HWL 300 Super LED Tester 0-300V High-brightne Screen-free LCD TV Backlight Maintenance Testing Tools for Beads Lamp Strip Please use 19V voltage to detect the positive and negative electrodes when in doubt. Do not use 300V voltage to detect the positive and negative electrodes. 300V voltage may cause damage to the equipment. Three seconds plus or minus, high and low voltage switching Screen-free LCD TV maintenance testing lamp strip lamp 0-300V high-brightne screen-free version: Input Voltage: 85-265V Output Voltage: 0-300V Power 18W Automatic detection of output voltage and current Can test any size of LED backlight and lamp beads High brightne, no need to open the screen can judge the quality of the backlight.