Legion Y540-15IRH no display

[dawidfryn]

Legion Y540-15IRH motherboard NM-C221 Rev: 2.0
the laptop turns on with no image, the keyboard lights up. No voltage on the four coils marked in the photo pl3001, pl3002, pl3003 and pl3004. Voltages and resistance of drmos pu3001:
1- 20v, 3M
2,3,4- 0V, 1,8ohm
5,6,7,8,9,10,11,12,13- GND
14- 19V, 3M
15- 1475V, 8,4M
16- 3,27V, 37,2K
17- 0,220v, 49,7K
18- 1,23V, 2,93M
19- GND
20- 3,02V, 14K
21- 3V, ol

[DeXXter]

The resistance on v_core seems fine, have you checked if the pwm administrator is working? Or if it's enabled?. Also check the coils around the pch, it shouldn't be that hot (I think).

[DeXXter]

The resistance on v_core seems fine, have you checked if the pwm administrator is working? Or if it's enabled?. Also check the coils around the pch, it shouldn't be that hot (I think).

[dawidfryn]

sorry for my poor english. Could you tell me exactly what I should check?

[DeXXter]

sorry for my poor english. Could you tell me exactly what I should check?

If I'm not mistaken that hot spot 42°c is the pch, it should not be that hot, check the coils around. The pwm ic for v_core (those coils you marked) is the one by their side. You should check the schematic or a boardview to find the ENABLE pin. Now to check pwm pulses you need an oscilloscope. But I would check PCH first, it's definitely too hot. Check the coils around, and the little capacitors above the chip.

[dawidfryn]

If I'm not mistaken that hot spot 42°c is the pch, it should not be that hot, check the coils around. The pwm ic for v_core (those coils you marked) is the one by their side. You should check the schematic or a boardview to find the ENABLE pin. Now to check pwm pulses you need an oscilloscope. But I would check PCH first, it's definitely too hot. Check the coils around, and the little capacitors above the chip.

Pl2101 46ohm capacitors on pch have resistances of 45ohm and kohm, no short circuits. I don't have an oscilloscope, but measurements with a multimeter show PWM for these 4 coils at 1.475V

[DeXXter]

Pl2101 46ohm capacitors on pch have resistances of 45ohm and kohm, no short circuits. I don't have an oscilloscope, but measurements with a multimeter show PWM for these 4 coils at 1.475V

I see, that seems fine, can't be sure without an oscilloscope though, but still no short (In any case check all the pins on that pwm ic, the one on the right of the coils using the datasheet). What is weird and make this a hard one is that you don't have vcccpucore, try to turn on your laptop, but with your multimeter on the coils, maybe you have voltage at the beginning. I had almost the same issue on a MSI katana and it was a cracked cpu (I had vcccpucore on mine though).
The other thing you can do is check the power on sequence and since vcccpucore (v_core) is one of the last voltages on the sequence you should check the voltages than comes before that, you find this list on the schematics, usually at the end.

[piernov]

If I'm not mistaken that hot spot 42°c is the pch, it should not be that hot, check the coils around.

PCH getting warm when working is expected.

[DeXXter]

PCH getting warm when working is expected.

Yeah I know, it just seemed a little too much since he didn't have v_core, but I guess it's normal on 9th/10th intel gens, I had a 11th that was always cold.

[mcplslg123]

The basics are ignored. What is the resistance to GND on vcore coils?
VCCSA is present or not?
1.8V rail is present or not?
1.2V/2.5V rail is present or not?
Bios with me cleaned flashed or not?