07-08-2018, 09:15 PM
I wanted to get an idea about the timebases frequency / linearity and tube condition etc so I've hacked together a VGA to compositeinterface to use withthe modeline utility on my old laptop. The output is fed directley into the grid of the video amplifier - I disconnected the detector diode to gain a little contrast, still not quite enough though.
Something isnt right with the video standard though as its outout has 60Hz frame and 12.14 kHz line frequencies. The frame linearity looks approximateley correct but I cant get the height to fill the screen. The width is too wide and the focus is right at one end of its travell. The width control doesnt seem to do much either. I suspect there isnt enough EHT but I havn't set up to measure it yet and anyway with the line frequency so far off its probably not a good time to test it.
I'll try an older computer to see if I can get a proper 405 line standard output to feed into the set. Apart from the obvious failings its good to something on the screen :-)
Kind regards, David.
Something isnt right with the video standard though as its outout has 60Hz frame and 12.14 kHz line frequencies. The frame linearity looks approximateley correct but I cant get the height to fill the screen. The width is too wide and the focus is right at one end of its travell. The width control doesnt seem to do much either. I suspect there isnt enough EHT but I havn't set up to measure it yet and anyway with the line frequency so far off its probably not a good time to test it.
I'll try an older computer to see if I can get a proper 405 line standard output to feed into the set. Apart from the obvious failings its good to something on the screen :-)
Kind regards, David.
