Toshiba Qosmio X755 Charging problem

[delphi_firebird]

Hello Guys,

I received Toshiba Qosmio X755 that has a charging problem and I'm stuck trying to figure out the problem.

- When battery is unplugged i works without any problem.
- When I plug in the battery after plugging in the charger, it works correctly and the battery is charging.
- When I plug in the charger after inserting the battery, it stops working. ( voltage dropped and consumed 8A, reaching the maximum capacity of my bench power supply for 5 seconds, and stop working after )

Can you help me diagnose the problem? I have attached the motherboard schematic for your reference.

Reminder: rules and organization of this section - https://www.badcaps.net/forum/showthread.php?t=117483

Link to schematic - https://www.badcaps.net/forum/showthread.php?t=124760

Thank you

[Techtiger]

Re: Toshiba Qosmio X755 Charging problem

check PQ208/209 with the battery inserted verify if the voltage is flowing from Drain to Source could you provide the voltage at the Gate /Source /Drain pin ? PQ201 with the battery inserted verify if the voltage is flowing from
Source to Drain provide the voltage CHG_B+? test for any short on these two P-channel FETs (PQ208/209) using the Diode mode on the multimeter Source, Drain, and Gate."

[delphi_firebird]

Re: Toshiba Qosmio X755 Charging problem

Hello ,

Thank you for your answer.

PQ208/209 are not shorted . with battery inserted Gate is 0 and 14,5V is flowing from Drain to source.

CHG_B+ is 14,5 V so BATT+ is flowing from the source to the drain on PQ201 (it is not shorted )

[Techtiger]

Re: Toshiba Qosmio X755 Charging problem

Now check PQ208/209 with the adapter (with out battery) inserted provide the voltage on Drain Gate pin ?

[mcplslg123]

Re: Toshiba Qosmio X755 Charging problem

Either of these 4 mosfets is very likely shorted or leaky.
PQ203/204/208/209. Check resistance of all these fets.

[delphi_firebird]

Re: Toshiba Qosmio X755 Charging problem

Hello Guys

Thank you @Techtiger

and Thank you @mcplslg123 , you were right the pq204 was not completely shorted but was leaky , i replaced it and the problem was solved .

You

[Techtiger]

Re: Toshiba Qosmio X755 Charging problem

Either of these 4 mosfets is very likely shorted or leaky.
PQ203/204/208/209. Check resistance of all these fets.

Well done mcplslg123@