Is there a difference between NTSC and PAL CRT tubes? - Page 1
Forum section: electronics / projects

author: TinkeringTomas
author_rank: Newbie
timestamp: March 20, 2023, 09:32:49 pm
content: Hi!Are there any CRT TV aficionado here who can tell me if there is a difference between NTSC and PAL tubes? I know the shadowmask doesn't usually line up with scanlines and neither does it align with the "pixels" horizontally, so I would guess the tubes are the same. But are they?I'm asking because I may be repairing an NTSC (Japanese) CRT TV and may need to replace the tube if I'm unlucky. As I live in Europe, getting an NTSC TV as a donor may prove expensive. It would be nice if I could replace it with one from a PAL device.Thanks!(I sure hope this is the right place to ask. I can't find any other place on the forum to put it. Repair maybe?)

author: Benta
author_rank: Super Contributor
timestamp: March 20, 2023, 10:15:39 pm
content: No basic difference, shadow mask etc. would be the same.The only potential difference could be the vertical deflection coils due to the 25/30 Hz.

author: Benta
author_rank: Super Contributor
timestamp: March 20, 2023, 10:51:17 pm
content: I think you're confusing the (in)famous NTSC "Hue" control with phosphors. I see no reason for using different reds.

author: wasedadoc
author_rank: Super Contributor
timestamp: March 20, 2023, 10:54:14 pm
content: Quote from: Benta on March 20, 2023, 10:51:17 pmNo I am not. Read the colorimetry sections ofhttps://en.wikipedia.org/wiki/NTSCandhttps://en.wikipedia.org/wiki/PAL

author: Benta
author_rank: Super Contributor
timestamp: March 21, 2023, 12:09:12 am
content: Strange how your posts disappear. Trolling much?

author: vk6zgo
author_rank: Super Contributor
timestamp: March 21, 2023, 02:40:19 am
content: Quote from: TinkeringTomas on March 20, 2023, 09:32:49 pmNo the tubes should be exactly the same.Iwasconsidering the possibility of different heater voltages allowing for series string heaters differing in NA & EU, but most of the surviving colour TVs are solid state, with the CRT heaters supplied from an overwind on the Horizontal output transformer.

author: TinkeringTomas
author_rank: Newbie
timestamp: March 21, 2023, 05:49:50 pm
content: Awesome! Thanks all! It's weird that there is no way to find this information anywhere (or it's just me).I hope I don't have to do a tube swap, but just in case I've already been looking to salvage some locally. I expect the availability to keep going down the following years. Who in their right mind would still produce new ones? Would be a fun Kickstarter though, but probably not economically viable.

author: coppice
author_rank: Super Contributor
timestamp: March 21, 2023, 07:33:58 pm
content: Near the end of the life of CRT TVs a huge number were multi-standard, and would accept almost any TV signal and display it correctly. 525 line or 625 line. 50Hz or 60Hz. PAL, NTSC or some variants of SECAM. It made no difference what came in, a perfectly good picture was displayed.

author: SL4P
author_rank: Super Contributor
timestamp: March 21, 2023, 11:30:27 pm
content: I believe there IS a difference between northern hemisphere and southern hemisphere tubes.Based on their manufactured convergence and degaussing with respect tho the earths magnetic fields.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 22, 2023, 01:43:06 am
content: Quote from: SL4P on March 21, 2023, 11:30:27 pmI've never been sure whether this is so, or if it is an urban myth.If it is true, it probably is only valid for delta gun tubes.Trinitrons & their clones have a lot less ironmongery inside.In any case, CRT TVs degauss every time they are turned on, & it works well.If you leave 27 inch Sonys close to large magnets like those on TV Studio floor monitor speakers, the purity suffers.I was getting called on to degauss them regularly, until I realised they were being left on 24/7.Making it my mission to stroll through the studio & turn them off soon reduced my manual degaussing callouts to zero.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 22, 2023, 01:57:15 am
content: Quote from: TinkeringTomas on March 21, 2023, 05:49:50 pmA bit more I hadn't added.Colour tubes in good condition are quite capable of being adjusted to Illuminants "C" for NTSC, or "D" for PAL/SECAM.The only places anyone really cared in the old days was at TV production & transmission facilities.Many "domestic style" TVs came with default Illuminant "C", & if used in a TV Studio had to be readjusted to "D" to match the dedicated Broadcast equipment in countries using the latter standard.If tubes are "getting on in years", it may be difficult to set to either standard, so a compromise which wasn't too jarring to the eye was often used for domestic TVs.

