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Re: S-Video conversion possible as plug-and-play solution?

Posted: Mon Jun 13, 2016 4:49 pm
by Oge_user
You could try amplifying the Chroma and then 0,1uF/1uF bipolar capacitor plus 470/1000 Ohm resistor between VIC and TV in order to protect the VIC itself. And a 75 Ohm (Chroma to GND) resistor as a final touch.

Connecting chroma straight on TV was discouraged several times while testing with the C64 S-Video modifications for the purpose of protecting the VIC-II.

In case of straight connections of Chroma to TV the quality will strongly vary depending solely (IMO) on the quality of the inner circuits of the TV. On CRTs you can still get a good result with VIC>TV direct connection.


Cheers,
Oge

Re: S-Video conversion possible as plug-and-play solution?

Posted: Mon Jul 18, 2016 11:33 am
by RobertBe
I wrote:Using Eslapion's above solution as a starting point, Ray Carlsen just modded my main NTSC VIC-20 for s-video!
I was so pleased with the VIC-20CR that Ray modded for s-video that I'm having him mod my early (PET-key-style) NTSC VIC-20 for s-video.

Writing from Victoria, B.C,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm
July 30-31 Commodore Vegas Expo v12 -
http://www.portcommodore.com/commvex

Re: S-Video conversion possible as plug-and-play solution?

Posted: Mon Jul 18, 2016 12:48 pm
by eslapion
RobertBe wrote:I was so pleased with the VIC-20CR that Ray modded for s-video that I'm having him mod my early (PET-key-style) NTSC VIC-20 for s-video.
IMHO, the S-Video mod on older VICs brings the best results. Early VICs have better quality video amplifiers which produce less video noise.
Writing from Victoria, B.C.
Have a nice trip in Canada!

Re: S-Video conversion possible as plug-and-play solution?

Posted: Mon Jul 18, 2016 1:19 pm
by RobertBe
eslapion wrote:IMHO, the S-Video mod on older VICs brings the best results
Heh, I probably won't be able to tell the difference in quality from a s-video modded older VIC and a s-video modded VIC CR.
Have a nice trip in Canada!
Thanks! This is my fourth time to Victoria. Now it's time to get out of the hotel room and explore the shops, restaurants, and Chinatown. (Not necessarily in that order...) :)

Writing from Victoria, B.C.,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm
July 30-31 Commodore Vegas Expo v12 -
http://www.portcommodore.com/commvex

Re: S-Video conversion possible as plug-and-play solution?

Posted: Tue Jul 19, 2016 6:02 am
by Boray
eslapion wrote: IMHO, the S-Video mod on older VICs brings the best results.
I guess you ment later vics? Or do you mean an early model modded will bring the very best?

Re: S-Video conversion possible as plug-and-play solution?

Posted: Tue Jul 19, 2016 6:23 am
by eslapion
Boray wrote:I guess you ment later vics? Or do you mean an early model modded will bring the very best?
I mean...
Early VICs have better quality video amplifiers which produce less video noise.
Which means the s-video mod will make biggest impact on late models. Biggest impact = best result.

Re: S-Video conversion possible as plug-and-play solution?

Posted: Tue Jul 19, 2016 11:14 am
by RobertBe
eslapion wrote:
RobertBe wrote:Early VICs have better quality video amplifiers which produce less video noise.
Ray wrote to me last night that the VIC I turned in for repairs has a board he's never seen before - one where the major chips are fully socketed. Since that is the case, it will be easy to add JiffyDOS and a R65C02 to it.

Going to the ViC 64 club of Victoria tonight,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm
July 30-31 Commodore Vegas Expo v12 -
http://www.portcommodore.com/commvex

Re: S-Video conversion possible as plug-and-play solution?

Posted: Tue Jul 19, 2016 12:05 pm
by mrr19121970
What board & REV number is it?

Re: S-Video conversion possible as plug-and-play solution?

Posted: Tue Jul 19, 2016 12:17 pm
by RobertBe
Ray says it's a "very early E version."

Going to the ViC 64 club of Victoria tonight,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm
July 30-31 Commodore Vegas Expo v12 -
http://www.portcommodore.com/commvex

Re: S-Video conversion possible as plug-and-play solution?

Posted: Wed Jul 20, 2016 4:02 am
by Boray
eslapion wrote: I mean...
Early VICs have better quality video amplifiers which produce less video noise.
Which means the s-video mod will make biggest impact on late models. Biggest impact = best result.

Re: S-Video conversion possible as plug-and-play solution?

Posted: Wed Jul 20, 2016 8:14 am
by mrr19121970
I second this.

Re: S-Video conversion possible as plug-and-play solution?

Posted: Wed Jul 20, 2016 11:03 am
by eslapion
@mrr19121970 & Boray

Unfortunately that's not what I saw.

The S-Video mod improves the image resolution significantly but the VIC-20cr has a lot of unfiltered noise in its video signal mostly caused by the video amplifier's poor choice of components.

Since the S-Video mod still uses the onboard video amplifier for the luma+sync signal, the noise stays there. In the end, the older VIC-20s provide a better image quality without or without the S-Video mod. This mod providing an equivalent improvement on both machines, the 2-Prong PSU VIC-20s with S-Video mod are the ones giving the best image quality overall.

Re: S-Video conversion possible as plug-and-play solution?

Posted: Wed Jul 20, 2016 12:18 pm
by Boray
eslapion wrote:This mod providing an equivalent improvement on both machines,
Well, most CR machines suffer from severe graphics graininess which this mod cures.

Re: S-Video conversion possible as plug-and-play solution?

Posted: Wed Jul 20, 2016 2:22 pm
by Boray
Boray wrote:
eslapion wrote:This mod providing an equivalent improvement on both machines,
Well, most CR machines suffer from severe graphics graininess which this mod cures.
Is this only a PAL land problem???

Re: S-Video conversion possible as plug-and-play solution?

Posted: Thu Jul 21, 2016 12:44 am
by eslapion
Boray wrote:Is this only a PAL land problem???
It's possible. I have a PAL VIC-20cr which doesn't have the S-Video mod and I noticed the color encoding does cause a serious polka dot pattern.

It seems the color encoding on PAL VICs is not phase alternating from one video jiffy to the next as it is on NTSC VICs.

However, this effect is caused by the way the video chip works, not by the video amplifier, so it should be the same on all PAL VIC-20s.