About the lifespan of CRT"S

[rca2000]

[Bottom line: A CRT new in the box, with excellent vacuum, should stay as new forever. But one with poor seals (15GP22, and any metal/glass combination), or any CRT with less than excellent vacuum (Sony from the 80s/90s, Mitsubishi projection from 90s, etc) will deteriorate no matter what, but can be kept alive longer if the filaments are warm all the time.

Charles[/QUOTE]

You are SO right on the Mitsubishi CRT's in their Big Screens. I worked on one today, a 97 model or such,and the tubes are Shit. I mean, they work, but they have that "soft" look, that mits tubes are known for. whereas, my '94 RCA BS with hitachi tubes looks better than some new sets. I am sure that probably 85-90% of the tubes life is still there. This is NOT the exception, rahter the rule, where those RCA sets (and hitachis too) from the late '80's to late '90's are concerned. The tubes seem to be nearly bulletproof, and last and last and last. I have seen only a handful of bad ones, out of many hundreds of them I have worked on, compared to many bad mits. tubes. To me that is SAD, because Mits. was SUPPOSED to be superior to Thomson(RCA) but the tubes (and caps on the boards) sure arent!

I figure, that the Hitachi tubes must have well evaporated cathodes with a lot of VERY pure material, and a very good vacuum, whereas the MIts. tubes probably have a softer vacuum, with less material evaporated on it, and less pue too. (RCA direct-view tubes from the last 20 years or so are similar in this regard,of very high quality and durability, only recently have they switched to a "crappy" tube, to cut cost.)

[domfjbrown]

Originally Posted by rca2000

You are SO right on the Mitsubishi CRT's in their Big Screens. I worked on one today, a 97 model or such,and the tubes are Shit. I mean, they work, but they have that "soft" look, that mits tubes are known for.

I don't think this follows for British Mitsu sets; my parents' 1994 21incher still looks as bright and sharp today as it did then; it actually has better dynamic range than many Sony Trinitrons, although the "football" nature of the faceplate isn't as nice as the older Sony cilyndrical one...

[andy]

...

[domfjbrown]

Originally Posted by andy

I think he was talking about Mitsubishi projection CRTs. I've never had any problems with their direct view CRTs.

Aha - projection tellies. Forgive me for being blunt but, err, yuk! I've never seen a projection telly I can live with - as with older-format LCD screens, if you have nystagmus, all you see with one of those is fading, blur, and blooming...

I'd much rather have a small direct view telly than a large projection one

[JCFitz]

Quote:You are SO right on the Mitsubishi CRT's in their Big Screens. I worked on one today, a 97 model or such,and the tubes are Shit. I mean, they work, but they have that "soft" look, that mits tubes are known for. whereas, my '94 RCA BS with hitachi tubes looks better than some new sets. I am sure that probably 85-90% of the tubes life is still there. This is NOT the exception, rahter the rule, where those RCA sets (and hitachis too) from the late '80's to late '90's are concerned. The tubes seem to be nearly bulletproof, and last and last and last. I have seen only a handful of bad ones, out of many hundreds of them I have worked on, compared to many bad mits. tubes. To me that is SAD, because Mits. was SUPPOSED to be superior to Thomson(RCA) but the tubes (and caps on the boards) sure arent! :Quote

Mitsubishi seemed to go downhill in the 90's.I've replaced many a cap in both projection and directview sets.But I haven't seen that many bad CRTs in Mitsubishi like you have.I've seen some 80's sets that the CRTs were shot or going downhill in recent years.The worse problem they have now is leaking coolant fluid.This happens on Mitsubishis from 96' or newer.It leaks on the circuit boards and shorts them out.The worse is the newer sets from 1999 on up with double sided signal boards and surface mount ics and a lot of boards are NLA.The fluid damages the feedthroughs and the open ones must be traced out and jumpered.The older ones from the 80s were better apart from the yoke failures on the 1985 models.I saw one with the fold out mirror from 1981 being used everyday and still going a couple years back.My mom has a 1987 60" Mitsbishi projo still going strong.Gets a lot of hours use every day.It even has the original convergence STKs.I dunno why they'e still working.They never last this long.One of these days I guess I'll get a phone call about the convergence.Only had the HV bleeder block go out in 2000.I've seen tubes die when they sat for long periods of time.I had a GE 25" console from the late 70s(the one with the large neck inline tube)In the early 90s it was getting weak on me.Had to keep the contrast down to prevent smearing and blooming and it didn't track very well.Rather than taking it to the auction to get rid of it right away(when you could get somethiing for a console even if it didn't have perfect color.I took my weak picture tube but still playing tvs there.I took the good ones to the flea market.)I sat it in the garage for a month.When I plugged it in at the auction the emission had fell off so bad from sitting you could hardly see the picture.I had to crank the screens and drives just to get a passably bright mostly blue picture.Green and red were done for.It had green and red when I unplugged it in the house.