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This came in with water damage, put it in the ultrasonic cleaner and have a green/orange light but wont turn on. U7840 was burned so replaced it but still wont power on. I have 12V but no 3v or 5V
I am new to component level repair. What should I check next?
Kyle you must put your multimeter in resistance mode, then you put one wire in ground and the other one in pp3v42_g3h line (it doesnt matter where) and measure the resistance to ground of that line, measure it and post the value. Like if it were a resistor.
You are answering questions I didn't ask! I do not care what voltage is on PP3V42_G3H. What is the resistance to ground on that bus? You can measure anywhere on the board, at any point. PP3V42_G3H shows up everywhere.
Think of it like me asking for the temperature and weather in area code 10009.
I can measure the temperature outside my store
I can measure the temperature outside the school across the street.
I can measure the temperature at the grocery store next to the school.
It will be cloudy and raining, at around 47f in any of these locations.
That means that PP3V42_G3H is shorted.
So you will need to apply first 0.5V from a power supply in that line and check if anything is getting hot...nothing?ok 0.5V more, total= 1V to a maximum of 3 - 3.42 Volts to that line (pp3v42_g3h)
Something is wrong here. Are you in resistance mode? Are you measuring resistance WITHOUT power connected? You can't have 0 ohms of resistance to ground on a line if you also have 3.42v present on that same line.