Old CCFL bulbs require higher voltage to "strike," which can trip the over-voltage protection.
Note: Pin numbers above are referenced from the standard SOIC-20 package versions of the LX1692 (such as LX1692E). Always confirm the pinout against the specific datasheet for your chip version. lx1692 protection pin
Before we focus on the pin itself, let us establish context. The LX1692 is a high-efficiency, current-fed push-pull inverter controller. Its primary job is to convert a DC voltage (typically 5V to 24V) into a high-frequency AC waveform to drive CCFL tubes. These tubes provide the backlight for older LCD monitors, TVs, and laptops. Old CCFL bulbs require higher voltage to "strike,"
Small blue high-voltage capacitors on the output often fail and leak current to ground. lx1692 protection pin