Lenovo IdeaPad 305 (Mobo: LA-B092P Rev.3.0) - Faulty PCH/CPU module ?

Hello,
Laptop: Lenovo IdeaPad 305
Motherboard: LA-B092P Rev.3.0
I am looking for confirmation of the fault please.
When I press power button laptop starts and after few second shuts down (no signal on internal or external screen).
20V, 5V and 3,3V is present. I have measured resistance to the ground on all coils and PL1102 was very low.
I have removed coil to measure resistance on both pads and low resistance is on +CPU_CORE side.
This is MCM chip (PCH and CPU as one module). Can low resistance be clear indication of faulty MCM ?
Laptop most likely was overheating (I have removed from cooling radiator a thick layer clumps of dust).
Thank you in advance.
Regards,
Rafal S.

For 99.9% it is a faulty hybrid CPU. Best would be to confirm that by performing a short test described in TRAININGS subforum: szkolenie-nr-1-podstawy-diagnostyki-plyt-glownych-laptopow-t986.html (1.5V @ 3-5A on the pin of PL1102 which indicates a short circuit to ground).

Thank you for your confirmation and advice.
I have applied 1,5V and 3A to the side with low resistance and voltage drops to very low value immediately and almost full current still flows (dead short).
I did use thermal camera to confirm what is getting hot and it was part of hybrid CPU (on PCH side).
I am sure that you are doing hundreds more laptops repairs than I do so from your experience are these hybrid CPU's failing often ?
If yes is it bad manufacture process or users not thinking of dust removal and overheating them ?
You have created very valuable forum. Good job.
Regards,
Rafal S.

RafiManch ha scritto:I have applied 1,5V and 3A to the side with low resistance and voltage drops to very low value immediately and almost full current still flows (dead short). I did use thermal camera to confirm what is getting hot and it was part of hybrid CPU (on PCH side).

So definitely PCH part of hybrid CPU has gone and CPU needs to be replaced. But I think is beyond economical repair as you can get a fully working logic board cheaper than a hybrid CPU.

RafiManch ha scritto:from your experience are these hybrid CPU's failing often ?

Not quite often on machines I repair (Apple), however, more often on others (like Lenovo, Toshiba, Acer etc).

RafiManch ha scritto:If yes is it bad manufacture process or users not thinking of dust removal and overheating them ?

Quite often there is an overheating or liquid spillage result that those hybrid CPUs fail. I think there is also some kind of bad design if the logic board allows CPU to overheat.

Thank you for your support as always.
Have a good day.