Troubleshooting of Samsung np-r428 no power on

Troubleshooting of Samsung np-r428 no power on

C145 Short circuit leads to the lowering of linear 3V, resulting in no booting.The COMS battery has also been discharged.It can only be replaced.

[machine model]: Samsung np-r428.

version No.: ba41-01215a

The maintenance process of the computer is too old.Plug in DC power supply, the standby current is more than 180 Ma, and the standby current is high.switch did not react.
The common point VCC 19v was normal, but 3V 5V was not.Later, it was known that this machine produced 3V 5V VCC after switch.Touch the standby chip rt8205agqw high temperature seriously.Due to the lack of experience, the rt8205c was replaced without measurement.As a result, the fault remains unchanged.Measure p5.0v_STB was normal and p3.3v was measured_Micom is 1.8V abnormal.Measure p3.3v_Micom does not have Short circuit.Current heating test didn’t burn.Measure p3.3v again_Micom results are normal, 3.3V.Can switch, thought that fixed the result is not booting up.The current is 500mA, and all the basic VCC are available.Once again, touch the standby chip rt8205agqw or high temperature seriously, and guess it is Short circuit.Check drawing p3.3v_Where did micom go.The first place to go is the RTC circuit.

no power on ance drawing of Samsung npc441

Samsung np-r428 no power on maintenance drawing 2

Drawings and physical drawings are as above.After the d516 is removed, the standby chip is no longer high temperature.When measuring the third pin of d516, it was found that Short circuit, only 30.schematic to the ground showed p3.3v_Micom connects 2 resistors and 3 Capacitor.Two Capacitor were found nearby, and they were still the same after being disassembled.

Conclusion: c145 Short circuit causes linear 3V to be lowered, resulting in no booting.The COMS battery has also been discharged.It can only be replaced.

&nbs