If the LCD has passed the Built-In Self Test (BIST) but there is still a video problem, which component should be checked first?

When the LCD has successfully passed the Built-In Self Test (BIST), it indicates that the display circuitry and the panel itself are functioning correctly. This suggests that the issue is likely related to the signal pathway rather than the display hardware. Therefore, checking the LCD cable first is the logical step.

The LCD cable is responsible for transmitting the video signal from the system board to the LCD screen. If there is a problem with this cable, such as damage or a poor connection, it can lead to video issues even when the BIST has passed. By inspecting the LCD cable, you can identify whether a faulty connection or a damaged cable is causing the video problem.

In contrast, while components like the inverter board, system board, and power supply are essential for the operation of an LCD display, their involvement would generally not be the first hypothesis if the BIST is passed. The inverter board relates to the backlight operation; the system board processes and sends data to the display, and the power supply provides the necessary electrical power. However, since the screen has already shown it can function during the BIST, examining the LCD cable for physical damage or disconnection is the most logical initial step in troubleshooting the video problem.