Lenovo IdeaPad L340-15IRH FG541 FG741 NM-C362 water damage no GPU power

[huzo]

The board is FG541 FG741 NM-C362, and the laptop was water damaged,but not too much.

I cleaned the board and laptop was blinking white light , 3.3V and 5V were present, CPU had no power, i analyzed the startup sequence and found that there is no VCCSA on the CPU, i traced it to the PU2901 and found the Vin pin 47 had no input, resistor 2Mohm was burned OL, replaced that and now the CPU is getting hot and i get the keyboard backlight now and fans spin, but still blinking white light and no image on the screen, but now the GPU is cold, and i remember when i first took the board the GPU was getting hot and now it isn't anymore...there is still VCCIO present on the GPU ,but the GPU is not powering up, or something else is going on? I tried flashing different bios, it's the same...

Could someone help what is needed for powering GPU from schematics? I always get mixed up with necessary signals, since i am stil llearning laptop repair , and i need someone to explain some stuff beacuase i learned myself...

i have attached the boardview and schematics....

[SMDFlea]

Please post a link to the schematics/boardview if they`re posted already on the forum.Otherwise,post the schematics/boardview in the "Schematic requests ONLY!" section (where everyone can find them) ,then post a link to them from this thread

Reminder: rules and organization of this section
https://www.badcaps.net/forum/troubl...f-this-section

[huzo]

Sorry admin.


https://www.badcaps.net/filedata/fetch?id=2064011
https://www.badcaps.net/filedata/fetch?id=3301145

[huzo]

anyone please?

[huzo]

There is no NVVDD in Power Sequence ,the before voltages are present +1.8VS_AON,+1.8VGS ,and no NVVDD..... NVVDD_EN_R is 3.3V, but there is no NVVDD_PWRGD_R...should i check anything else before replacing the PU7501 controller?

[huzo]

replaced the controller...still no power to the GPU.... can anyone help what to do next?