The Intec Gamecube screen requires both a 12 volt DC input and the AV input. The larger connection is the AV cable which plugs into the back of the Gamecube console. The smaller round cable is the 12 volt DC input cable that goes to the power source for your screen. The solution is to either get the original splitter cable that splits the DC power to the screen and the Gamecube, or use separate 12 v DC inputs for each device. These original Intec splitter cables are rare and are not cheap, and the only place I have found them for sale is at the NES Repair Shop:

http://nesrepairshop.com/online_shopping/index.php?productID=645



The only other solution is having separate 12 v input cables for the screen and the Gamecube. And finding the right size (very small) is also a task.

If you don't have the money for the splitter $50+ and want to try using two separate power sources a wd external hard drive power cord will work. I had model number ksas0241200150hu work. Sells on Amazon for $7

Here i hopes this helps

There should be more connection slots in the bottom.