Chosen Solution
I have the VIZIO D50U-D1 and anytime I power off and on the the TV the vizio logo comes up then everything goes black. If i use a flash light I can see images. Also I have noticed that tv is restarting itself. I have tried some diagnostics, verifiying I am getting 3V at the ON/OFF pin of the power supply board. I have also measured the voltage going to the driver board and the voltage going to the led strips. The voltage supplied to the driver board stays constant, I believe it was 24V. Monitoring the voltage going to the LED strips I was getting 35V when the backlights worked, but the voltage dropped as the backlights fades out. I replaced the driver board with no luck. Any suggestions as far as should I look at the LED backlights? Or is there any other way to check if the main board is functioning correctly?
I have attached images of the power supply, main board, and led driver board. I drew red boxes around the pins I was measuring the ~35V. But my main question is what could be the problem that the backlights work when I power the tv on, but after the vizio logo they stop working?
Allen Locke Since you can see the screen with a flashlight, your main board is working since you do get the signal to the screen. You replaced the driver board already, we assume that it is okay. The only thing that does not quite fit the bill is that your TV is turning itself off. That is uncommon for a backlight array failure and would most likely be a PSU issue or a main board issue. You would have to check the voltage on BLOn contact to see if your main board send the signal to the PSU to turn the backlight on. If your boards are all working the way they are meant to do, this could (most likely is) failed backlight LED strips. Use this video to replace yours. Would be so much easier if Vizio would supply Service manuals or at least schematics….
