|DV 7 Power In Section|
These units are totally different than the previous DV2xxx, DV6xxx, DV9xxx series, and the power indicator on the side gets power from the board not the charger. So if the power in is good, it will not give you any indication, because it draws 5v from the laptop and not the DC jack circuit board.
When checking the system I used a meter and checked the red wire (Line In POS+) and it had the 19v and the yellow was 0v. Moving to the next chip in the circuit I tested the SI4835 mosfet and it was dead shorted in both directions. So I took it out of circuit and tested it on the bench with meter- same thing. The mosfet was shorted. When it should allow current in one direction only, it was allowing in both directions and the unit would never power on. Without having the exact number available, I went to the manufacturers site (Siliconix)and Vishay to check the specs on the chip. This allowed me to use what was available, and not having to go out or wait for a replacement to come in. In this case it was a AO4407 which I keep on hand. Replacing the chip the unit powered on, and charged the battery properly.
Reminder: The site/blog is to assist TECHNICIANS. I cannot help individuals without any technical training or schooled in electronics because most of the problems covered are not user servicable.