I'm trying to diagnose my LEDTV mainboard and am following the standby voltage (3.3). It is evidently not sending any signal back to my powersupply to enable the rest of the pins because the rest of my 12v rails don't have any power unless I use a jumper across "POWER ON" and "AC OFF DET", at which point the 12v pins all get a solid 12.5v.
Testing continuity, I find the 3.3v arrives at the mainboard and reaches the bottom of the PCB but when I test the via to see voltage, I get nothing(well 0.002). So there is continuity to the bottom but nearly zero voltage. Shouldn't I be able to see 3.3 on the via?
For reference, the TV is not powering on, no standby lights, no clicking, just nothing. The PS has 3.3v standby voltage and my bridge rectifier is reading in spec but I can't figure out the next step without being able to follow the 3.3 rail to see why nothing is coming back from the mainboard. All the caps look fine, the fuse is fine, nothing appears damaged or shows signs of ever getting hot, no smells, nothing obvious. I'm trying learn something here and prevent adding to the floating garbage island. I can't see any reason why this piece of technology should be wasted.
BTW it is a Sony KDL-55W802A. I'd appreciate any input!