AC_BAT_SYS went straight to the CPU, but why !!!

PWM controller not removed = CPU not fried !
PWM controller removed = CPU fried !

Thank you

[mcplslg123]

Re: Asus GL553VD, need expert advice !!!

Yes it will. PWM controller drives the gates of high/low side mosfets. Since PWM is missing, gates of mosfets are left open and thus 19V reaches cpu. If you ever need to remove a pwm ic for test purpose,always remove the mosfets linked with iy as well as coil. Then its safe to apply power.

[guizmo1967]

Re: Asus GL553VD, need expert advice !!!

Thank you, lesson learned, will not do it a second time !!!