author: bidrohini1
author_rank: Contributor
timestamp: March 22, 2023, 08:52:08 am
content: This may give some info too:https://www.diffen.com/difference/NTSC_vs_PAL

author: coppice
author_rank: Super Contributor
timestamp: March 22, 2023, 02:48:37 pm
content: Quote from: SL4P on March 21, 2023, 11:30:27 pmIf you just rotate a colour tube the colours on the screen go crazy, due to its reorientation in the earth's magnetic field. You just need to cycle the power to degauss the mask, and it cleans up. This could be a big issue with things like colour tubes in aircraft, or entertainment systems in buses and trains. I think they had some kind of regularly firing degauss in those.

author: james_s
author_rank: Super Contributor
timestamp: March 22, 2023, 06:08:47 pm
content: Quote from: coppice on March 22, 2023, 02:48:37 pmColor tubes in aircraft were mostly various single gun designs as far as I know, there was the Penetron and another one the name escapes me that used index lines of UV phosphor. I don't think the TVs used in land vehicles typically had anything special, we had a portable color CRT TV that we took on our boat when I was a kid and it was just a standard TV. I don't think TV tubes were as sensitive as high resolution computer monitors, those usually had a degauss button.

author: dmills
author_rank: Super Contributor
timestamp: March 22, 2023, 06:14:20 pm
content: It was certainly an issue for grade 1 picture monitors, had some wind up in NZ and had to fly a guy out to redo the convergence.Mind you, grade 1 monitors were INSANE technology at the time, real cost no object stuff.The effect was not huge, and degauss obviously dealt with the shadow mask magnetisation, but broadcast engineers are picky bastards.

author: tooki
author_rank: Super Contributor
timestamp: March 22, 2023, 07:04:58 pm
content: Quote from: james_s on March 22, 2023, 06:08:47 pmThat’s the beam-index tube, for example the Sony Indextron.

author: coppice
author_rank: Super Contributor
timestamp: March 22, 2023, 07:18:50 pm
content: Quote from: james_s on March 22, 2023, 06:08:47 pmFor aircraft systems that's (at least mostly) the case. For the entertainment systems in passenger aircraft things like Penetrons can't work. They were custom made systems based on conventional picture tubes, and you had to put up with the funky effects as the aircraft navigated.River boats aren't a big problem, except for ferries. The TV is usually only used when a pleasure boat is moored. I remember some really funky pictures on ferries, though. Long distance buses and coaches were also a problem, especially on sections of the journey weaving around towns.

author: DMX
author_rank: Newbie
timestamp: March 22, 2023, 08:37:04 pm
content: No diffrence.

author: james_s
author_rank: Super Contributor
timestamp: March 22, 2023, 08:45:01 pm
content: Quote from: coppice on March 22, 2023, 07:18:50 pmWe used it at anchor too where the boat pivots around with currents and tide. For a while you could buy fancy vans that had a CRT TV built in for the rear seat passengers and I don't think there was anything special about those either. Small tubes with relatively coarse shadow masks are not as sensitive as high resolution or high end broadcast monitor tubes.

author: Bud
author_rank: Super Contributor
timestamp: March 22, 2023, 09:54:49 pm
content: Quote from: SL4P on March 21, 2023, 11:30:27 pmThe degaussing coil would need to be flipped 180 degree

author: vk6zgo
author_rank: Super Contributor
timestamp: March 22, 2023, 11:19:49 pm
content: Quote from: dmills on March 22, 2023, 06:14:20 pmYou got done! ---------At TVW7 we did all such things ourselves.I hated delta tubes, as try as you might, it was almost impossible to get them as good as Trinitrons.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 22, 2023, 11:42:02 pm
content: Quote from: Bud on March 22, 2023, 09:54:49 pmThe magnetic field does that every half cycle.By the bye, it is a "fun thing" when the monitor manufacturer inadvertently fits the degaussing coil thermistor for 120v into the 240v position & vice versa.It degausses Ok for years, then suddenly on "turn on" one day, there is a blinding flash & a smell like fireworks.Thankfully, Sonydidjust transpose them, & there was a perfect 240v one in the other position.A bit of a cleanup of the soot, move the correct one to its proper spot, & "bob's your uncle".

author: james_s
author_rank: Super Contributor
timestamp: March 23, 2023, 01:30:21 am
content: Quote from: vk6zgo on March 22, 2023, 11:19:49 pmTrinitrons were in a league of their own right from the start. I still remember the first time I saw one, the appearance of the tube with its vertically flat face was really striking, and the picture was stunning.I've always kind of wanted a vintage delta gun color TV though, they were largely before my time, everything had inline guns by the 80s, less fussing around but not as interesting.