I'm trying to diagnose my LEDTV's no power issue. For reference, the TV is not powering on, no standby lights or blink codes, no relay clicking, just nothing. The PS has 3.3v standby voltage and my bridge rectifier is reading in spec.
I'm following the standby voltage (3.3v) but the mainboard 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. If I use a jumper across "POWER ON" and "AC OFF DET", the 12v pins all get a solid 12.5v.
Testing continuity, I find the 3.3v arrives at the mainboard but when I test the correlating via to see voltage, I get nothing(0.002vdc). So there is continuity to the bottom of the pcb but nearly zero voltage. Shouldn't I be able to see 3.3v on the via?
Something I noticed though was when I unplugged the cable running between the power supply and the main board and ran a lead directly between the 3.3v pin socket on the cable to the male pin on the mb socket, I was able to read 3.3 volts on the via! It confuses me because my meter shows continuity through the cable to the via, but the voltage is getting lost somewhere. So, either the male or female socket/plug may be bad?
I can't figure out the next step without being able to follow the 3.3v rail to see why nothing is coming back from the mainboard. I want to eliminate the power supply completely. All the caps look fine, the fuse is fine, nothing appears damaged or shows signs of ever getting hot, no smells, nothing obvious.
I've looked at the service manual but it is a little difficult to follow. The procedural methodology seems like it should make sense but it has me frazzled.
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.
If you have any suggestions, I'd appreciate them. Should I be looking into the power supply further or does my assertion of the fault being at the mainboard seem accurate?
Here are a couple reference photos of the boards(not my photos but this is my exact board revision/model).
:blah:
I'm following the standby voltage (3.3v) but the mainboard 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. If I use a jumper across "POWER ON" and "AC OFF DET", the 12v pins all get a solid 12.5v.
Testing continuity, I find the 3.3v arrives at the mainboard but when I test the correlating via to see voltage, I get nothing(0.002vdc). So there is continuity to the bottom of the pcb but nearly zero voltage. Shouldn't I be able to see 3.3v on the via?
Something I noticed though was when I unplugged the cable running between the power supply and the main board and ran a lead directly between the 3.3v pin socket on the cable to the male pin on the mb socket, I was able to read 3.3 volts on the via! It confuses me because my meter shows continuity through the cable to the via, but the voltage is getting lost somewhere. So, either the male or female socket/plug may be bad?
I can't figure out the next step without being able to follow the 3.3v rail to see why nothing is coming back from the mainboard. I want to eliminate the power supply completely. All the caps look fine, the fuse is fine, nothing appears damaged or shows signs of ever getting hot, no smells, nothing obvious.
I've looked at the service manual but it is a little difficult to follow. The procedural methodology seems like it should make sense but it has me frazzled.
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.
If you have any suggestions, I'd appreciate them. Should I be looking into the power supply further or does my assertion of the fault being at the mainboard seem accurate?
Here are a couple reference photos of the boards(not my photos but this is my exact board revision/model).
:blah:
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