Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

[WhiteWolfHellas]

Hi everyone, this laptop once the PSU is inserted the power led lights up for a milisecond.

PQ206 has melted so the markings are unknown to me.
I need the schematic.
Can anyone help me get this motherboard fixed?
Thanks in advance.

[Techtiger]

Re: Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

Most probably, this MOSFET (PQ206) is one of the N-channel FETs used in the battery charging line. Can you send a clear picture of the module

[mcplslg123]

Re: Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

Yes, they are N channel mosfets. You need to replace both these mosfets alongwith charging IC and then finally check resistance to GND on charging coil.

[WhiteWolfHellas]

Re: Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

I forgot to mention that the 20V input goes to PQ201 (SM4377) but it has 0V in it's output so PQ202 (F2 VUA) is also with 0V in the input-output. Which of the two needs replacement? PQ201 or PQ202?

[Techtiger]

Re: Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

For the moment, leave it as is. Don't remove any components unless you are sure of what you are doing. The gates of PQ201 and PQ202 are connected to the battery charging IC pin ACDRV. To check the resistance, use a multimeter on continuity mode without power to PQ201 and PQ202.

[Techtiger]

Re: Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

Yes, they are N channel mosfets. You need to replace both these mosfets alongwith charging IC and then finally check resistance to GND on charging coil.

Replace the component @mcplslg123 requested

[mcplslg123]

Re: Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

I forgot to mention that the 20V input goes to PQ201 (SM4377) but it has 0V in it's output so PQ202 (F2 VUA) is also with 0V in the input-output. Which of the two needs replacement? PQ201 or PQ202?

No point troubleshooting before replacing the defective/burnt parts.

[WhiteWolfHellas]

Re: Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

Yes, they are N channel mosfets. You need to replace both these mosfets alongwith charging IC and then finally check resistance to GND on charging coil.

You mean I have to replace these 3 ICs? The right one is burned beyond recognition.

[WhiteWolfHellas]

Re: Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

Yes, they are N channel mosfets. You need to replace both these mosfets alongwith charging IC and then finally check resistance to GND on charging coil.

You mean I have to replace these 3 ICs? The right one is burned beyond recognition.

[Techtiger]

Re: Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

You need to replace 2 N-FETs, specifically the PQ205/6, as well as the charging IC on the left side of your pic

[WhiteWolfHellas]

Re: Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

You need to replace 2 N-FETs, specifically the PQ205/6, as well as the charging IC on the left side of your pic

Oh ok, PQ205 is an SM3308NSQA, I suppose PS206 is the same?

[mcplslg123]

Re: Lenovo S145 (GS440&GS540 NMC511 REV 1.0) No power

Oh ok, PQ205 is an SM3308NSQA, I suppose PS206 is the same?

Very likely same.