High-voltage variable resistor unit

A high-voltage variable resistor unit comprising:

• a variable resistance circuit board having a variable resistance circuit pattern provided on a front surface thereof;
• an insulating casing made of insulating resin and formed at one end thereof with an opening;
• said insulating casing being formed therein with a board receiving chamber for receiving said variable resistance circuit board therein and a capacitor receiving chamber;
• a fixed resistance circuit board provided on a front surface thereof with a fixed resistance circuit pattern and received in place in said insulating casing, said fixed resistance circuit pattern being electrically connected to said variable resistance circuit pattern;
• a capacitor arranged in said capacitor receiving chamber and connected to said variable resistance circuit pattern and fixed resistance circuit pattern;
• at least one slide arranged in a space defined between said variable resistance circuit board and an inner surface of a wall defining said board receiving chamber of said insulating casing and operated from an outside of said insulating casing;
• said insulating casing being mounted on a transformer casing of a fly-back transformer and charged therein with molding resin, which is cured to form a molding resin layer in which said fixed resistance circuit board and capacitor are embedded;
• and
• a lid member arranged for closing said board receiving chamber to prevent said molding resin from entering said board receiving chamber while keeping a front surface thereof facing a rear surface of said variable resistance circuit board;
• said fixed resistance circuit board being fixed on a rear surface of said lid member while keeping a rear surface thereof facing a rear surface of said lid member.