I have seen this problem in 2 of the model UN55B8500 tv's. The television will not turn on and a clicking sound can be heard from the back of the unit. In both TV's I repaired, the problem was not the power supply or the main circuit board. The problem was the 2 small function boards mounted in the frame. One for on/off and the other for menu, sound, and channel up or down. These boards are held in place by a non hardening glue. It appears that if the area on the frame around these boards is compressed when lifting the tv, the buttons seem to stick or operate by themselves. If a button sticks, this can prevent the tv from turning on, and it makes the relay clicking sound. One tv would display the menu in the middle of a program with no one pushing a button. Both tv's were repaired by simply removing the 2 boards, removing excesss glue and reinstalling the same boards.
Follow up on above post: One of the TV's has the on/ off problem again two months after the repair. I changed the touch boards with new boards, but that did not fix the problem. I found that laying the TV flat and disconnecting the plugs between the circuit boards and then reconnecting could make the problem go away. After reconnectiong all the connectors, I could not make the problem appear again, so I assembled the TV, placed it in the upright position and kept checking for a few days. After approximately 5 days, the problem came back. The TV would not turn on. The blue light was on, and I could not turn the TV off. I disconnected the power and tried again. No luck. So I tapped the TV on the back a few times with my open hand, not enough to dent the cover, and it worked when I did the remote. This has happened 2 times since I tapped it on the back the first time , and each time after a few light taps, it works. Loose connection appears to be the problem. The cable that runs from the power supply board to the main board carries the signal to turn on the TV, and it hangs down when the TV is upright. It looks like some of the wires have tension on them. I have not fixed the problem yet, but if I can bring it on with the tapping a few more times, I will be checking the solder connections on the plugs on the boards and support that cable.
Follow up on above post: One of the TV's has the on/ off problem again two months after the repair. I changed the touch boards with new boards, but that did not fix the problem. I found that laying the TV flat and disconnecting the plugs between the circuit boards and then reconnecting could make the problem go away. After reconnectiong all the connectors, I could not make the problem appear again, so I assembled the TV, placed it in the upright position and kept checking for a few days. After approximately 5 days, the problem came back. The TV would not turn on. The blue light was on, and I could not turn the TV off. I disconnected the power and tried again. No luck. So I tapped the TV on the back a few times with my open hand, not enough to dent the cover, and it worked when I did the remote. This has happened 2 times since I tapped it on the back the first time , and each time after a few light taps, it works. Loose connection appears to be the problem. The cable that runs from the power supply board to the main board carries the signal to turn on the TV, and it hangs down when the TV is upright. It looks like some of the wires have tension on them. I have not fixed the problem yet, but if I can bring it on with the tapping a few more times, I will be checking the solder connections on the plugs on the boards and support that cable.
