Author Topic: 21" tube to a 28" TV chassis? (Read 2644 times)

Paradise · « **on:** February 08, 2019, 05:47:06 am »

Is it possible to connect a 21" tube to a chassis that had a 28" tube if the neck board has the same pins?

Last month i bought a CRT Regenerator/Analyzer for $45:

In the adapter list i see that the 21", 25" and 28" tubes i have need the same adapter.

princess prin prin · « **Reply #1 on:** February 08, 2019, 08:24:26 am »

The CRT base type means nothing. You can have the same base on tubes starting from 14" through to 29" and bigger but that doesn't mean that a chassis made for a 14" CRT will work fine on a 28" CRT just because the neckboard fits both.

As a general rule you can divide CRTs in two basic groups depending on the deflection angle. 90° CRTs are 14" through to 21" (there are some 21" tubes that are 110° but they're an exception) and 110° CRTs are 25" and 28" (22" became obsolete in the 80s). 29" are 110° or some other angle close to that (e.g. 114°). 100° were also made but long ago and mostly in the US, not in Europe. A chassis made for 90° tubes will not work with a 110° tube (EHT requirements are different, line output circuit is different, scan coils aka yokes are different, etc.) and vice versa. And even within the same group you'll often find that the same chassis may have slight differences if made for a 14" from one made for a 21" or for a CRT made by one manufacturer and another CRT of the same size made by another manufacturer. Without detailed information on chassis circuit variants try at least not to mix 90° with 110° CRTS/chassis.

Paradise · « **Reply #2 on:** February 08, 2019, 08:34:56 am »

To bad because all the 21" TVs i collected now that have the right chassis for MAME have Toshiba tubes with bad convergence.

And i just realized that the 25" and 28" tubes i have don't have convergence rings???
Looked at just one 25" (A59EAK071X01) TV yet and also bad convergence.

princess prin prin · « **Reply #3 on:** February 08, 2019, 09:07:59 am »

All your tubes have bad convergence? Aren't you a bit too demanding?

Philips tubes are unique in that they have a single internal ring that is located at the end of the electron gun assembly and is magnetized at factory with an external apparatus with all the necessary purity and static convergence corrections. Static convergence is the convergence in the central area of the screen. If there are any dynamic convergence issues (miscongvergence in corners/peripheral areas) these are not adjusted by rings but with yoke tilting and spoilers (aka convergence strips) although it should be noted that Philips NEVER used those strips but you can try them.

Paradise · « **Reply #4 on:** February 08, 2019, 10:02:28 am »

Maybe i'm to demanding. I don't know what is good, acceptable or bad.

21" Toshiba:

Paradroid · « **Reply #5 on:** February 08, 2019, 01:44:03 pm »

Quote from: Paradise on February 08, 2019, 10:02:28 am

Maybe i'm to demanding.

Definitely too demanding.

Sent from my SM-G955F using Tapatalk

Paradise · « **Reply #6 on:** February 09, 2019, 04:47:52 am »

buttersoft · « **Reply #7 on:** February 11, 2019, 08:34:23 pm »

Someone else's CRT always looks better than your own

Paradise · « **Reply #8 on:** February 13, 2019, 07:03:37 am »

That means i have to bring my secret weapon to the fight - the Sony GDM-FW900


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Author Topic: 21" tube to a 28" TV chassis? (Read 2644 times)

Paradise

21" tube to a 28" TV chassis?

princess prin prin

Re: 21" tube to a 28" TV chassis?

Paradise

Re: 21" tube to a 28" TV chassis?

princess prin prin

Re: 21" tube to a 28" TV chassis?

Paradise

Re: 21" tube to a 28" TV chassis?

Paradroid

Re: 21" tube to a 28" TV chassis?

Paradise

Re: 21" tube to a 28" TV chassis?

buttersoft

Re: 21" tube to a 28" TV chassis?

Paradise

Re: 21" tube to a 28" TV chassis?