Asus F540S turns on and does not give video

[diegito11]

Hello colleagues, this laptop has arrived with motherboard x540sa rev 2.1; The symptom is that it turns on but does not give video.
Add that the cpu heats up but the fan never comes on (verified that the fan works), I have reprogrammed bios with the latest version of the official website and another 2 that I found in this forum with the same black screen result bone no it does not even turn on the display.
I have doubts if the problem is in the integrated CPU and I would not like to make a reflow without making sure.
Say that when I connect the jack to the board it turns on only that the 2 LEDs that have the current one remain on steady and the battery one flashes constantly.
Connected to the laboratory source gives me an amperage of 0.25A.
I have checked the large coils and I do not find short but if I see something strange and it is that on the one hand it measures me one thing and on the other hand it measures me differently and continuously modifying
For example, one side measures me 1.09 and on the other 4.20 and changing to 4.34.4.40.4.50.4.60.
I measured on a 200 ohm scale and I am good about 108 on the other infinity coils.
I put the schematic that has cost me to find it, to see if you can give me a cable.

https://1drv.ms/b/s!ArCMHaOjRKmJ0XPf...Nj14b?e=UFmr6t

[SMDFlea]

Re: Asus F540S turns on and does not give video

"one side measures me 1.09 and on the other 4.20 and changing to 4.34.4.40.4.50.4.60"

What part are you testing ? ,post photos of the area .

[diegito11]

Re: Asus F540S turns on and does not give video

I pass the measurements of the coils and add the * as something strange.

* - It measures me of 4,69v changing and arrives 4,89v alternating in several measures, it does not remain fixed.I measure it again and it goes up to 4,46v.

[jasko_jacker]

Re: Asus F540S turns on and does not give video

Coil PL8600 -> ram voltage ->1.35V

What kind of multimeter do you use, has an autorange?

[diegito11]

Re: Asus F540S turns on and does not give video

I have a digital one but I have a partner who has an analog one in case you ask me for a measurement with him.
You want to tell me that pl8600 has to measure 1.35 but as I told you, it measures me more, what can be the component that fails?

[Techtiger]

Re: Asus F540S turns on and does not give video

check the voltage on coils with out power and with power again the RAM related setion coil shoul have PL8600 - 1.35V both sides and check PLTRST COREPWROK the SMD components are given in the Guide PDF

[diegito11]

Re: Asus F540S turns on and does not give video

He measured without current and with the 200 ohm scale polymeter and gives me on both sides 120.5, with current I already put it in the photo in the part of the capacitors 1.39 in the bottom where the mosfet are 7.77 and 8v.
Regarding COREPWROK above attached to the 1.39v memories at the bottom next to the 3.42v processor.

[digitalpc]

Re: Asus F540S turns on and does not give video

Ram voltage??
Do u have output with hdmi??

[diegito11]

Re: Asus F540S turns on and does not give video

I don't know where to measure the voltage of the ram.
Regarding the second question, VGA and HDMI have an output, but I don't know where to measure either, to give you the measurement.

[diegito11]

Re: Asus F540S turns on and does not give video

there is no one who can tell me where to measure?

[dj_ricoh]

Re: Asus F540S turns on and does not give video

Hdmi works sometimes after you install drivers.

[dj_ricoh]

Re: Asus F540S turns on and does not give video

Sio needs to be checked but if the thermal paste was hard then 99% needs reballing.

An oscilloscope will be good to see if the CPU works on coils.

[motanya]

Re: Asus F540S turns on and does not give video

Hello colleagues, this laptop has arrived with motherboard x540sa rev 2.1; The symptom is that it turns on but does not give video.
Add that the cpu heats up but the fan never comes on (verified that the fan works), I have reprogrammed bios with the latest version of the official website and another 2 that I found in this forum with the same black screen result bone no it does not even turn on the display.
I have doubts if the problem is in the integrated CPU and I would not like to make a reflow without making sure.
Say that when I connect the jack to the board it turns on only that the 2 LEDs that have the current one remain on steady and the battery one flashes constantly.
Connected to the laboratory source gives me an amperage of 0.25A.
I have checked the large coils and I do not find short but if I see something strange and it is that on the one hand it measures me one thing and on the other hand it measures me differently and continuously modifying
For example, one side measures me 1.09 and on the other 4.20 and changing to 4.34.4.40.4.50.4.60.
I measured on a 200 ohm scale and I am good about 108 on the other infinity coils.
I put the schematic that has cost me to find it, to see if you can give me a cable.

https://1drv.ms/b/s!ArCMHaOjRKmJ0XPf...Nj14b?e=UFmr6t

I have the same laptop with the exact same problem. Power on led powers on on charger connection, charging led blinking no display, cpu heats as well but the fan does not spin. Has anyone found the solution for this?