Dell Latitude E5590(La-f411p) water damaged

[estabilito]

Hi,
I have water damaged Dell Latitude E5590 around charging ic.
Laptop was dead but i replaced some components like capacitors, resistors, resoldered charger(intersil 9538h) but traces under PQ904 dual mosfet(AOE6936) was burnt.
I rebuilt traces and both mosfets(PQ904 and PQ905) and after all this work laptop started turning on.
I dont have battery so i want to be sure if laptop behaviour is normal before buying.
On PL902 i have weird voltage around 5Volts, on battery socket voltage looks normal - 13.5v.
Is this voltage on pl902 normal?

[pc_okay]

Hello,

Yes totally normal, it's a buck/boost converter.
This system can lower or raise the voltage.

To lower the 20v charger voltage to system voltage (battery voltage), IC chip send ultra fast pulses (to the gate of pq905) then 20v can pass or not to the coil. The average of 20v pulses give 13,5v (after passing throw coil and caps)

But your multimeter is is not fast enough to catch the pulses during the process (With an oscilloscope you Will see short séquence of 20v then 0v then 20v then 0v…

for more info look at this great video from Louis R:
https://m.youtube.com/watch?v=B5eWpRFC9Aw

[estabilito]

Perfect! Thank you so much for the anwser