Dell Latitude 7410 no charge

[mon2]

Measure the voltage on pins 1, 2 and 6 on the replacement part at pq807.

[Andreasbest]

Measure the voltage on pins 1, 2 and 6 on the replacement part at pq807.

1 and 2 0v
6 ~0.5v-0,7v

[mon2]

Something is incorrect here.

If the gate voltage = 0v, this N-channel mosfet will be OFF. Then there must be a higher voltage on pin #6 unless the resistor on pin #6 is defective or not soldered properly.

Was the replacement part a known good donor part?

Earlier, there was a gate voltage but now it is 0v.

[Andreasbest]

Yes it came from a donor board with other fault (can't power on, amber LED only) BUT identifies the 19v correctly so i assume it was ok.
I resoldered all 6 pins, now i get 5v on pin#6 but pin#1 and #3 are still 0v
Do you want to resolder the old one or order replacements?
Or perhaps something else.

[mon2]

5v on pin #6 is expected. Did you not have a voltage on the gate pin on the first part?

[Andreasbest]

Well i don't remember, if i reported 5v then i should have measured 5v.
Do you want to solder the old one back and see if i get voltages?

[mon2]

Confirm the voltage to ground on each side of resistor @ PR822.

[Andreasbest]

No idea where the PR822 is, still searching
Meanwhile PR811 has 5v on one side and 0.7v on the other side that is connected to pin#6 of PQ807.

[Andreasbest]

Rear side of PQ800 area too.

[mon2]

Remove all power. Meter in resistance mode. One meter probe on pin # 6 of the dual mosfet. Other meter probe on pin #4 of the mosfet @ PQ800. What is the resistance? We are testing if PR811 is actually soldered and in the circuit or not.

[Andreasbest]

I get 50K this way.
Meanwhile found a Russian forum with the boardview but i can't pay with european cards due to sanctions

[Andreasbest]

Look what I noticed on PQ801
There is short between Gate and Source

[Andreasbest]

I cleaned the short but still same voltages.

[mon2]

Test PQ801 for defects since it was shorted.

[Andreasbest]

Source Gate 175K
Gate Drain 6M
Source Drain 0.8M

[mon2]

175k to me is low. Replace this mosfet.

[Andreasbest]

On the donor board is 200k
It's confirmed really low?
If it is then perhaps this is the fault on the donor too.

[mon2]

Test if the mosfet is low after removal from the board. Yes, 200k ohms is low but may be due to other parts on this board.