Graphical problem with choplifter

kruuth

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I'm using a Choplifter with a System 8 to Jamma. It's not working correctly. There are problems with the graphics. Can someone tell me how to repair this?



It's done this on several monitors.
 
You are missing the video sync signal, check that the harness is correctly wired up for this pin, if it is correctly wired up then you have a PCB fault.
 
Since it's happening on multiple boards I'm going to say I'm missing the sync. What Sync does it use?
 
Your monitor wiring has 5 wires going to it from the game pcb - red, green, blue, ground, and composite sync. Depending on which monitor chassis you connect it to will depend on how you connect it.

That being said, I have two working Choplifter boards. One will sync perfectly with the sync connected to the negative sync pins. The other will sync perfectly with the sync connected to the positive sync pins. Both boards look exactly the same as far as I can tell, so I'm not sure what the difference is.

I also used an adaptor. If it was home-built, you should also check to make sure the sync is jumpered properly...
 
Video ground looks ok, if you are missing that the picture looks very "oily", thats the best way I can describe it, distorted in ripples with all the colours running into each other. The above image looks a bit clean for that, tho anythings possible. Its either sync or ground thats missing, or both.
 
Can you elaborate more? I've hooked it into another monitor and I'm getting roughly the same effect. Would a video help?
 
On another note, system 8 boards didn't have a video ground....
 
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