Rca ctc-5

[miniman82]

Risk your flybacks at your own peril, I can only tell you that for me they have always run much cooler when the AC input voltage was set where the schematic shows- 117 AC. If you don't like the variac because it gets hot, buy an RCA isotap transformer. It has a switch instead, so you can set it and forget it.

Main reason high input voltage is bad is because it causes horizontal output cathode current to rise objectionably high, test and see for yourself. The more voltage goes into the set, the higher it will go. That's why flybacks run hotter why you plug it directly into the wall. More current=more heat, and if you're like me you don't like replacing flybacks from a preventable situation.