Genesis model 1 too dark with RGB cable

Started by grips03, March 01, 2009, 06:56:57 AM

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grips03


viletim

grips03,

Both Master System and Mega Drive have a non-standard sync pulse, it's slightly too wide. They also bring an unbuffered sync pulse to the video output connector. For this reason you shouldn't use the composite sync directly (as you've noticed, you'll loose the video signal completely). Instead use a logic gate to buffer it or derive it from the video signal with an LM1881.

grips03

#42
Just ordered the parts from Newark. The plan is feed composite video (not sync) from Genesis Gen1 to the LM1881. Then take this cleaned up signal and feed the XRGB2.

grips03

#43
Got parts from Newark today and built LM1881 circuit per http://gamesx.com/wiki/doku.php?id=av:lm1881

1) Used composite video to feed pin 2, looked same as without LM1881, same issue old issue.

2) Used sync to feed pin 2 and it was a bit darker, worse.

pin 3,5,7 = no connection
pin 1 = output to XRGB2
pin 2 = input from Genesis Gen 1 with .u1f cap inline before pin 2
pin 4 = Ground from Genesis
pin 6 = .u1f and 680K ohm in parallel, then to Ground
pin 8 = +5 from Genesis

Any ideas?

albino_vulpix

Could the LM1881 be faulty? Try using a different console that outputs composite video and RGB through it.