Today lesson is about Samsung motherboard, platform is BA41-02206A
This model of Samsung is the most problematic motherboard, what is the problem with this motherboard? Laptop does not start!
First of all which, want to test input of DC connector,the main voltage enters to this connector then enters to inductor for filtering, from this line on motherboard then goes to MOSFETS.Then outputs from MOSFETS go to other components, BQ735, Battery charger controller which is connected to these N-Channel MOSFETs, the problem must be in this area.After connecting the adaptor, it seems the problem isn't visible but the problem is there because Amper is not working. And the LED green light does not turn on because 19V main voltage is not there.The main voltage should be there to start the motherboard.
First of all i check the input voltages DC connector pins; two of them are empty pins which are Ground/GND and those full pins are pulse, main voltage is 19V here and the output is normal too.Then I test the output of this Inductor. After that want to test the MOSFET, it's input ok! Then I test the output of the MOSFET too, yes, here is a problem, voltage is 0.835 there!The problem here may are;The controller/IC which controls the battery charger does not open the way to these MOSFETS and there will be problem or one of these MOSFET may have a problem. Disconnect the adaptor before testing MOSFETS pins, in second MOSFET, there is problem; have tested with buzzer test, Diode and resistance. From the diagnostic of the system i got to know that second output of the MOSFET has the problem and it needs alternative N-channel MOSFET. Put little bit FLUX paste before Soldering.
Always, test the MOSFET after removing on the board, in Buzzer test you can get to know exactly how it is! Choose alternative N-channel MOSFET which is similar to previous one; check its voltage, resistance and Amper. After replacement tested the MOSFET, it has 19v and LED light turns on, and power button has 3.3v also, the system turns on.
This model of Samsung is the most problematic motherboard, what is the problem with this motherboard? Laptop does not start!
First of all which, want to test input of DC connector,the main voltage enters to this connector then enters to inductor for filtering, from this line on motherboard then goes to MOSFETS.Then outputs from MOSFETS go to other components, BQ735, Battery charger controller which is connected to these N-Channel MOSFETs, the problem must be in this area.After connecting the adaptor, it seems the problem isn't visible but the problem is there because Amper is not working. And the LED green light does not turn on because 19V main voltage is not there.The main voltage should be there to start the motherboard.
First of all i check the input voltages DC connector pins; two of them are empty pins which are Ground/GND and those full pins are pulse, main voltage is 19V here and the output is normal too.Then I test the output of this Inductor. After that want to test the MOSFET, it's input ok! Then I test the output of the MOSFET too, yes, here is a problem, voltage is 0.835 there!The problem here may are;The controller/IC which controls the battery charger does not open the way to these MOSFETS and there will be problem or one of these MOSFET may have a problem. Disconnect the adaptor before testing MOSFETS pins, in second MOSFET, there is problem; have tested with buzzer test, Diode and resistance. From the diagnostic of the system i got to know that second output of the MOSFET has the problem and it needs alternative N-channel MOSFET. Put little bit FLUX paste before Soldering.
Always, test the MOSFET after removing on the board, in Buzzer test you can get to know exactly how it is! Choose alternative N-channel MOSFET which is similar to previous one; check its voltage, resistance and Amper. After replacement tested the MOSFET, it has 19v and LED light turns on, and power button has 3.3v also, the system turns on.