Chosen Solution
I opened up and tested the standby voltage at connector but there is no printed voltage. In standby mode I only see .08 volts but when I press the power button I then show 3.8v. Isn’t there supposed to be 3.3v or 5v while in standby mode with red light on? All the YT videos I watched about checking standby voltage implied this should be the case. So then what should happen to the standby voltage when the power is turned on? I have no bulging capacitors and I checked them in circuit with an ESR meter, so far none of them are showing signs of being bad. I understand I may have to remove some components to thoroughly check them. I checked the bridge rectifier powered off and on and it seems good although the DC voltage is 114v. Is that too low? I saw many videos where it was around 160v. I checked the LED backlight line from the power supply board when powered on and there is no voltage so it shouldn’t be my LED strips or circuit. The standby light does blink six times before going off when power button is pushed. Power board is part number 193287 and mainboard is 194580. I found a kit on Shopjimmy for all three boards including the T con but of course the idea is to become a better troubleshooter and find the bad parts before throwing in the towel.
Markus it does sound like a PSU issue due to the standby voltage. Since schematics and manuals are not easily found for your TV, you would need to post some good images of your boards with your question. That way we can see what you see. Use this guide Adding images to an existing question for that. Do not forget to check the main board properly as well. After all, it is that board which turns on the power supply. Update (09/30/2018) Markus the voltage on the rectifier sounds about right. There are a few places where the DC voltage gets boosted once the TV turns on but the recitifier sounds normal. The standby voltage seems to be to low. You are right, the power supply provides the standby volaage to the main board. The main board receives signal from the power switch or remote etc. to turn on and “sends” signal to the PSU to turn backlight on etc. Of course, no schematic is available for your model. I wonder if you could try to start it by pulling SW (same as Pwr On on other make?) to ground with a 1K resistor. I do have the schematic for the power supply. See if that will help to further diagnose Schematic Prints
I ended up ruining my PS board and had to replace it (even more embarrassing since it’s now looking like I never had a bad board in the TV) but I just went ahead and got the three board set from ShopJimmy to be safe. I did the flashlight test again to verify a signal after I had the same symptoms after replacing all three boards and sure enough there is a signal there. I recall doing this test before but I must have not been thorough, now I’ll never know whether I even had any bad boards. This set doesn’t have a separate LED driver board and I’ve replaced all three boards, besides the fact there is a signal there when using the flashlight means it must be an issue with the LED strips, correct? Or is it possible the new PS board isn’t putting out the voltage for them because when I check for voltage at the LED connector I don’t see any. Shouldn’t there be over 100v DC to power the LEDs at that point where the arrow is pointing in the picture? My question is: Does the software run a test while the standby light is blinking after powering on the TV to make sure certain conditions are right before sending the voltage to the LED strips? I don’t want to do all of that extra work to get to the LED strips if I should be checking/changing the PS board again Thanks.
I have the same problem with no STBY voltage even though the red light is on when plugged in. The schematic shows STBY as coming in to the base of a signal transistor…..? This would imply the incoming signal would activate the opto isolator…etc..? Does this signal come from the main logic board….is it included in the 12v or 16v lines provided to the main board and reduced to 3.3v there and sent back?
