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 Post subject: Re: CRTC chip
PostPosted: Wed Aug 08, 2012 1:26 am 
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Joined: Mon Aug 08, 2011 2:48 pm
Posts: 808
Location: Croatia
After debating on a Serbian forum(http://www.elitesecurity.org/) a while ago my color issues, they recommended to use some fancy opamp, which i couldn't find in my local shop, so they remembered that they use to have the tl081 in video amps, so i bought it, and i lost it :mrgreen: , but i found a similar opamp at home that has 3MHz bandwidth, so i decided to use it. After some soldering and debugging, i got the colors finally!
But now i am having synchronization issues. In text mode the picture is ok, but i can see diagonal color strikes jumping on the screen, but when i switch to full graphic mode horizontal sync goes crazy, and the picture starts scrolling, and its folded at the top and bottom.
Any tricks to fine tune the picture?

Edit: The opamp acts as a voltage follower, so it prevents the low impedance video amp to kill the signal. The issue is that the output voltage has a 3V offset, so i used a cap to get ac values, but when i use the cap, the signal gets lazy(slew rate starts killing it)and wavy(that is at least what i see on the scope).


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