I have a Royal CMS 482 Plus and it didn't work when I first got it then a couple months later it would make this high pitch noise when I plugged it in and the display would show zero now it doesn't work at all
Peform a ram clear, and reprogram. Half system clear . key to prg position, unplug register, replug. If this does not work full system clear, you will loose your programs. key to pgm, unplug register, hold clear key down and replug in. If this does not solve problem possible board problems.