Yamaha DGX300 make loud hum when turned on and does not work.
Most of the time when I turn it on, I get a quick blast of static and then a continuous loud hum. Occasionally if I keep trying I don' get that and it works OK except for very low volume. I originally thought 60 cycle hum from some interference but tried on other circuits away from other devices with no change, except still once in a while turned on with no problem. I like the size and key style of this keyboard and don't want to scrap it. Advice and access to service manual much appreciated.