Lenovo Legion 5 Pro 16ACH6H Water Damage

[Andreasbest]

Hello!
Today i received a Legion 5 pro with motherboard NM-D562 that suffered water damage, no power at all, no led, no fans, nothing.
I measure 20v on PQ5401 at pins 5, 6, 7 and 8 but 0v at 1, 2, 3 and 4.
Is this normal?
Thanks in advance!

Schematics and boardview-> https://www.badcaps.net/forum/troubl...95#post3254995

[Andreasbest]

bump

[Andreasbest]

I have no 3v. I think i get no voltage from PU5401 but not sure, i'm totally dumb in reading schematics.
If someone is willing to help i'm on the bench now and for the next hours. Thank you!

[Andreasbest]

Someone? Anyone?

[Andreasbest]

Bump

[Andreasbest]

None has the slightest idea?

[khaahk]

PU5401 gets its power via pd5401.
Voltages on pin 5, 6, 24, 28 of PU5401
Resistance to gnd on PR5401

[Andreasbest]

PU5401 gets its power via pd5401.
Voltages on pin 5, 6, 24, 28 of PU5401
Resistance to gnd on PR5401

Thank you for replying. To make sure i understand, you want to measure all these voltages and check ground resistance on PR5401 ?

[khaahk]

Yes

[Andreasbest]

Yes

Sorry for the delay, got a problem.
Here are the measurements:

PR5401 16Ω on both pins to GND

PU5401 voltages:
pin5 0v
pin6 2.68v
pin24 6v
pin28 30v

[Andreasbest]

*pin28 20v

[khaahk]

Measure resistance on pin 5 to gnd. If low ohms, remove 24780s and retest. If it changes to high value change 24780s. If not you might have problem with ec.
If originally pin5 to gnd measures high resistance - check pullup resistor re42, if it is ok then change 24780s anyways.

[Andreasbest]

Measure resistance on pin 5 to gnd. If low ohms, remove 24780s and retest. If it changes to high value change 24780s. If not you might have problem with ec.
If originally pin5 to gnd measures high resistance - check pullup resistor re42, if it is ok then change 24780s anyways.

450KΩ pin5 to GND
What is 24780s ?

[khaahk]

PU5401 = 24780S charger ic
Change it, most likely at fault.

[Andreasbest]

Since i must order it and wait 3 weeks for delivery is there any other measurement to take to verify it's faulty?
Also if the charger ic is faulty the motherboard should power up if i connect a charged battery, correct?

[khaahk]

I don't know no checks that can be done, it is ic-s internal fault. If mainboard has no further problems then it probably should work from battery.

[Andreasbest]

Still dead with fully charged battery. The problem must be somewhere else. Any ideas?

[mon2]

Test the resistance across the 2nd dcin mosfet.

source / drain
source / gate
gate / drain

often 2nd dcin mosfet is defective and takes down the 1st dcin mosfet since they share the gate pins.

no power to the board during these tests.

[Andreasbest]

Thank you but which one is the second dcin mosfet?

[mon2]

PQ5402