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  #1  
Old 11-24-2018, 11:05 PM
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Old CRT booster just lost it's job today!

Hello All! last week i got a haul of CRT testers/rejuvenators from a old tv service shop. today i tried using one for the first time . the tv is a 59/60 admiral B&W 23 inch set. It had a booster on it for years before i got it and barely a viewable picture. I used a Sencore cr70 and the tube didn't even move the needle. I followed the instructions for the auto restore mode and now the emissions read up to the letter "d" in the word good and are steady when the life test button is pressed. Yay! why did i wait so many years to get a tube rejuvenator?
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Old 11-24-2018, 11:23 PM
old_coot88 old_coot88 is offline
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It'll be interesting to see how long the rejuv holds up. We learned early to never do rejuvs on customer sets, as they went flat again in a week or two.
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Old 11-24-2018, 11:35 PM
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the cr70 manual said that if the needle didn't drop by 25% when the life test button was depressed that it would be good for 12 months or more. I guess YMMV. the odd thing was there were no sparks or flashes in the crt neck like others have said occurs.
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Old 11-25-2018, 01:56 AM
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I had an RCA round color tube test VERY poorly, it was the one from my Zenith remote set I got last fall, the red was totally dead, barely moved the needle. I used my Sencore CR70, no results. I tried my B&K 467, still no results. Just for the heck of it, I tried my Beltron when I first got it, and BOOM. The tube tests like new again. Beltron FTW.
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Old 11-25-2018, 03:48 PM
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Quote:
Originally Posted by TUD1 View Post
I had an RCA round color tube test VERY poorly, it was the one from my Zenith remote set I got last fall, the red was totally dead, barely moved the needle. I used my Sencore CR70, no results. I tried my B&K 467, still no results. Just for the heck of it, I tried my Beltron when I first got it, and BOOM. The tube tests like new again. Beltron FTW.
The amount of wear and tear on my beltron cases leads me to think they were the ones most often used, but i like the charts provided with the cr70. I'll keep the cr70 and one of the beltrons and whatever isn't fixed by the sencore, will get the Beltron treatment.
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Old 11-26-2018, 09:47 AM
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Quote:
Originally Posted by mr_fixer View Post
The amount of wear and tear on my beltron cases leads me to think they were the ones most often used, but i like the charts provided with the cr70. I'll keep the cr70 and one of the beltrons and whatever isn't fixed by the sencore, will get the Beltron treatment.

I've heard stories form others about the rejuvenation capabilities of the Beltron device. I suspect the others were trying to avoid cathode stripping in the rejuvenation process by being kindler and gentler.

I have a B+K 467 that is not working at present. Many years ago I used a Sencore tester (don't recall which model) to rejuvenate a 21FJP22 roundie. That produced a great picture for several years of hard use, believe it or not. The set is still in our family, and the picture is not great but still watchable after letting the set warm up. It hardly ever gets used now, however.
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Old 11-26-2018, 06:19 PM
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Quote:
Originally Posted by mr_fixer View Post
the cr70 manual said that if the needle didn't drop by 25% when the life test button was depressed that it would be good for 12 months or more. I guess YMMV. the odd thing was there were no sparks or flashes in the crt neck like others have said occurs.
The auto-restore mode in a CR-70 will not cause a spark or flash. It is not the same as a basic rejuvinate like in the Beltron where a capacitor is charged up with several hundred volts and dischanged through the CRT cathode. THe idea is to blow off some of the cathode surface and expose fresh material. Problem is that there is only so much coating on the cathode. It's possible to zap off too much and be left with a dead CRT.

The auto restore mode cycles the filament hotter than usual to burn off contaminants. Three cycles is recommended and ideally you see the cathode current increase with each cycle.
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Old 11-26-2018, 09:27 PM
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The CRT currently in my CTC-21 was pulled from a CTC-38 that I intended to restore, but unfortunately got water damaged. It had a tired CRT and a burned up flyback, but once I zapped the CRT with the Beltron and put it in my CTC-21, it showed a nice bright picture. I wanted to save that 38 because it was all original, but the weather had other ideas.
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Old 11-28-2018, 05:03 PM
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The Heathkit IT-5320 uses a Beltron-style method that requires varying filament volts while monitoring current on the 300 vdc it uses to rejuv. In 40 years, it has never let me down or stripped a cathode. There are some tubes that were not restorable.

