Asus Zenbook UX433F (very light water damage)

[corrize]

Hello, I have this sub notebook. I5, 8Gb soldered, build in 2019.
It has a very little water damage in processor power driver zone: I easyly removed superficial oxidation with thootbrush and the board is very clean. And I don"t yet cleaned with flux. 4 caps still have traces but no true damage and no short.

I measured 5 Ohms at some pins around the driver chip.
From your experience, it is normal around this kind of chip pls ?

The true problem is maybe that I don't found any issue, no true short anywhere. I don't know if the board works or not, and I'm scared to power on for testing. Thx.

[corrize]

Re: Asus Zenbook UX433F (very light water damage)

There is a list or « normals » resistor measures (or range) we should have at coils of all power supplies on a OK motherboard pls ?
And same for diode mode ?
I would like to check if the board is OK before power on, but I don’t know how to.

[Sephir0th]

Re: Asus Zenbook UX433F (very light water damage)

Low Ohms Reading (below 10 Ohms) around CPU/GPU are normal. But Check the Résistance to GND of your Main Power Rail before powering on the Board. Rails Like 3.3V, 5V and ,19V usually reads O.L.

We could could give you a 99% Prognose If you Share the exact Résistance to GND values in Ohms Mode, range 200 of each coil soldered on the Board and the Main Power Rail, Maybe drawed near the coils on a picture Taken of the Board.

[corrize]

Re: Asus Zenbook UX433F (very light water damage)

Thx for the help, I identifyed some components and wrote on the picture.
For coils (to ground) :

1 – (close CPU) 63 Ohms
2- (close CPU) 20 Ohms
3- (CPU) 3.6 Ohms
4- (CPU) 3.6 Ohms
5-(close CPU) 3.5 Ohms

6 – (3.3v) - Open line
7 – Battery – Open line
8 – ? Open line
9 – (Ram) – 300 Ohms
10 – (5v) – Open line

I guess all rails are OK ?

[Sephir0th]

Re: Asus Zenbook UX433F (very light water damage)

Well done, Only Main Power Rail is Missing but the value there is important too. The other Rails seems fine Like you already guess.

Measure on the Current Sense Resistor (any Side) shown in the Picture below.

[corrize]

Re: Asus Zenbook UX433F (very light water damage)

Thanks for looking in the good direction ; at the right of mosfets, there is 3 « blackcaps ». You can see on this best quality picture. I guess it's caps. The 3 are shorted (side to side, not to ground).
At shunt resistor, I mearuring 2KOhms but the value moving permanently very slowly to 40 MOhms, so not usefull until 3 caps are replaced.
It is possible to deduce capacitors values ? There is no schematc for this laptop, but I have shematics for another laptop (gamer) and at the power jack, there is 5 capacitors in parallel :
10uF x2 (size : 0805)
0.1uF x2 (size : 0402)
2200pF (size : 0402)

I guess I can deduce at least 1 of 3 is 10uF but the others ? Maybe another 0.1uF ?

[SMDFlea]

Re: Asus Zenbook UX433F (very light water damage)

Thanks for looking in the good direction ; at the right of mosfets, there is 3 « blackcaps ». You can see on this best quality picture. I guess it's caps. The 3 are shorted (side to side, not to ground).
At shunt resistor, I mearuring 2KOhms but the value moving permanently very slowly to 40 MOhms, so not usefull until 3 caps are replaced.
It is possible to deduce capacitors values ? There is no schematc for this laptop, but I have shematics for another laptop (gamer) and at the power jack, there is 5 capacitors in parallel :
10uF x2 (size : 0805)
0.1uF x2 (size : 0402)
2200pF (size : 0402)

I guess I can deduce at least 1 of 3 is 10uF but the others ? Maybe another 0.1uF ?

The 3 parallel « blackcaps » are inductors/ferrite beads.

[corrize]

Re: Asus Zenbook UX433F (very light water damage)

Ha ok thanks, I never saw that before. I was amazed that they were so clean.

[corrize]

Re: Asus Zenbook UX433F (very light water damage)

Update : I plugged the charger (battery unplugged) and measured 24v at gates of 2 power jack mosfet (last picture).

19v rail is OK

I measured some pins at charging IC and I noticed ACDRV : 24v and no voltage for battery (0.22v for HIDRV ans PHASE pins).

ACN : 19v
ACP : 19v
CMSRC : 18.9v
ACDRV : 24v
GND : 0v
LODRV : 0V
REGN : 6v
BTST : 5.8v
HIDRV : 0.22v
PHASE : 0.22v
VCC : 19v

So charging IC dead ?

