Gaming Laptop Zephyrus S17 TFT not detected every time !

[titomno2]

Hi guys,
I post my problem here because I think it could be a capacitor related issue (Asus support on this particular subject is non-existing).
So the computer is a Zephyrus-S17-GX735LXS-26T and the strange behavior is seen.
On cold start most of the time the internal screen is detected and a picture it works fine until shutdown, sleep or deep sleep.
Then the screen won't work for a long period of time.
If I wait 1 or 2 hours it work again most of the time.
When it doesn't work the batterie indicator blink 3 times white stop and the same schematic is repeated until I stop the computer and wait a long time before starting again.

I have changed the LVDS cable with a brand new one ( I have the same issue).
BIOS have been checked and reuploaded without issue (except it did not solve the issue).

So after changing the LVDS I decided to not glue the screen again and checked the TFT board for damaged component.
The only issue I have seen is a cracked ceramic capacitor (but not in short circuit)


First piscture show the diode (which appear to be a zener diode but not sure and not very familiar with this SMD component, any help will be appreciated).
Second picture show the dent on the capacitor (I read 32kOhm increasing when putting probes on it).
Last picture shot the controller just under (i7248 H951850).

I don't have any screen compatible it is a 300Hz FHD with Gsync and it is very expensive (around 150 to 200euros for the screen itself).
Could the capacitor be the culprit and what is the value I must expect (can't find any datasheet on i7248 to see if there is any advice on the value)

My asumption is that something si missing on initalisation that prevent screen detection and therefore any activation.

Any help will be very appreciated, the end of warranty is of course overpassed and my friend put a lot of money on it.

Also it works fine on any external device (HDMI, DP).

[titomno2]

Some addition:
The laptop is with motherboard ASUS GX701LXS REV 1.3.
The TFT panel is a sharp LQ173M1JW03 (the pictures are from the board of the sharp panel).
Again don't hesitate to ask for clarification or details, it may help other peoples.

[mcplslg123]

When the internal screen doesnt work,do you get a picture on external monitor/numlock glows on keyboard?

Just want to be sure its intermittent posting issue or screen issue as the former is more common fault on these gaming series.

Replacing with a 50V/10uF capacitor is i beleive safe unless you know the exact specs.

[titomno2]

Hi mcplslg123, When the internal screen does not work, the battery led blink 3 time in white every 5s.
But the laptop boot (keyboard backalight, ssd working and if an external is connected I have picture and enter in windows without any issue).
So for me no post issue, the only annoying think is that the external dp and hdmi are only working once in windows not from boot (so no access to bios when the internal display is not detected).
I will try with 50V or 25V 10µF in first place this weekend.

[mcplslg123]

Dont use 25V and use 50V cap to be on safer wicket.

[titomno2]

Just forget to mention it is a 0603 package so for the moment it seems difficult to find 50V capable ceramic capacitor, still searching and 10µF seems also not far of the top available...

[pc_okay]

Hello, I think I have this damn panel in stock. I'll confirm this tomorrow if you want to test it. I had stupidly ordered it for a customer without seeing the PC beforehand, if it turns out it's the same PC... 😂 Anyway it wasn't the panel, I've seen a lot of machines at the moment that have these kinds of symptoms from all brands DELL, Lenovo... It could be bad luck: CPU or GPU balls that run away... or else a circuit of... it wouldn't be the backlight by chance that would blow? Have you checked with an external light source?

[titomno2]

Hello pc_okay, Indeed it's the only thing I haven't changed given the price (and it's not for me :-)). One thing to know the zephyrus at startup displays a logo with a fairly loud sound, when the screen no longer works not this intro sound, all the other functions of the pc are ok. I had checked the overheating before it is a machine with original liquid metal for the processor and it had been applied in the factory like pigs (it started to migrate) I replaced it with PTM7950 with phase change much safer. I have already changed the LVDS cable which seemed damaged to me at the hinge. I checked a defective backlight (no image even with a strong light source) and in addition at the socket the 3V is present at initialization as well as the 20V or 16V if only on battery. There would still be the switch chip between the dedicated GPU part and the CPU but I think that it would cause me problems under load (whether in burn or in game, the screen when it works only messes up if the power is cut). Basically it looks a lot like the start capacitor problems that we could find in the flat screens of the first PCs.





One thing is certain, I have more and more trouble with ASUS and its catastrophic after-sales service. We can't find any information on the fault codes displayed by the battery indicator (which is ok, 25% used but it works well). the 3 white LEDs, no one knows what that means. In the end, I repair DELLs and ACER Nitros much more easily!!! Thanks for the help. My colleague's kid put a lot of pocket money and odd jobs into this machine hoping it would last and a few days after the end of the warranty it started doing that!

[mcplslg123]

Just forget to mention it is a 0603 package so for the moment it seems difficult to find 50V capable ceramic capacitor, still searching and 10µF seems also not far of the top available...

