Lenovo ThinkBook Gen 2

[shybear]

hi,
This laptop doesn't power / charge battery next a bit of water entered from rear causing a relly little oxidation (around 10 x 15 mm) near PU5401.

Mainboard p/n is 5B21F20745.

There isn't any sign of overheating and discrete components near the oxidation (capacitors and resistances) are fine.

I've carefully cleanded and removed oxide but as attached picture of oxide damaged area looks like a missed resistance.

I was looking for a boardview or schematic of mainboard without any success, but when power supply is plugged in I can reach a 12V near battery and also a 5V.

Fuses are good.

Without any scheme I tried to put a working resistance of the same value of the near one (100K) with any success.

I need a scheme or a boradview to try to repair.

Ale

[mcplslg123]

Mention clearly the topside marking of IC and try to locate another schematic with same IC or its datasheet. That way you can get an idea about the value of resistor used by tracing pin number of ic to which the resistor is connected.

[shybear]

As attached picture I think that this IC is TPS51396A 4.5-V to 24-V, 8-A Synchronous Step-Down Voltage Regulator with ULQ.
Reistor is connected to pin12 this is "Enable pin of buck converter."
EN pin is a digital input pin, decides turn on or off buck converter. Internal pull down current to disable converter if leave this pin open.
I'll try to find a schematic with IC then.

[mcplslg123]

May help you

[shybear]

hi,
thnks for your effort! I'm looking at least of a boardview / scheme of this mainboard. If you looks 100k jpg there is an other resistor and its 100k. Anyway I think should I find Vin if laptop is off? Because I can find 12V n the 2 capacitors on the right side of resistors and also on other two other capcitors junst under pin 1 of ic. This happen if I attach power keeping disconneted battery. If I plug battery voltage rise to 14V.