[corrize]

Re: Asus Zenbook UX433F (very light water damage)

Update : this board is faulty, I plug the charger, the board is cold, vrms (coils 2,3,4,5) are at 0v and after 3-4 min, (I don’t press power button) lot of heat starting around CPU : vrms (coils 2,3,4,5), 5v coil and CPU itself. I measured 1.1v at vrms (coils 2,3,4,5).

The problem is ; I don’t find something faulty for starting diagnose.

- vrms : 0v is an issu but they work
- 24v at the gates of jack mosfets is an issu (I guess) but 19v is present
- below, all secondary voltage seems good (except vrms), and maybe batt voltage but battery is removed
- below, all voltages of charging IC, I don’t thing it is faulty ; ACDRV : 24v is finally good, battery is not plugged so maybe batt voltages are normals and LDO (pins 23 to 27) not working.

Do you see something faulty in the measurments pls ?

Voltages at all coils :
1 – (close CPU) 63 Ohms : 1.05v
2- (close CPU) 20 Ohms : 0v
3- (CPU) 3.6 Ohms : 0v
4- (CPU) 3.6 Ohms : 0v
5-(close CPU) 3.5 Ohms : 0v

6 – (3.3v) - Open line : 3.3v
7 – Battery – Open line : 0.2v (battery not plugged)
8 – ? Open line – 1.8v
9 – (Ram) – 300 Ohms : 1.23v
10 – (5v) – Open line : 5v

Charging IC
1 - ACN : 19v
2 - ACP : 19v
3 - CMSRC : 18.9v
4 - ACDRV : 24v
5 – ACOK : 5.9v
6 – ACDET : 2.66v
7 – IADP : 0v

8 – DCHG : 0v
9 – PMON : 0v
10 – PROCHOT : 5v
11 – SDA : 3.2v
12 – SCL : 3.2v
13 – CMPIN : 0.25v
14 - CMPOUT : 5.9v

15 – BATPRES : 0v
16 – TB_STAT : 3.2v
17 – BATSRC : 0.22v
18 – BATDRV : 0.25v
19 - SRN : 0.22v
20 – SRP : 0.22v
21 –ILIM :1.16v

22 - GND : 0v
23 - LODRV : 0V
24 - REGN : 6v
25 - BTST : 5.8v
26 - HIDRV : 0.22v
27 : PHASE : 0.22v
28 : VCC : 19v

[Sephir0th]

Re: Asus Zenbook UX433F (very light water damage)

Your DC-IN Circuit seems fine, so you can Stop troubleshooting there.

So all voltages present but No Picture? Test CapsLock responding in external Keyboard? If Not, you should continue Flashing known working BIOS, to exclude that It's corrupt. Auto-starting could be normal when No (CMOS) battery is present

[corrize]

Re: Asus Zenbook UX433F (very light water damage)

Capslock test is OK. After, yes, black screen.
What does it means ? Fan no spinning, it is not an issu ?
In my mind fan spinning : MB OK. And only after, if screen is black : BIOS issu. I’m wrong ?
I will try to flash bios. It is not normal bios, it is Winbond one.

Before, I will test too the charging IC with battery plugged according this thread with Asus too and same charging chip (BQ24780S) :
https://www.badcaps.net/forum/showthread.php?p=891723
It’s juste to be sure because I did not yet see battery charging.

[Sephir0th]

Re: Asus Zenbook UX433F (very light water damage)

That's a Bit weird right now, because responding Caps Lock means usually your BIOS is fine. Did you checked with external Monitor too? Disconnect the internal Display First (Remove all Power before), when Checking.

I'd leave the "issue" with the battery Like it is right now, Till the No Picture issue is troubleshooted properly.

You could also Check whether Only the Backlight is Missing in internal Display.

[corrize]

Re: Asus Zenbook UX433F (very light water damage)

You are right, it works.
The thing to know is when the battery is removed or empty, the laptop has a strange behaviour ; when the battery is plugged back, the led ol the power button key keep on but the laptop don't start, even pressing this power on button.

The charger must be unplugged, and plugged back one more time and few moment later the laptop start itself.
Before learn how to repair laptops, maybe I should learn how they works.
Great thanks for the help

[Sephir0th]

Re: Asus Zenbook UX433F (very light water damage)

You're Welcome!

Sometimes a Bad battery can cause in weird behaviour of the Laptop. But we don't have all the needed Infos yet for this conclusion. If a Strange behaviour with the battery still lasts, you're Welcome to come Back Here.

Kind regards

[ktmmotocross]

Re: Asus Zenbook UX433F (very light water damage)

Laptop start because battery is used as bios battery