Lenovo t495 dont switch from charger to battery

[Lcd22]

Hi everybody! This laptop eat my days in the last week. Initial i buyed a new battery, thinking is a battery issues but is not. The laptop charge fine, turn on fine when is plugged but when unplugg is dead. I think is a mosfet or chip who need to do the switch, but i cant identify him, and for that i need community help, thanks in advance! The mb is FA495-NM-C131-REV-1.0

[mon2]

Review PQ18 and PQ103 mosfets. Remove all power. Meter in resistance mode. Measure the resistance across this mosfet.

Check:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Testing for a low resistance. Each resistance should be hundreds of k ohms or higher for a normal mosfet.

Post each measurement. No power to the board during these tests.

[Lcd22]

I verified, i haved low resistance between source and gate of pq103. After desoldered it, i have low resistance between source and gate of pq18. I changed pq103 with another mosfet. The laptop power led flickering orange/white and dont start with battery connected. After disconnect battery, turned on plugged in. It s possible to both of them be faulty?

[mon2]

Test the removed mosfets on your work table. Are they still with the low resistance measurement? The in-circuit resistance may be different than out of circuit resistance. Also review PQ102 but note that this is a dual mosfet in a single package but testing method is the same.

Full details on this issue are posted here:

https://www.badcaps.net/forum/troubl...arging-circuit