22-09-2021, 02:33 PM
(This post was last modified: 22-09-2021, 02:35 PM by Mike Watterson.)
Lamp limiters are of most use on Valve TVs, and secondarily on series heater radios after you've replaced obviously bad caps etc. Not much use for an amp like this.
It's common for valve heater to be fed from the motor and HT is rectified mains. So live.
Separate motor and run it direct if using a limiter. But reform HT and electrolytics with a 30V current limited PSU ( a few mA) with valve out and no mains. Replace paper caps on anodes to anywhere. They can have metal or composite cases, not just waxed card. Reform and check cathode electrolytic by disconnecting cathode end; if it's leaky the bias is excessive. This circuit is so simple a limiter isn't needed if the parts are checked.
It's common for valve heater to be fed from the motor and HT is rectified mains. So live.
Separate motor and run it direct if using a limiter. But reform HT and electrolytics with a 30V current limited PSU ( a few mA) with valve out and no mains. Replace paper caps on anodes to anywhere. They can have metal or composite cases, not just waxed card. Reform and check cathode electrolytic by disconnecting cathode end; if it's leaky the bias is excessive. This circuit is so simple a limiter isn't needed if the parts are checked.
