Chosen Solution
So, I got a ‘‘JVC LT-40E71(A)’’, when turning it on the standby button goes from red to blue like it should, everything is fine there. but the problem is that the logo only pops up sometimes, when it does the TV works fine,. 95% of the time the screen gets back-lit and just stays dark, whats the problem? I’ve been looking around for a psu but I would like to be sure that would fix it before I buy anything. Thanks in advance!
@vasso123 this could be a bad power board as well as a bad main board. rembmer that it is the main board that sends the signal to the power board. Your JVC is a bit tough to find schematics for, we’ll need to depend on your skills here. Go ahead and post some good pictures 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. Update (08/25/2018) Your power board TV3902-ZC02-01(C) is also use in also used in Haier 40D3500M Haier le40f3000w. That is just an FYI ;-). Check the voltages on COM4 on the power board. This would be great to measure when it works and when it is not. That would give us a good indication. Anyhow, check these values: CON4 Pin number Signal name 1 NC 2 GND 3 GND 4 +5V 5 POWER ON/OFF 6 +5VSTB 7 +5V 8 +5V 9 GND 10 GND 11 GND 12 +12V 13 +12V You can also measure these cicuits and see what values you get.
