Picture issue with Naomi, Capcom IO and Sigma Raijin

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OldFoo

Picture issue with Naomi, Capcom IO and Sigma Raijin

Post by OldFoo »

Hi :smt006



This is my setup:

Sega Naomi (Capcom vs SNK cartridge) -> Capcom I/O -> Sigma Raijin (JAMMA control box) -> TV CRT Grundig 14' (an old model)



I have a picture issue that I do not know if it depends on the Naomi, the Sigma Raijin or TV.



Using an European RGB SCART cable from Sigma Raijin RGB output to TV input, picture is displayed but it is not centered at all, it has too much contrast, the edges of writings and characters are blurred or doubled, and mostly the upper part of the image blinks rapidly (flicker... I am not a technician but it seems like a frequency issue?).



Using a SCART RGB 21 (Japanese) cable with an European SCART RGB adapter the result does not change.



Using a composite cable connected from Sigma Raijin S-VHS output to TV, the image is not displayed correctly at all: on a black background I get only some portions of the picture scrolling horizontally.



The dipswitches on Naomi are set as follows:

1 UP

2-3-4 DOWN



Of course the Scart RGB cables work both well on Sigma Raijin with other JAMMA boards.



At the moment I only have a TV for testing, but some time ago I had a different model of TV: I remember that with the Scart RGB cable image was always too bright and with a sort of "line of light" in the middle, while using the composite video it was OK (but not in RGB quality, of course).



Someone could you help me to clarify the situation definitively?

Is my Naomi board damaged? Or TV incompatible?

It is correct to set video to 15Hz with a Capcom IO board?



Thank you very much for your help.
OldFoo

Post by OldFoo »

Yes you can use 15 khz video through capcom I/Os.



First I would check the CSYNC / H/V SYNC switch on the CAPCOM IO. It's next to the 2/4 player switch, near the JAMMA edge. The encoder needs composite sync, however, this switch seems to work backwards and select source sync provided and not output. Since NAOMI uses H/V sync for VGA, When I use my capcom I/O I set it to H/VSYNC, and I get good clean Composite sync output. If I select csync on the IO switch I actually lose V HOLD and the picture rolls.



If the picture is too bright, are there pots on your encoder? Otherwise, try a resistor somewhere from 75 ohm to 220 ohm in series on each of the R G and B wires between the IO and video encoder. When I use NAOMI with a scart type display I use 220 OHM resistors on all 4 JAMMA video lines (R G B and Sync).
OldFoo

Post by OldFoo »

skate323k137 wrote:Yes you can use 15 khz video through capcom I/Os.



First I would check the CSYNC / H/V SYNC switch on the CAPCOM IO. It's next to the 2/4 player switch, near the JAMMA edge. The encoder needs composite sync, however, this switch seems to work backwards and select source sync provided and not output. Since NAOMI uses H/V sync for VGA, When I use my capcom I/O I set it to H/VSYNC, and I get good clean Composite sync output. If I select csync on the IO switch I actually lose V HOLD and the picture rolls.



If the picture is too bright, are there pots on your encoder? Otherwise, try a resistor somewhere from 75 ohm to 220 ohm in series on each of the R G and B wires between the IO and video encoder. When I use NAOMI with a scart type display I use 220 OHM resistors on all 4 JAMMA video lines (R G B and Sync).


Hi and thank you for your answer.



I will check the CSYNC - H/V SYNC switch on the CAPCOM IO.

By the way, I'm not expert so what is this switch about? :smt017



For the picture too bright, this is my supergun:



http://wiki.arcadeotaku.com/w/Sigma_Raijin



...as you can see there is a S-BR pot that is only for brightness on S-Video and Composite, while I'm using RGB via SCART.



Where should I check the resistors?



Thank you



EDIT: Here also it seems that H/V SYNC is the way...



http://www.neo-geo.com/forums/showthrea ... z-question
OldFoo

Post by OldFoo »

If that supergun has its own SCART output you should not need to add resistors yourself. As long as other boards look OK and the NAOMI is not too bright.



As far as sync, most VGA display (31khz) use two wires for sync, one for horizontal and one for vertical sync. Most JAMMA boards (15 khz) and SCART RGB uses only one wire for sync called composite sync. Since the NAOMI supports both 15 and 31khz I think this is why the capcom IO has to be set to accept H/V separate, even though it outputs composite sync.
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