Philips Videopac + G7400

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I am very happy owner of two G7400s with working power buttons 

[kcmunchkin83]

I didn't realize they were so common and not that expensive. Thank you for letting me know and for the appropriate eBay links where I can look for one. Who knows maybe I'll add one to my collection one day.  Any ideas how to make it work in the US?

[VideopacBelgium]

I'm working to build a JOPAC with SGVA output. Maybe you'll be interested.

[Rene_G7400]

Any ideas how to make it work in the US?

Here's some info that might be useful:
http://www.the-nextlevel.com/odyssey2/articles/g7400guide/index.php

[gertk]

I'm working to build a JOPAC with SGVA output. Maybe you'll be interested.

What kind of electronics are you using for this, I assume you are making a scanline doubler ?

From my VGA LCD screen project the biggest problem was creating a new Hsync signal at double the frequency of the normal Hsync.
I used a GAL chip to create a 113 (114) counter but found out later that the VDC is not completely in sync: Quote from kevtris "There's 227.5 cycles per scanline" which explains the random jitter effects on the VDC output (hardly noticable)
The plus graphics part runs cycle perfect. For buffering a complete line I used a TMS4C1050 VRAM chip, it is a 4 bit chip, perfect for the Videopac RGBI system.

[Rene_G7400]

"There's 227.5 cycles per scanline"

This is only true for NTSC consoles (VDC 8244), for PAL consoles (VDC 8245) there are 228 VDC cycles (pixels) per scanline.

[gertk]

This is only true for NTSC consoles (VDC 8244), for PAL consoles (VDC 8245) there are 228 VDC cycles (pixels) per scanline.

Then it should be possible to sample the VDC output 'spot on', just need to know on what clock edge the video data from the VDC is stable. I will have to fire up the oscilloscope to check. Maybe I need a latch instead of a buffer in front of the inputs of the VRAM chip. As i said the output of the plus part is captured perfectly, just the VDC output drifts a bit.