1、High speed single-chip microcomputer is used for voltage sampling test, and LED lamp is driven to display voltage (by no means other products on the market use purchased voltmeter heads, which are installed separately) to achieve board card integration and reduce defective rate (because the current is constant, only the voltage display function is used.) 2、0-300V adaptive voltage, suitable for most series and parallel lamp bead tests. During the test, the gradual startup mode is adopted, the voltage is automatically adapted, the current is gradually increased, and the lamp beads will not burn, and the normal brightness can be achieved in three to five seconds. The positive and negative poles of the lamp bar and lamp bead are connected inversely, without burning the lamp bar and lamp bead. 3、Digital display of real-time voltage output, with adjustable voltage, the voltage value can be self calibrated. The digital meter adopts green light-emitting tube. 00 indicates short circuit and 300V indicates open circuit. The display voltage of each group of LED light bars of the same LCD TV shall be the same.