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Author Topic: Dreamcast VGA box to JAMMA hack = dull image + other questions (n00b alert)  (Read 3009 times)

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hanspecans

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    • arsty farsty
Hi everyone this forum has been extremely helpful in trying to hook up my dreamcast to my JAMMA cabinet.
i have the orange cased dreamcast vga box. i cut the wire to pin 6 and the other instructions on this and other sites and viola. now i have a steady synced image. however the image is very very dull. i ASSume this has something to do with the vga box not amplifying the signal? i assume this because when i cut the 5v from the DC pinout it doesn't change anything. I also tried using the 5v from the JAMMA biscuit to the 5v DC connector and that didn't change anything either. my monitor looks great with my actual Jamma PCBs. so can you please help me?!

i did try to identify my monitor as the rules stated but i can only find info for the tube. i see no identifying marks on the chassis.

here are some pics.

bonus round. where the hell is the ground for the pushbuttons on this DC madcatz controller. (sorry i swear to god i searched all night and this morning)

hanspecans

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    • arsty farsty
yes i know i can buy a video amp from ultimarc but i'm trying to save some $$$ here. plus i've read so many people doing this hack with no problems. on top of that the chips for the amp seem to be in the VGA box anyway. so i'm hoping maybe someone can guide me to some added hack to get this up and running.
i would've built the chip involving the LM1881N etc but alas radioshack of course doesn't have them and i've have to special order them. in which case i'd just forget it and order the ultimarc dreamcast av to jamma converter. but that's no fun.

Kevin Mullins

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Just curious.... but have you tried bumping the brightness, contrast or screen voltage up on the monitor itself ?
Each individual color can be adjusted as well.

Since you seem to have a nice clean and stable image, I bet you could adjust it out some.
Not a technician . . . . just a DIY'er.

hanspecans

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    • arsty farsty
i haven't tried it because then my other games would suddenly be way too bright. as i said in the OP my other jamma boards look great when i put them on .  plus i think it would just make everything even brighter. maybe i'll try it anyway though.


but as you can see it seems to be a weak signal going in. so i'm hoping there's some simple fix. although i have a feeling i'm going to end up buying some kind of ultimarc adapter.

hanspecans

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ok i did try that suggestion of turning the brightness up on the monitor and all it does, as predicted is make a grayer or whiter color. not a more vibrant strong color. everything stays dull.