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Vic 20 composite video dodginess

Josh Litherland
 

Hello AHCS!  I only recently became aware of this group, and I'm looking forward to attending my first meeting next Saturday.

When I do, I'll probably be bringing along my ailing Vic 20.  It's an old two-prong model, assy. 324003, and the video output on it is very weak, producing a dark picture.  The RF modulator signal is a bit stronger than the composite, but neither are good.  I've tried swapping my cable from pin 4 to 5, and while both work, neither is particularly brighter than the other.  On modern displays (and my RetroTink line doubler) the composite display isn't strong enough to keep the picture synced and it just drops out to black.

The board appears to have it's original electrolytic capacitors.  Is that where I should be looking?  Any other recommendations on what to try?

Here are some photos of, from left to right, the RF output, composite, and the composite pushed through the component luminance input of the RetroTink, producing the very dark monochrome picture.

https://photos.app.goo.gl/CkXQGmtaUohQVBZcA

Thanks, and I look forward to meeting some of you next weekend!

Pete Rittwage
 

No, it's an easy tweak of a potentiometer on the motherboard. They are tuned for the RF modulator, so any other display is way too dim. 

-Pete




On Fri, Mar 6, 2020 at 01:54 PM, josh@... wrote:
Hello AHCS!  I only recently became aware of this group, and I'm looking forward to attending my first meeting next Saturday.
When I do, I'll probably be bringing along my ailing Vic 20.  It's an old two-prong model, assy. 324003, and the video output on it is very weak, producing a dark picture.  The RF modulator signal is a bit stronger than the composite, but neither are good.  I've tried swapping my cable from pin 4 to 5, and while both work, neither is particularly brighter than the other.  On modern displays (and my RetroTink line doubler) the composite display isn't strong enough to keep the picture synced and it just drops out to black.

The board appears to have it's original electrolytic capacitors.  Is that where I should be looking?  Any other recommendations on what to try?

Here are some photos of, from left to right, the RF output, composite, and the composite pushed through the component luminance input of the RetroTink, producing the very dark monochrome picture.

https://photos.app.goo.gl/CkXQGmtaUohQVBZcA

Thanks, and I look forward to meeting some of you next weekend!

Josh Litherland
 

That made a _huge_ difference, thank you!  On a true composite input, the Vic looks great now.  The line doubler still doesn't like it, either not syncing up or displaying a wobbly signal with red ghost images , but I can carry on researching on that front.

Thanks!


On Fri, Mar 6, 2020 at 5:20 PM Pete Rittwage <peter@...> wrote:
No, it's an easy tweak of a potentiometer on the motherboard. They are tuned for the RF modulator, so any other display is way too dim. 

-Pete




On Fri, Mar 6, 2020 at 01:54 PM, josh@... wrote:
Hello AHCS!  I only recently became aware of this group, and I'm looking forward to attending my first meeting next Saturday.
When I do, I'll probably be bringing along my ailing Vic 20.  It's an old two-prong model, assy. 324003, and the video output on it is very weak, producing a dark picture.  The RF modulator signal is a bit stronger than the composite, but neither are good.  I've tried swapping my cable from pin 4 to 5, and while both work, neither is particularly brighter than the other.  On modern displays (and my RetroTink line doubler) the composite display isn't strong enough to keep the picture synced and it just drops out to black.

The board appears to have it's original electrolytic capacitors.  Is that where I should be looking?  Any other recommendations on what to try?

Here are some photos of, from left to right, the RF output, composite, and the composite pushed through the component luminance input of the RetroTink, producing the very dark monochrome picture.

https://photos.app.goo.gl/CkXQGmtaUohQVBZcA

Thanks, and I look forward to meeting some of you next weekend!



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Josh Litherland (josh@...)