The Zenith/LG tube debacle--ON PURPOSE?

[rca2000]

DO NOT forget....all of the 19 and 20 inch MINI-NECK tubes... They do NOT hold up well at ALL...and will not take rejuv much better than a Trinitron. Now--the 13" mini-necks...not bad..pretty long-life..I suspect it is because of those tiny gun structures inside of that thin neck...

ALSO..those 1st gen GE inline larger than 10" tubes for the mid-late 70's...the one with the big neck line a portacolor tube...I have seen a LOT of bad ones of those in the day...

And speaking of the Trinitron...not sure HOW they made them this way....but they just do NOT like to take rejuv...maybe for a few DAYS or so...then they look WORSE than before...

[rca2000]

Originally Posted by sampson159

those rca deltas would respond well to hit or two.the last deltas in the late 70s were pretty bad though.never saw a delta zenith that was unwatchable.saw many sylvania dark matrix that hit the skids prematurally.the first 25 inch zenith inlines were fairly good.i have two spares that are very good.the zenith crts from the 80s are ok,but nowhere near as good as the deltas.had a zenith 27 inch console from 1994 that had an orion crt.it was a replacement and it looked bad!tested good but was dim in the set.watchable but not really good.as i ve said before,sad to see this happen to the best manufacture of television

Perhaps the early demise of those Sylvania CRT's is why there seem to be so FEW...Sylvania color SS sets around today !! like you said...they were N OT long-lived. Looked GREAT when they WORKED...but was more on the lifespan of a 23EGP22 tube...

[rca2000]

Originally Posted by radiotvnut

I remember reading somewhere that the the factory where the tubes were made was not nearly as clean as it should have been and the contamination had a lot to do with these tubes failing.

I've worked on a few '90's Goldstar TV's that had the same crappy Zenith CRT's in them.

The main problem these tubes gave was intermittently shorting/arcing; which, would often take out the power supply and/or video output components. You could fix the chassis and the set might work for a minute, hour, day, week, or month and then the tube would arc and blow up everything that was replaced. The tubes also got weak way too quickly. In fact, I've seen brand new sets that looked like the tube was bad right out of the box. I can also tell you that the replacement tubes were no better. Generally, the only time the CRT was replaced was under warranty. Usually, when the tube failed out of warranty, the set was junked.

Starting in about '98, Zenith started using a mix of LG/Philips and RCA/Thomson bonded yoke CRT's; but, by that time, the damage had been done and in '99, LG took over Zenith totally. Personally, I've not seen a bad Philips or Thomson tube. I know of a couple of Zenith consoles from the early 2000's that are still in service. They contain non-Zenith CRT's and they still look fine.

I am keeping alive a 97 model 32" zenith console--with a GREAT tube. The cabinet is nice---and the elderly man does NOT want to get rid of it ? It makes me about $100 CLEAR..each time I work on it.. The last time it was just that little "pf cap" shorted and burned up off of the H-out. But I let him KNOW...if the tube WAS dying...I WOULD let him know....and for him to dump it. But that tube looks like NEW. I do NOT think the 32 and 35" Zenith tubes suffered like the smaller ones did.

[radiotvnut]

I don't think the 32" and 35" tubes were actually made by Zenith and that could be why they hold up so well. A friend had an early 31" Zenith digital system 3 (overpriced piece of junk) that had a Zenith-branded CRT in it; but, I never looked at it close enough to see if Zenith actually built the tube. Sometime in the mid '90's, it started going weak and I hit it with the rejuvenator. It lasted a few months and started going back down again.

Concerning Sony tubes, the earlier ones from the '70's and early '80's often won't rejuvenate at all and if they do, they won't stay up long. A few years ago, someone gave me a cosmetically mint condition 19" Sony from the early '80's (the varactor tuned model with the vertical row of buttons and a plastic woodgrain cabinet). The picture was green, with zero red and zero blue. On the tester, the green tested strong; but, the other two guns were totally dead and would not rejuvenate. I ended up junking the set. I've rejuvenated some of the later Sony tubes that held up for a little while; but, not as long as other tubes that I've hit.

