Dell Latitude 5410 dead help please.

[gugutm]

hi everyone,
need some advice i am not professional just junior , but maybe someone could help me please
i have
Device : Laptop
Brand : DELL
Model : LATITUDE 5410
Board Number: FDZ41 LA-J371P Rev:1.0
i am attaching schematics and board view. [MOD EDIT] Link to schematic - https://www.badcaps.net/forum/troubl...14#post3484414

my problem is its not turning on , i follow the video with a similar board of dell 5400 in youtube ,as i said i am not pro, i am getting 19v true the first 2 mosfets which is pq9 and pq4 then i went to check what i am getting on current sense resistor pr700 and i am getting 19v too from there i moved to pq700, pq701 and in here i am start getting not 19v as board view shows but 16.80v
i noticed on pq700 pin 1234 19.89v but pin657 16.80v
and i dont understand , in my understanding its not right,
video advising to measure on a pq701 mosfet in diode mode red prob to the ground and black on pq701 on pin 3/4 and i am getting 0.504v which is good about the same is on pq700.
i measured power on button and instead of 3v i am getting 0.9v
then i used thermal camera to see what is heating up and PU2 was quite hot 38c but when i measured i am getting on pin1 19v and on pin 3 3.3v so its good
and 2 more was heating up pu700 and pu701

i hope that helps what i said , i tried to explain as best as i can to my knowledge.

many thanks
gugutm

[gugutm]

Hi There no one could help please or advice ?

[reformatt]

It's a NVDC power supply, so main power rail is equal to battery voltage so looks normal to me. First thing is to power off, check all coils resistances to ground. CPU/GPU coils will measure very low. CPU should be a few ohms or more, but not 0. GPU coils often measure below 1 ohm and this is normal.

If your main power rail is present, next step is to check the presence of your 3.3V LDO to the EC from PU100 pin 17. There is a power sequence on pg 5 of the schematic to follow. Dell laptops can be very fussy with power adaptors too so make sure you are using a genuine one for troubleshooting purposes. This laptop can take power either from the DC jack or USB-C.