You can use any smaller package cap with the help of soldering iron.

[pc_okay]

I have the panel in stock at least the equivalent: B173HAN05.1 If you are in the Paris region? Have you checked the LID_sensor anyway? (I don't really believe it but you never know)

[piernov]

English-speaking forum.

[titomno2]

Hi pc_okay, I'm not in paris region, I am more near Rennes. I could buy it if the price is not too much we may talk about it in PM.
Indeed testing an new panel could be a good test to check but the problem is the price for my colleague (and essentially if is not the culprit at the end). I will check the referencies as I already have an issue in the past when using not exactly the right panel.
Regarding the lid sensor it was my idea but one the boardview and schematic indicate that tere use to have to lid sensor but I found only one (the second was for a feature that seems to be managed with angle calculation) and second normaly on defective sensor lid it should prevent the start at all or cut off the computer any time.

Hi piernov, really sorry In my job I'm use to answer in the same language and my french pride kicked in. I understand it will help more people in that way and will pay attention to answer in english. Thank you for the translation by the way.

[titomno2]

Following request of moderator to keep the forum clean and usable I have posted the boardview and schematic in the following post.

[titomno2]

Hi, some updates.

I have unsolder the 0603 capacitor on the board of the panel => measurement was tricky and capacimeter telling something like 2.6µF (but I have sometimes lower readings in nF).
So I replaced with a murata 0603 1µF 10V (ce closest as I have) (25V and 50V are very low capacitors from 22nF to 100nF not much).
As it is the initialisation chipset the voltage must be 3.3V (I have measured only 3.3 and 16 to 20V for the main power (assuming for the backlightning).
Powering the laptop from cold => Screen works and I was able to play more than 1hour on forza at full FPS.
Powering OFF once cooled down after the game (CPU around 44 to 50°C).
Wait until the keyboard show no sign of life.
Powering ON again and no picture but computer boot properly (hear windows sound) => plug external monitor on the DP port and I have picture on the external monitor.
Log in, ask for reboot and both screen works => never happened before.
Powering OFF again until no sign of life.
Powering ON again and no picture on the internal monitor, laptop boot properly and picture on the external display.
Ask for reboot and again the picture is on both monitors.

So I'm a bit confuse and I should test the following but ask for any opinion about that:
1. waiting a long time before trying a cold power on.
2. Reinstall windows (but need obviously that internal monitor works and more than one time some times because external display works only when windows is loaded with nvidia driver).
3. changing the value of the capacitor (I don't have any new but can remove one from a board (see 0603 22µF 8.4V).
4. changing the panel but a no go for my friend because of the price and also because nobody is sure that it is the panel the culprit.

We talked about the solder ball on the processor, indeed it is a hot one and it go very high in temperature quickly (cycling mais have damaged or cracked some solder joint) but the behaviour I have described is strange for me.
Most of the issues with solded ball conduct to no post or bad beahvior under stress which I never experienced.

Have a nice week end.

[pc_okay]

I don't think reinstall of Windows Will fix it, if you don't have bios access or Asus logo during boot.

Do you have backlight with no picture or totally shutdown?

We have schematic and boardview, that's great and rare with ASUS ! You may check page 41 of the schematic: U4508 pin 2 (EN), 16 (SEL 1) and 17 (SEL2) and around.
Mesure SUPER CARREFULY value when screen is working and when blank screen. And post here or refer to the table on the right.

[titomno2]

Hi pc_okay,
Indeed you think it could be an issue with the switchable edp.
I will check if I can do that because it is at the worst place possible juste under the heatpipe of the heatsink ! between the gpu chip on the left and the processor on the left (the 42 chip)

I cannot remove the heatsink as it heat up so much quickly I will certainly kill the processor in the operation.

I will look after that this weekend if I have enough time to do so.

Thanks for the Idea.

[pc_okay]

Yeah that suck, it's a risky business.
You can put an old radiator on each cpu/gpu but it's pretty dangerous...
And if you try to mesure pin on U4580 be very carefull (don't short 2pins with your probes) some are directly connected to cpu/gpu.
You better take value on resistor connected to pins.
Check Q4504, good luck to find it with this boardview... 😐

[titomno2]

I think you where talking about the U4508 (can't fin the U4580), neither the Q4504 (it is on schematic, but not on boardview (when searching for it, adobe give me the space for left fan !!!
Whatever at first the screen was working fine (start, restart and stop) stopped to working when asking for deepsleep.
I was only able to measure the EN PIN 2 of U4508 and it show a proper 3.3V in all condition (screen working or not), also confusing that I have each time a picture on HDMI and display port.

I give you the picture of the area (I don't have any heasink that can work on the processor which heating like crazy right at startup and with proper heatsink.

So the last safe think to do will be to try a new panel (hope some one can propose the compatible screen at good price ;-)).

For the rest the computer is working fine and there is too much sensitive line in the area that may kill CPU or GPU.

I remain opened to any new Idea.