billabs BL27CBOPU hooking up jamma to vga

tcleary

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have this monitor hooked up to a pc, but I'm trying to hook up jamma to the vga connection. jamma has composite sync, vga has horizontal and vertical, so I twisted the horizontal and vertical together and connected that to the composite on the jamma. everything else should be stright forward, connected the grounds together and RGB to their respective jamma connection. I used a vga breakout cable that was labeled so all the connections should be right. but I get no picture, just a blank screen.

the monitor is getting something though because when nothing is connected it displays "disconnect" but when I turn on the jamma setup i get a blank screen.

at this point I'm assuming it has something to do with the vga input on the monitor not liking composite sync? not sure what else it could be. I know the jamma board is getting power because it has a led.

so the next thing I am going to try is to use the other connector on the monitor, but I don't know what it is. does anyone know where I could get a connector like this and the pins so I could wire it up to jamma? it is a 6 pin connector below the vga, my camera is crappy at taking close up photos.

now that i think about it I think the cable was meant to go the other way, for example vga coming out of the pc into the breakout to the arcade monitor, combining horizontal and vertical into composite.

what I'm doing is the opposite which I guess does not work! so I have to use the other connector I think.

IM000427.JPG
 
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have this monitor hooked up to a pc, but I'm trying to hook up jamma to the vga connection. jamma has composite sync, vga has horizontal and vertical, so I twisted the horizontal and vertical together and connected that to the composite on the jamma. everything else should be stright forward, connected the grounds together and RGB to their respective jamma connection. I used a vga breakout cable that was labeled so all the connections should be right. but I get no picture, just a blank screen.

the monitor is getting something though because when nothing is connected it displays "disconnect" but when I turn on the jamma setup i get a blank screen.

at this point I'm assuming it has something to do with the vga input on the monitor not liking composite sync? not sure what else it could be. I know the jamma board is getting power because it has a led.

so the next thing I am going to try is to use the other connector on the monitor, but I don't know what it is. does anyone know where I could get a connector like this and the pins so I could wire it up to jamma? it is a 6 pin connector below the vga, my camera is crappy at taking close up photos.

now that i think about it I think the cable was meant to go the other way, for example vga coming out of the pc into the breakout to the arcade monitor, combining horizontal and vertical into composite.

what I'm doing is the opposite which I guess does not work! so I have to use the other connector I think.

Your monitor may not be capable of syncing to CGA/EGA.

Nevermind... It would seem that your monitor can scan to the lower frequencies. Your issue is probably how you have the SYNC connected. Try connecting the composite SYNC to the Horizontal sync on your monitor. If that doesnt work try just the vertical sync connection. If those dont work then you probably need to separate the syncs.

Matt
 
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bingo! thanks a lot. I now have a picture. it seems like there is a lack of color though, I tried messing with the monitor brightness and contrast but I can't seem to get it looking as good as it should. maybe I need a video amplifier since it is going through vga? any ideas?
 

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Looks like its missing green maybe - check your connections. Another possibility is that you don't have the colors connected right. Does the board have a test button that can give you a color test pattern to go by?
 
good idea. I'll try wiring up the service and test switches. I know Rastan has a pretty good test menu, I should have thought of that. another thing it might be is the wires on the vga breakout cable I used were really puny, i think a heavier gauge connection might also help, now that I think about it blue might be missing, the main thing that looked odd was the sky in the first level, I bet that's what it is. will check tomorrow. thanks!
 
Does the test mode label the colors though? That will prove that all 3 are connected, but not in the right order. Kinda hard to get it wrong but I've done dumber stuff myself.
 
new problem. when trying to hook up mvs to this monitor I cannot get a picture, something to do with the sync. mvs has composite sync, running that to vga. tried hooking it to the horizontal (which worked for rastan) and all i get is a white flash. tried hooking it to vertical and i get a scrambled picture. tried hooking the composite to both horizontal and vertical and I get nothing. I think I'm out of options and apparently it is impossible to hook up MVS to this monitor which is nonsense. i guess I can try the other connector (6 pin flat) but I'll be hooking up the same connections so I don't think it will matter.
 
anyone have any ideas why a MVS board will not work through this monitor while a jamma board will? they have the same exact video output configuration.

I know the mvs boards I'm trying are good because I was able to get a picture on an electrohome g07. I know the video connections are correct because I was able to get a picture on the billabs with a standard jamma board (rastan)

so something about the combination of this monitor and MVS. I have a hard time believing they are truly incompatible.
 
guess it was not meant to be, i tried hooking up the 6 pin connector and have the same problem, white flash with mvs, that's it. good news is rastan looks a lot better through this connection, so this cabinet will probably become a multijamma/mame only, no MVS.

which means I need a neo geo cabinet, maybe I can find a good deal on a big red
 
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