JAMMA board scrambled my Stargate monitor

keithlee

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Newb here. I am converting my Stargate to a multi-williams using a programmable PCB. I bought a plug-and-play JAMMA harness from arcadeshop. There was one 6-pin molex connector that I plugged into the monitor. When I powered on the game, the screen was scrambled(like a H or V-hold issue). I tried to adjust the monitor to no avail, but don't really know what I'm doing. I hear sounds from the speaker so I think the board is working. The monitor worked fine before I hooked up the JAMMA board.

Any help is appreciated.
Shawn
 
Well, depending on what monitor you have, you probably need to move the sync wiring from the 6-pin molex to a 3-pin molex and connect it to the other three pins there by the 6 pins...
 
Bless you for responding! The sync wire is jumpered to pins 1 and 2(left to right). There is an empty 3-pin connector above the 6 pin. How do I connect the sync wire to this 3-pin connector?

thanks again,
Shawn(clueless newb)
 
Well, you'll need another 3-pin molex housing and then move the pins over there to the last two pins (in the same order). I assume that since the MW is JAMMA it is also negative sync, unlike the SG you had before..
 
To clarify: I should move the jumpered sync wire from pins 1 and 2 on the 6-pin connector to pins 1 and 2 on the 3-pin connector? Do I leave the 3rd pin empty, as well as the vacated pins 1 and 2 on the 6-pin connector?

thanks for your patience.
Shawn
 
Stargate uses positve sync, Jamma games use negative sync. The negative sync input is that three pin molex connector, while the positive sync wires are part of the main video input connector (six pin molex). So, for Jamma use, you'll need to move the sync wires from the six pin connector to their appropriate pins on the three pin connector.

-Ian
 
I moved the jumpered sync wires to pins 1 and 2(left to right) with no improvement. tried connecting them to pins 2 and 3 but still no better. Can someone explain exactly how I am supposed to connect these wires?

thanks,
Shawn
 
You need to get the schematic for that monitor and the board/harness. Make sure the -H and -V on the game are delivered to the -H and -V pins on the monitor.
 
I think I have a Electrohome g07. I have been numbering the pins backwards. Vertical sync is pin 5 and horizontal sync is pin 6 on J201. So, how do I connect the sync wire from my Jamma harness to J202 (pin 2 vertical, pin 3 horizontal, pin 1 ?).

thanks again and forgive my ignorance.
Shawn
 
you need to remove the sync wires from the 6 pin connector and get a 3 pin connector and install them in that...you need 2 seperate connectors
 
Wow! This has been very instructive. So, if I understand correctly, I just need to move the composite sync wires to pins 2 and 3 on J202. Do I then just need to re-adjust v-hold and horiz freq to unscramble the picture or do I need to fiddle with something else?
Shawn
 
Since you have tweaked then trying to resolve the sync issue, they will likely need some adjustment. The other adjustments are for color, brightness, contract, etc. They may need tweaking, but not to obtain a stable image.

If you have messed with screen position/size, they may affect stability at their extremes. That's unlikely and could be eliminated by setting median values and adjusting once you have a stable picture.
 
If you had separate sync before, you should know that you'll need to connect the composite sync to both the -H and -V pin - assuming you have a G07. Check and make sure, because if you have a certain type of Well-Gardner instead (like a 4900) , then you only connect the -H...
 
Success!!!

Moving the sync wires solved the problem. I am immeasurably grateful to the generous souls who helped me! Since I have no technical ability to give back to the group, perhaps some monetary donation to a KLOV-related benefactor would be useful. I will probably donate to the International Arcade Museum Library unless I receive a different recommendation.

sincere thanks to all,
Shawn
 
your offer of generosity is very kind...we're just a bunch of guys (and a few girls) that love collecting and helping each other out
 
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