My BK 467 and 466 are in the junk pile, as they both need some repairs.
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Old 11-29-2018, 05:04 PM
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I suppose it would be pretty easy to modify just about any CRT tester to imitate a Beltron. After all there's not too much going on in one.
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Old 11-29-2018, 09:31 PM
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The Beltron is a very simple device, and mine is in very poor shape, but it's my favorite. It wins over my 467 and CR70.
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Old 12-01-2018, 03:01 AM
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Originally Posted by TUD1 View Post
The Beltron is a very simple device, and mine is in very poor shape, but it's my favorite. It wins over my 467 and CR70.
I agree, but i am thinking that crts were over-built back in the day and had more cathode coating than newer ones. That is why i like 2 crt tester/rejuvenators in my stable. I like to use the weaker one first "sencore cr70" for lesser crt's" and Beltrons when the weaker ones don't quite cut it. As i said before the Beltrons i own have seen more usage, which means they had better results back in the day. Remember that there are no new crt's available and we must do the best we can with what we have.
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Old 12-01-2018, 10:59 AM
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Quote:
Originally Posted by mr_fixer View Post
I agree, but i am thinking that crts were over-built back in the day and had more cathode coating than newer ones. That is why i like 2 crt tester/rejuvenators in my stable. I like to use the weaker one first "sencore cr70" for lesser crt's" and Beltrons when the weaker ones don't quite cut it. As i said before the Beltrons i own have seen more usage, which means they had better results back in the day. Remember that there are no new crt's available and we must do the best we can with what we have.
+1.
I have yet to put my money where my mouth is on this (I'm the Jack Benny of the test equipment market), but I agree best to start with the most gentle rejuve available and work your way up till you get results... I've seen the CR70 slowly and gently work miracles on tubes that did not move the needle on emissions, and I've seen and operated harsher testers that have ruined cathodes.

Best to shoot Godzilla with howitzers and conventional explosives before nuking the city.
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Old 12-03-2018, 04:42 PM
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Quote:
Originally Posted by Electronic M View Post
Best to shoot Godzilla with howitzers and conventional explosives before nuking the city.
A good way to put it. We always used clean & balance first & most times
went no further. After rejuve we would run it over night then let it sit off
a day before final adjs. Some jobs would last over a yr others just a month.

The main purpose of brighteners & rejuves for us was to get sets out
& paid for. If you just told them the CRT was bad they abandoned the
set & never paid an estimate. If you get it running much better "for now"
the set got picked up & we got paid. We also gave them a coupon tward
any new Zenith for part of the charges to be presented AFTER the best
deal was made. That made for tons of sales.

73 Zeno
LFOD !
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Old 12-04-2018, 10:20 AM
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Quote:
Originally Posted by mr_fixer View Post
That is why i like 2 crt tester/rejuvenators in my stable. I like to use the weaker one first "sencore cr70" for lesser crt's" and Beltrons when the weaker ones don't quite cut it.
The test equipment stable is a perfect analogy. You do not trust a workhorse like the B&K 440-445 to gently restore any CRT, though you have the adapter or gun-switch/socket adapter to do so. With only one meter, the 445 is a tad cumbersome to compare cutoff and emission while switching between guns. I do like the way it TESTS roundies and deltas because the scale is bigger and easier to log readings from.

I trust the 445 to test my delta gun color tubes but only the HK gets a whack at first cleaning (using 110Vac) only THEN rejuv-ing (using 300vDC) if cleaning fails to get some action.

While a "made-for-color" CR70 or 465 may work best restoring CRTs, testing them is best left to a period-correct device for what your testing.
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