Color crt life

[JohnCT]

Regarding filament - yes, running at lower filament will extend life much the same as running lower brightness and contrast levels - lower beam current.

I discovered by simple observation that some RCA XL100s were having premature CRT failures about the 5 year mark. Not really bad, just soft. These chassis had a two position switch on the back for line voltage, and the filament in these sets were line AC sourced, not the flyback, so there was no regulation involved. The examples with weak tubes always had the switch in the low position (which would raise the filament). I don't recall if I the filament was above 6.3 nominal in the weak examples or below 6.3 in the examples that had long tube life. That was a long time ago..

Back in the late 70s, I was young, full of beans, and any little thing that would pop in my head would often become reality.

I had a 19" Zenith, and I built a small add-on circuit to the filament supply to the tube that lowered the filament voltage to the tube after it was running about 10 minutes. I did this with just a relay, 10W resistor, and a transistor/capacitor relay driver.

The tube was perfect the whole time I had it, but as someone commented earlier, these tubes were ridiculously long lived anyway, so who knows if it had any effect.

John