ASUS Zenbook UX334FAC (UX334FL REV2.0) - No Display. Fell off the table.

[gjgib]

Hi again!

-Laptop fell from the table.
-Motherboard -seems- intact.
-It turns on kinda normal but NO DISPLAY, NO BACKLIGHT.

I'm not too familiar with ASUS laptops yet. I'm using a similar laptop model Boardview. (UX333FN REV2.0)

I feel there might be something wrong with these coil impedance values yet the voltage values go normal.


COIL = VOLTAGES (adapter powered) = IMPEDANCE TO GND (off and unplugged)

+VCCSA = 1.0V = 22ohm
+VCCCORE1 = 0.8V = 3.5ohm
+VCCCORE2 = 0.8V = 3.5ohm
+1.05VSUS = 1.05V = 59.ohm
+1.2V = 1.2V = High-fast fluctuations (weird)?
+1.8VSUS = 1.8V = 27.3k ohm
+3VA_DSW = 3.3V = 31.5k ohm
+5V = 5.1V = 22k ohm
+5VSUS = 0V = 6ohm
P_CHG_RSENS_SHAPE = 0.28v = 500k ohm

+VCCGT = NC = NC
+1.3VSG = NC = NC

+1.2V seems to have a -stable-voltage-value meassuring with multimeter but in resistance mode it just goes crazy.
+5VSUS missing.

Boardview seems to be in some $ites. If anyone has it would appreciate if can share. Thanks in advance!

[nikolayu]

Does it output the picture on HDMI?

[gjgib]

nikolayu Hi good sir. Nope, doesn't seem to be giving HDMI video and I use the cable everyday. Do I have to look out to test with another cable or is not usually a problem?

Btw, monitor already says no signal after plugging HDMI cable in the laptop board(without adapter power), when usually in desktop boards it waits till I turn board on or plug it to power at least.

Would that be a problem or na?

edit1: +5VS_HDMI = 5.1V

[SMDFlea]

You can request the boardview here -> https://www.badcaps.net/forum/troubl...ew#post1750354

[gjgib]

I still don't know what the +5VSUS is and how does it work. Is it an important early value for board to go on? I thought it was something like SUSpended. So it came in after board was hybernating or something.

[mon2]

+5VSUS = 0V = 6ohm

Resistance to ground is very low @ 6 ohms.

BV file has been posted here:

UX334FL 2.0 UX434FL MB_8G_I5-8265U_AS_R2.0 BV File - Badcaps

[gjgib]

mon2 Oh, thanks a lot. I'll be right on it. Sorry if I ask much mon2, but could u gift me a brief 20-word description about +5VSUS? Kinda struggling to get it right. What powers, when, for what, etc. Please.

Or if u know a guide or book, appreciated!

[mon2]

+5VSUS will be a low current power rail for suspend or perhaps even ALWAYS ON support of components such as the BIOS power rail. You have a low resistance on this rail so someone is very likely shorted. Do you have an adjustable power supply?

BTW - There is a very similar case to yours on this forum and exactly the same fault. The tech located the power supply IC for this +5VSUS rail and had to replace it to power the bios and the laptop was repaired. Will try to locate that thread in a sec for your reference.

Found it...

Is it safe to power up ASUS ROG G14 without TPS25810? - Badcaps

[mon2]

Locate mosfet PQ8801 using the above linked BV file. Remove all power. Inspect of possible liquid or damage to the parts.

Meter in resistance mode. Measure the resistance of this mosfet as follows:

source (1-2-3) & drain (5-6-7-8) ; select any of the pins in the group
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement. Checking to see if this mosfet is shorted or not.

[gjgib]

I think I misplaced couple components because of the similar model boardview I was using. I'll update everything and post it. Brb!

[gjgib]

COIL = VOLTAGES (adapter powered) = IMPEDANCE TO GND (off and unplugged)


+VCCGT = 0V = 5 ohm
+VCCSA = 1.0V = 19.5 ohm
+VCCCORE1 = 0.84V = 3.5 ohm
+VCCCORE2 = 0.84V = 3.5 ohm

+1.05VSUS = 1.1V = 53 ohm
+1.2V = 1.2V = High-fast fluctuations (weird)?
+1.8VSUS = 1.8V = 26.6K ohm

+3VA_DSW = 3.3V = 31.5K ohm
+5VSUS = 5.1V = 20.6K ohm

P_CHG_RSENS_SHAPE = 0.28v = 500k ohm

+1.35VSG = NC = NC


+1.2V seems to have a -stable-voltage-value while meassuring with multimeter but in resistance mode it just goes crazy and never stops.
+VCCGT missing)?

First time seeing this +VCCGT voltage, at least by that name. Can't tell if missing or if it comes in at a specific moment.

edit1: +VCCGT seems to be the graphics processor power supply. If is not on, I highly doubt it will give display.

Going deep...

