/vr/ - Retro Games

>>5486641
>>5486726
Also:
For genesis sync, if you choose to use the CSYNC signal directly, you should definitely buffer it somehow. I used an 74LS08, but anything would work. an LM1881 would probably provide a more pedantically 'correct' 1vpp sync pulse, but I can tell you my PVM collection has all worked fine with TTL sync from a 7400 series chip.

If you use composite video for sync like I believe your pic does, your image will shift left and right slightly when the intensity of colors on screen changes. But it will work without any chips.

If you don't buffer the raw csync line, you won't get a picture at all because the csync signal from the genesis is on an open collector output from the genesis VDP. When connected, the load from the TV will temporarily cripple the VDP.

Sync buffer diagram of sorts

>>2827369
I should mention I learned something about genesis sync today. My PVM was getting a black image when I tried to use composite sync on it, because the PVM was drawing too much current on the sync line and causing the RGB encoder chip in the genesis to flip out. I fixed this by adding a 74ls08 chip (any TTL logic or buffer chip should work if you can keep positive logic) between the sync pin of the DIN connector on the back and the input to my PVM. Eventually I just moved this inside my console because I was drilling RCA jacks into it anyway.

Here's an explanation of how I did it in pic related. This was already known on some forums and IRC but I've not seen it very well known. If you've been having trouble with Genesis RGB unless you sync to composite video, here's how you can avoid composite video or sync strippers and use the csync pin on the DIN connector properly.