Picture tubes and the brightening thereof

[RetroHacker]

I'm sure that this sort of question has been asked many times before, but I figured I'd ask anyway...

What are everyone's experiances with brightening/rejuvinating old picture tubes? I've got at least one set (a 23" black and white GE) with a dim tube, and others that probably have dim tubes, I'll find that out once I get them to work. I've heard many sorts of methods, the traditional and dreaded picture tube brightener, that goes on the back of the tube and boosts the filament voltage. I've heard about "zapping" the tube with a picture tube rejuvinator to brighten it up, and "cooking" the tube overnight on a tester. Adding turns to the flyback to increase the filament voltage also probably works, but seems more like a DIY brightener.

So, my question is, what have people had success with? I don't have a picture tube tester, but I could probably build something to supply a filament voltage to "cook" or "zap" a tube, but I would like to hear about other people's success stories, failure stories, and ideas. It seems that everyone has some method to making worn picture tubes bright again, and to tell you the truth, some seem more like witchcraft than anything, but I'm sure someone has gotten it to work. But how long do tubes typically last after brightening. I mean, I would imagine that just about anything is a temorary fix, but it's better than sitting in dark watching television...

-Ian

[compucat]

There are many methods that get results, none of them truly permanent. Before I got a rejuvenator (which only works on '50s and '60 tubes, it's an old one), I would connect the filament to a 12V power supply for maybe 20 minutes or so to bring the cathode back to life. It usually worked. Sometimes just using the set daily would be enough to bring a tired tube to normal brightness. Most times though, a dim tube means the cathode emissive material is just used up, time for a rebuild or replacement.

[Chad Hauris]

I have had success with wrapping wire around the core of the flyback to produce a boosted heater voltage and putting this to a DPDT switch mounted on the back of the set along with the regular heater voltage. This allows you to switch in the boosted voltage and back to regular...if the tube is starting to lose its reds, etc. but is not totally worn out you can switch in the higher voltage for a few minutes and rejuvenate it...the improvement often will last for a week or more before you have to rejuvenate it again.

With the switch, you are not over-stressing the tube from the boosted voltage continuously.

If the tube is just kind of lazy from non-use this can work too...this is only good for solid state sets as the extra filament winding will overload the tube type HO system.

On tube sets I have used boosted voltage say 8 or 9 volts from an external supply but it seems the tubes I tried this on were just too worn out to rejuvenate.

Yes I would also concur that on a set that hasn't been used for 30 or 40 years, just operating it for a while will often wake up that old CRT.

[jstout66]

I have had pretty good luck with a rejuvinator, but am unsure how long the results last. I used to help out in the "Used" store in my hometown, and would set up and sort throught the electronics section. The rejuvinator came in handy on some old XL100 consoles we'd get in, that had a dead gun. It was better to zap the tube and sell the set for $25.00 than pay the dump fee to haul it away. In my Uncles repair shop, he'd only use his rejuvinator as a last resort. Usually for a set that wasn't worth putting a new tube in. He hated brightners and NEVER used those......