I have been diagnosing what is wrong with my Sony bravia KDL-46XBR4 and took the entire t-con board off of the panel to inspect it. I decided to create a solder bridge across the top of the fuse because it appeared that the fuse may be bad. When I did so and hooked it up there was a noticeable change. I took my ohm meter and decided to put the positive side (with it switched to 20 DC) and put it on the back of the t-con fuse. The meter read, 3, 6, 10, 12.2, 1, 3, 5, 10, 12.1, 0 and while it was spiking up and back down I could hear a strange clicking sound on the t-con itself. At every very quiet click the power would drop back to zero or close to it. I tested the power coming into the UB1 board from the GF1 board and it was a steady 12.4, which I thought was a good sign it is not a power supply issue.
Next I tested the UB1 board and the power on this board was surging in the same way peaking and dropping back down to zero. When I would disconnect the LVDS cables the surging stopped, on both of the boards so I tested the power on the FB1 board and it was steady as well. Any ideas????? Im thinking t-con is bad, but would like to know before I drop some big bones on it to find out its the UB1 board which is easy to find and cheap.