CRT Heaters
 

Are the heaters supposed to glow when the set is off? I just noticed it while working on the 25EC58 chassis. It would probably explain why the picture comes up so quickly when turned on. Still, seems like it would be a bad thing causing wear.

I don't know anything about that particular chassis, but I assume that your set has the instant-on feature. Probably best to disable that if possible.

On your Avanti? Yes... most of the Zenith horizontal chassis had instant on. The Chromacolor tube, for the most part, is bullet-proof. You'll get a lot of opinions, and mine will be in the minority, but instant on isn't as bad as most tend to believe.
Think of it this way.... have you ever seen those shows on History channel or PBS on old Edison light bulbs, that have been on continuously for like 90 years? They still work because there isn't the constant cycle of on/off cool down. It's much the same way with a picture tube. I myself think it's better for the tube. I WILL back-peddle a bit, and say I don't like instant-on in a tube chassis set. I think the heat build up isn't good for the chassis, so on those... if it has a "vacation" switch, I turn em off.
I have a 1975 Sony Trinitron, with instant on. It see's little use now, but has been plugged in for like 30+ years, and the tube is fine, and Trinitron tubes weren't as long lasting as a Chromacolor. So there you have it... my 2 cents worth.

Hmm, perhaps the Chromacolor tube is one of the few, if not the only CRT that leaving the heaters lit on wouldn't harm. I heard tell of an old Sharp set from around '72 whose CRT was killed by instant-on. It hadn't seen much use at all.

Great information. My main concern was I had another issue in need of fixing. So now my only issue is getting the thermistor replaced so my degauss works again and I can do the darn purity.

Thanks, all!

Yep, the Avanti. As long as the glow isn't from an electrical issue, I'm good with it. Don't know how long out of it's 39 year life it's been plugged in, but the CRT didn't show any issues on the tester.

Your set is instant on & the glow is normal. If you watch
the filament when you turn it on you will see it get brighter.
Zenith also used instant on in the early upright ( 19EC45 etc)
chassis also & a few B&W's, the 12" & 16" hybrids etal.
Now I will generate some hate mail.
Instant on in a solid state set is harmless & probably beneficial.
Instant on in an all tube set ESPECIALY compactron sets
is most probably destructive.
Go ahead, let me have it............

BTW was Westinghouse the first instant on set? As a kid I
remember a comercial about it. It showed a 19" B&W with a
sun screen turn on in 2 seconds. Big deal then.

73 Zeno:smoke:

Sounds logical. Probably cuts down on the flexing of any PCBs from heating/cooling cycles, thus cutting down on cracked solder joints.

weigh the crt.zeniths tubes and some rcas are actually heavier.quite a bit!never saw a bad zenith 25v crt.even when weak,still made a good picture.a heavy rca tube could be blasted over and over.had several that i would hit on an annual basis.after 1980,it all went downhill.i worked in the business partime until 1995.repairs were drying up and it became the disposable society.why repair,just buy new