Death of the tube TV

[frenchy]

The Hitachi projection set I have has a super-keeno adjustment grid for the convergence where you can make the convergence perfect from edge to edge... the convergence is controlled by the electronics and not just statically set at the factory. Of course it also has auto convergence along with this and I assume it accomplishes this with sensors inside the screen, which a crt cannot accomodate. But I could see where this type of technology could be applied to a crt set to with the convergence being electronically 'dialed in' at the factory with a grid like this and not just adjustment rings on the tube itself. Or do they do that already, I don't know.

[Chad Hauris]

The delta gun crt's and older GE inlines did have electronically controlled convergence (convergence coils)...this is why it is called dynamic convergence as it uses a changing electronic signal. I wonder why modern inline tubes did not use a convergence coil setup which could be controlled by more sophisticated electronics than the old convergence control boards?

[Geoff Bourquin]

I've recently seen some Philips CRTs with no magnets on the neck, only a coil connected to a small board with some surface mount ICs and a power IC on a heatsink. I've seen these CRTs in Toshiba TVs. I haven't researched how the alignment is done, but I suppose there is a memory somewhere storing data that decides what goes to the coil. This could allow alignment to be precise across the entire screen just like the digital convergence on projection TVs.


Anyone else remember the super-flat inline CRTs RCA used in the late 70s or early 80s? They had a CTC-eighty-something chassis I think. I remember the edge and corner focus being pretty bad.

It's sad to see the CRT fading away, especially when you consider how good it looks.
It's also sad to see the CRT fading away, when you're a guy who has spent the last 25 years keeping them running.

[andy]

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[andy]

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[Geoff Bourquin]

Andy said:

I think those Philips CRTs actually have the convergence magnets INSIDE the electron gun. They are adjusted by magnetizing them precisely when the CRT is manufactured. How many wires go to the coil on the neck? If it's only 2, it's for scan velocity modulation (edge enhancement).

It does have only 2 wires, but I don't think this is SVM; if you disconnect this coil, purity and convergence goes way off. The drive for it comes from the small circuit board mounted on the yoke. I don't see any connection to video for SVM.

Now I've got to go find out exactly how does it works.