Chosen Solution
I was watching TV last night, and the picture suddenly went black but the audio remained working. The “flashlight test” shows the image IS on the screen – so I assume backlight is not working. Why? I took off back panel to have a look. I unplugged connection between power board and main board and turned the TV on – the backlights did NOT light. I powered down and then reconnected the main board. See images below for boards. The power connector going to the LED strips has the pins layout labeled as shown below, with voltages I measured: Pin label Volts 1 D1+ 209 2 D2+ 202 3 D3+ 192 4 NC 0 (no connection) 5 D1- 202 6 D2- 192 7 D3- 0 With no voltage on pin 7, does that indicate the problem is with the power board, or the LED strips? How does one differentiate/correctly diagnose between these two potential causes? Thank you, Kurt
Hi @probro968 , How did you take the measurements? Did you have the DMM connected between earth and the D+ve leads? The D-ve leads are the return path for the current. Did you measure the LED voltages with the LED power cable still connected to the power board or disconnected from the power board? Try measuring the voltages at the power board LED power cable connector point, with the LED power cable disconnected from the power board and check the voltage on all the D+ leads only. They all should be a high voltage as there is no current flowing through the LEDs. If this is the case then the problem is with the LED strips or the connection to the LED strips as the power board is trying to drive the voltage as high as possible in an attempt to turn on the LEDs Here’s a video that may help