[mcplslg123]

+VCCGT will rise only on load and almost irrevalent for posting. first check whether numlock light glows on usb keyboard. If yes then mb is posting. If not,then mb is not posting at all.So simply there cant be any display on screen/hdmi.
Moreover, VCCGT can be measured only with DSO. Multimeter often fails to catch the slight pulse while posting.

[gjgib]

Hi. Sorry for being late. I usually attack the problems with the suggestions quick enough but I was sick. I know it because the laptop keyboard has a led on CAPSLOCK key and is not blinking at the beginning nor when I press it after some seconds. USB keyboard key lights turn on but the CAPS/NUMLOCK are off and irresponsive.

Indeed the board is NOT DOING POST.

Gotta say that board comes in right after AC.Adapter is plugged in, probably because the battery is not connected. After pressing the ON/OFF button on the keyboard for some seconds, it goes OFF for 2 seconds but comes right back ON automatically. Would that be an EC/KBC/IO issue?

This is some EC meassurements I did. I don't think I see anything off but I'm yet to learn all the voltages.

At first I thought DGPU line was having issues then I saw there's no DGPU chip in this board model. So that voltage shouldn't matter right? Or it is still necessary for the CPU display line?


PS_ON_EC = 3.28V
VSUS_ON = 3.28
5VSUS_ON = 3.28V


+3VA_EC = 3.28V
+3VPLL = 3.3V
+3VS = 3.3V
1.2V_ON = 3.3V
3VA_ALW = 3.3V

DPWROK_EC = 3.27V
3VA_DSW_PWRGD = 3.3V
3VADSW_ON = 3.3V
3VSUS_PWRGD = 3.3V
PM_SYSPWROK = 3.27V
PM_PWROK = 3.28V
ALL_SYSTEM_PWRGD = 3.3V

AC_IN_OC# = 0V
EC_RST# = 3.3V
LID_SW# = 3.28V
RC_IN# = 3.3V
PM_SUSB# = 3.3V
PM_RSMRST# = 3.28V
PM_SUSC# = 3.3V
PM_PWRBTN# = 3.3V

DGPU_PWR_EN#_EC = 2.55V
DGPU_RST#_EC = 2.55V
DGPU_LIMIT = 2.55V

[mcplslg123]

Measurements shared on post#12 are correct.
DRAMRST# present?

[gjgib]

I don't think I see that 'DRAMRST#' voltage name in the EC voltages list. I'll leave the voltages# here just in case it goes with another name. If not, it may be hidden under the 'N83339956' stuff but I could track where it might be with some hints.

AC_IN_OC#
BAT1_IN_OC#
BUF_PLT_RST#
CAP_LED#
CHG_FULL_LED#
CHG_LED#
CVT_SNSR#
DGPU_PWR_EN#_EC
DGPU_RST#_EC
EC_RST#
EC_SCE#_PCH
EXT_SCI#
EXT_SMI#_X1
FN_LED#
IMVP8_VRHOT#
LCD_BACKOFF#
LID_SW#
LPC_FRAME#
MIPI_RESET#
OP_SD#
PCH_SUSACK#
PM_CLKRUN#
PM_PWRBTN#
PM_RSMRST#
PM_SUSB#
PM_SUSC#
PWR_SW#
RC_IN#
TP_DISABLE#

If not there I can check

[gjgib]

In this post about UX330UAR rev 2.1 no DISPLAY, DRAMRST# is missing. I tracked the line and it comes from the +1.2V through a Resistor which I don't know the value because the BV doesn't show.


My DRAMRST# could be similar. I'm using this BV UX334FL 2.0.

[gjgib]

Here I found something with different name that looks just like the line I've shown above.


Line +V_DDR_WR_VREF01_DIMM has 0.6V.

[gjgib]

Also meassured the RAM IC, don't seem to have any wrong values but the pin10-(P_DDR_LDO_EN_10) seems weird to me, maybe I'm wrong since it's a LDO Voltage. (Voltages in image, also)

[gjgib]

Couldn't find the RAM-IC anywhere. This is its inscription.

Marks: BCLBXA.

Boardview calls it: DOWN CONVERTER SYV731RAC//SILERGY QFN3*3-20

Btw, I know it kinda varies from IC to IC, but are these rails voltages usually around these values?
'BST' (4.5V)?
'P_DDR_LDO_EN_10' (2.8V)? Is this LDO ENable enough to be enabled/enabling?
'P_DDR_VTTREF_10' (0.6V)?
'P_DDR_FB_10' (0.6)?

I started seeing these voltages recent ago with some Charger ICs. Yet to fully understand them.
Are REFerence and FeedBack voltages half of the ouput value of the IC?

[mcplslg123]

These voltages seems ok to me. Feedback,EN LDO voltages dependes on the resistor value and pull up value.

[gjgib]

Thanks. The problem is that I couldn't find exactly DRAMRST# right?