Concerning the later small neck color CRT's, the local hospital had 20" Magnavox sets in all the rooms and these used that type of CRT. The local parts house always kept that CRT in stock because they were constantly replacing CRT's in those sets. I think some of those sets are still in service; but, the last I heard, they are no longer repairing them. When they fail, they are being replaced with flatscreens.

[andy]

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[radiotvnut]

It seems like the large screen Zenith B&W tubes from the '60's and '70's often got weak quickly. I think many of those tubes were actually made by Sylvania. I have a Zenith 14N22 B&W console from '69 and it's CRT is, fortunately, still very strong. I don't know if the tube in that set is a real Zenith tube or one sourced from somebody else. One day, I may open it and see what the EIA number is.

[mr_fixer]

Alright here is what I think happened to Zenith crt quality. many years ago when i first joined videokarma, "it was only Audiokarma back then". A forum poster noticed that zenith crt failure was cause by the aquadag "conductive" coating of the crt flaking off of the inside of the crt and being accelerated by static charges toward the the cathodes causing the hard shorts which killed power supplies.
About that same time period the was a documentary made about the closing of the zenith plant on melrose and there were audio interviews with former workers reminisensing about there days making crts. One of the employees commented that there were chemicals used in cleaning parts "CRT shells?" that were not allowed by the epa? osha? anymore. anyone knows coating processes are highly dependant on the prep and cleaning of the surfaces.
here is a link to the documentary called "Matter of Time- Zenith"
https://www.youtube.com/watch?v=6RSEIa3TZ6k
the comments from the former worker are at 5 min, 32 secs

[rca2000]

SO....basically the "greens " KILLED ZENITH? and the SHUTTLE? and who knows WHAT else ?!!

WHY...am I NOT surprised to learn this? Maybe...because up to THAT point...Zenith had GREAT CRT's and before THEN--(Chromacolor delta days) the VERY BEST CRT"s EVER made..So...SOMETHING had to change...

ANOTHER case of another "DISprovement" from the greens--to a used-to-be GREAT product !!!

[Jon A.]

Originally Posted by sampson159

those rca deltas would respond well to hit or two.the last deltas in the late 70s were pretty bad though.never saw a delta zenith that was unwatchable.saw many sylvania dark matrix that hit the skids prematurally.

My E48-2 Sylvania has its original dark matrix 25VFAP22 which responded very well to my Sencore's auto-restore. It's a high-hour set, lots of dirt inside when I got it and it has gone through at least two triplers.

[mr_fixer]

Originally Posted by rca2000

SO....basically the "greens " KILLED ZENITH? and the SHUTTLE? and who knows WHAT else ?!!

WHY...am I NOT surprised to learn this? Maybe...because up to THAT point...Zenith had GREAT CRT's and before THEN--(Chromacolor delta days) the VERY BEST CRT"s EVER made..So...SOMETHING had to change...

ANOTHER case of another "DISprovement" from the greens--to a used-to-be GREAT product !!!

Well maybe the engineering department didn't do a good job finding a substitute, and i'm sure managment had to cut costs to compete in the BPC era. Sony and others didn't seem to have a problem. and they made crt tubes for many years after the mid 90's

[andy]

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[MRX37]

I'd put the cutoff date for good Zenith CRT's at 1992, because I saw a Zenith with a 1992 manufacture date and its CRT was still good and strong.

And I had a 1998 Zenith A27a23w with a good CRT as well. Compare with a 1997 Hitachi that had a Zenith CRT, that CRT was awful.

[dieseljeep]

Originally Posted by radiotvnut

It seems like the large screen Zenith B&W tubes from the '60's and '70's often got weak quickly. I think many of those tubes were actually made by Sylvania. I have a Zenith 14N22 B&W console from '69 and it's CRT is, fortunately, still very strong. I don't know if the tube in that set is a real Zenith tube or one sourced from somebody else. One day, I may open it and see what the EIA number is.

I worked on a '73 model set with that chassis, that had a Clinton CRT. It had a good picture when it worked, but it had some kind of an intermittent. You had to tap on the neck, every so often to get it to work.

[DavGoodlin]

In the early 90s, Sony was making CRTS at the former VW plant in New Stanton, East of Pittsburgh. Between that and RCA's plant in Lancaster, many BPC sets lasted longer than ever. looking great