Chosen Solution
I have a Samsung TV (Model # UN40JU6500F) that has sound but a black screen. At first I thought it was the LED backlights so I changed those out. This didn’t solve the problem. When I held a flashlight up to the screen (while the TV is supposed to show a picture) I didn’t see a faint picture either. I think my issue is either the bus that the LED light strips plug into, the power supply, or the screen itself. How can I narrow down the options?
Hi @toastertom With the TV on but no image check if there is 12V on both sides of the fuse F200 on the tcon board. If not given that there is also no backlights its looking like the mainboard. If the fuse is blown then more likely it is the tcon board
click on image to enlarge
If you do not see any video with a flashlight then it isn’t a backlight problem, it is a video problem. It is more likely a TCON board or possibly the main board supplying video to the TCON board. TCON boards are high power devices so they are the more likely to fail.
@toastertom Samsung never published any information regarding the POST blink codes. 5 blinks are commonly caused by a bad power board. I would suggest that you start with disconnecting the main board from the power board and see if that turns your backlight on. If it does, you can be reasonably assured that this is not your power board. Of course, you can also measure the voltages going from the power board to the backlight strips and see what that voltage is. Check the diodes on the power supply. Make sure those show the proper values. Also, there should be two LED’s on your T-con board. If both are off your T-con board has issues with the DC supply. Once you checked all of these you can then deduct which board has failed. My first suspect is the main board as well. Let us know what you find.
