Apple II+ Video Out - vertical lines when using low and high res color

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Joined: Apr 18 2009 - 13:30
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Apple II+ Video Out - vertical lines when using low and high res color
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Image icon bwtext.jpg888.44 KB
Image icon dinoscreenshot1.jpg758.5 KB

Hi!

I have an Apple II+ connected to an original Apple Color Monitor (partno: 825 1207 A). The monitor works perfectly, when I connect my camcorder via the composite video input (the only input on this monitor), the image is very nice.

Then when I connect my Apple II+ to the monitor via the on-board video out I get great B & W results (see bwtext.jpg - attached) but then when I switch to low or high res video (color) I get these vertical lines on the screen (see dinoscreenshot.jpg - attached).

any ideas??

Thanks!

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Last seen: 1 month 3 days ago
Joined: Jun 5 2008 - 07:26
Posts: 475
I don't know the particular p

I don't know the particular problem, but schematics reveal that this problem should has to be isolated to one of five chips or the interconnects between them.

I would suspect one of the 74LS194s at B4 and B9 or the 74LS151 at A9. Try swapping the 74LS194s and see if the display changes. There is another 74LS194 at A10 that could also be used to swap (it is also involved in video circuit, so could also be at fault). The 74LS257 at A8 is also involved in color graphics. Try swapping it with another one at different location on the mother board.

If swapping these chips doesn't affect behavior, it's possibly a bad socket or solder joint.

Hope this helps.

Regards,
Mike Willegal

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Last seen: 13 years 11 months ago
Joined: Apr 18 2009 - 13:30
Posts: 3
following up on this

thanks for your help with this...been a long time since you emailed me about this issue. I tried swapping chips to no avail. Do you know of an Apple II+ video card I could pop into one of the slots that would then give me another, re-routed composite video output?

Thanks again

John

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