The contrast adjustment key (BSP) is located in the top right corner of the keyboard and functions directly on the console keypad from the main menu. The BSP key only works for contrast in the MAIN MENU. The LCD screen is sensitive to temperature and may turn pale or too dark with a change of ambient temperature or may have been reset. It is best to shield the LCD from direct sunlight when in hot environments. To adjust the contrast to a suitable level, press the key repeatedly in a loop. (Tip: This key also serves as the back space key when not in the main menu.)
Another cause for a dark screen could be that the 2.5Amp/250V fuse is blown and the SuperSting's RED light is constantly ON but the screen appears blank. The SuperSting™ will not turn OFF using the ON/OFF switch and the contrast key will not be operational. Replace the fuse to fix this issue.