820-2101 Main power rail checks and troubleshooting poweron
I have a logic board in a personal computer. This is my first experience in this type of work. I get green light on the charger adapter, battery removed cause its dead, and both fans spin. No startup sound or lcd or keyboard lightup. The front button light comes on and power button turns fans on and off and fans will stay running which makes me think the machine is running but i don't have anyway to tell. Oh there's no video through external dvi connection either.
I went through and tested the main power rails. The G3H rails that I tested are PPBUS_G3H has 12.6V, PPDCIN_G3H has 16v not 18.5v which I think should still be ok. PP3V42_G3H has 3.4v.
Next I went to 5V rails. PP5V_S5 has 5v, then get stuck on PP5V_S3. All the points I'm checking at has 0v (C5850, L5850, U5850, C4740) I am definitely out of my league with understanding how this line is generated. I do have boardview and schematics. Unfortunately, this is my first time. So any pointers that could give me an idea on what to check next would be much appreciated. Hopefully this is the only problem and there isn't other stuff like nvidia chip issues.
Is this a good question?