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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 28th Dec 2019, 12:06 pm   #21
Welsh Anorak
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Default Re: Which TV for RGB scart?

Your problem could be the CRT, of course. but there might be a problem in the coupling, possibly a capacitor in the cathode drive. As you have three channels, some swapping of components might be in order. Changing the red and blue cathodes might reveal something, but often confuses the auto grey-scale so you're not much better off. However a mono test pattern and a 'scope might be the quickest option.
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Old 31st Dec 2019, 8:47 pm   #22
3CX15000A7
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Default Re: Which TV for RGB scart?

Quote:
Originally Posted by ben View Post
Quote:
Originally Posted by 3CX15000A7 View Post

Is there something I can look for on the RGB amplifier panel/Small signal board? Capacitors? Some fault in the cut-off feedback? I have to dig in the schematics.
Change the cap in the supply to the RGB stage. Typically a low value (22uf or less) rated 160v or more. That may reduce or remove the smearing and improve the consistency of the black level across the width of the screen.
I replaced cap 2442 on the main board from the +200V supply and cap 2360 on the RGB pcb. I used the same value (only a higher voltage for 2360).

It did not had any effect on the picture quality. There's no improvement, but it isn't worse either.

Or should I use special low ESR types?

@Welsh Anorak
I have a scope and a Grundig VG1000 pattern generator. Later on this week I will look if those machines are still functioning and maybe we can do some measurements!

@NTSCuser
I think the 16:9 switch became standard around the mid 90s. My Anubis B set from 1993 doesn't have one either. You can adjust the vertical amplitude (this is what a 16:9 switch does automatically, nothing more) if you want to get the extra resolution, but it's fixed 16:9 then. .
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Old 2nd Jan 2020, 11:06 am   #23
Welsh Anorak
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Default Re: Which TV for RGB scart?

I doubt a low-ESR type would make any difference as long as the one you've used is a good make. Hopefully your 'scope will show us where things are going wrong.
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