Fusistor Replacement - RCA 14PD8054

[VintagePC]

Originally Posted by mbear2k

Sounds good - thanks for the info. The rating for the set is 1.1 amp, 125 watts at 117 volts. But I will do the electrolytics, then do a current test and see where I am with modern AC voltage. I'm guessing either a 2 to 2.5 amp fuse?

That sounds like it should be good - If you can get a peak current reading at turn-on, you can use that to better determine the safety margin you need - If it's too much larger you might want to up the wattage and resistance of the resistor a little bit - It's generally agreed that the the softer this old gear warms up, the better; many people have made modifications so that their tube filaments don't get a power-on current spike, like DaveWM is suggesting.

You'd probably want to be a bit more careful with a SS rectifier, but with a tube, the HV won't appear until it's good and warm along with the others, so a slightly slower start has no ill effects.

I probably wouldn't worry too much about which of those to get - short conditions usually cause current draw in excess of that 0.5A difference, so you'd be protected either way... but if you already have them on hand, then I'd go with the 2 and replace it with a 2.5 if it blows under normal operation.