Dell Latitude 5590 ,strange behavior

[kokono]

I got this board by melting pu613 IC.
I replaced it. Before that, I checked all the voltage rails. There was no short circuit. I also tested the CPU (PL610 , PL613 about 3.5 Ohm ,PL612 4.2 Ohm).
Currently, after pressing the start button, the Power LED and keyboard backlight turn on and off in about half a second.
I checked all the voltage rails, they are all present up to step S5.
From this point on, all the voltages come after pressing the start button, but they go quickly. I didn't find any short circuit in it.
I checked the board with a thermal camera but found nothing.
The only suspicious thing I found is the +PWR_SRC voltage, which is about 13.5 volts. But I am not sure that it is a problem.

i did not find the schematic of this model,but it seems to be very similar to the F391p( Dell Latitude 5290 ) model. i attached it
Please help me troubleshoot this board.

[mon2]

Re: Dell Latitude 5590 ,strange behavior

Remove all power. Meter in resistance mode.

Check the resistance to ground of +PWR_SRC.

[kokono]

Re: Dell Latitude 5590 ,strange behavior

Remove all power. Meter in resistance mode.

Check the resistance to ground of +PWR_SRC.

Thx, I've done it before. about 350K ohm

[piernov]

Re: Dell Latitude 5590 ,strange behavior

After FDMF3035 fails, CPU will most likely be dead. Very common problem on these. Always rely on warranty when possible.

[kokono]

Re: Dell Latitude 5590 ,strange behavior

After FDMF3035 fails, CPU will most likely be dead. Very common problem on these. Always rely on warranty when possible.

but CPU is not short , i think 3.5 ohm is normal

[piernov]

Re: Dell Latitude 5590 ,strange behavior

Doesn't need to be shorted to be bad.

[anshad]

Re: Dell Latitude 5590 ,strange behavior

but CPU is not short , i think 3.5 ohm is normal

Typical CPU core voltage is around 1v only (Exact value depends on the model and varies according to load via SVID). When a Mosfet shorts, it may send a pretty high voltage (PWRSRC/B+ volt) directly to the CPU. Most of the time, the CPU/SoC simply dies. I speak from my practical experience.

[mcplslg123]

Re: Dell Latitude 5590 ,strange behavior

13.5V on main rail is ok in this board 'coz of charging ic technology used here for narrow voltage. However, i fully agree with @piernov/anshad's view. Most likely its a dead SOC. You can try fixing the fault but it'll very likely result in no display although switching perfectly.

[kokono]

Re: Dell Latitude 5590 ,strange behavior

13.5V on main rail is ok in this board 'coz of charging ic technology used here for narrow voltage. However, i fully agree with @piernov/anshad's view. Most likely its a dead SOC. You can try fixing the fault but it'll very likely result in no display although switching perfectly.

Many thanks to all the experts.
Do you know the signals that I can use to confirm the CPU failure?

[Danila.]

Re: Dell Latitude 5590 ,strange behavior

but CPU is not short , i think 3.5 ohm is normal

What is CPU model ?

[Srky]

Re: Dell Latitude 5590 ,strange behavior

What is CPU model ?

From the picture I would say it's i7-8650u (SR3L8)

[Danila.]

Re: Dell Latitude 5590 ,strange behavior

I guess it's a less than have to will be

[mielta]

Re: Dell Latitude 5590 ,strange behavior

Hi
Remove coils PL610-613 and see what happend

[Srky]

Re: Dell Latitude 5590 ,strange behavior

Has anyone been able to fix this problem without replacing the motherboard?

[andresi]

Re: Dell Latitude 5590 ,strange behavior

i have problem with strange issue, before the laptop is no display, so i flash the bios then i check with keyboard its normal and capslock its response, but after i connected to screen the laptop cant boot normaly just no display and no response with capslock keyboard. i check with external monitor its good. i already change the lcd and cable flexsible, but still no display and no response anyone can help or give me some solution?

[Stevedb]

Re: Dell Latitude 5590 ,strange behavior

Hi do you have 19v and 3,3v on screen connector? Do you got the enable for backlight? BL ON ,

[Magnusa2]

Re: Dell Latitude 5590 ,strange behavior

i have problem with strange issue, before the laptop is no display, so i flash the bios then i check with keyboard its normal and capslock its response, but after i connected to screen the laptop cant boot normaly just no display and no response with capslock keyboard. I check with external monitor its good. I already change the lcd and cable flexsible, but still no display and no response anyone can help or give me some solution?

i have same issue
any soulution for this ?

[Magnusa2]

Re: Dell Latitude 5590 ,strange behavior

You have solution ?