sudomod

First: New to the forums, thank you to all of you guys that have put in work to allow a complete newbie learn tons about making stuff. I'd never even soldered before, and now I feel like an old pro. Thanks so much!

So to business I still haven't received all my parts yet, but I'm mostly there. I got this (http://sudomod.com/wiki/index.php?title ... te_Display) screen in the mail today, and after modifying it to work with 5V it worked great with the composite output from an Xbox. But after I hacked off the RCA connectors and wired it up to the Pi I was getting zilch. I checked all the wiring with a multimeter and it was solid. After some trial and error and even resoldering wires to the RCA connector, it seems that I need a ground for my video wire. When retesting with the Xbox output, without the ground wire hooked up to the RCA connector the screen displays nothing, but with it, it works like a champ.

Is there something obvious I'm missing here? Do I need to give the yellow wire a ground to the Pi?

Okay, I think I realize my mistake. I didn't realize that the circular pad beside the TV out pad IS the tv ground pad. From what I had seen other people doing it looked like they were wiring the white audio cable to that pad, so that's what I did even though I realized that didn't really make much sense because there is no way to get audio from that. I'm going to rewire that and then it should work.

But now I don't know what to do with the white audio wire. Do I just leave it hanging? Could I actually leave it connected to the pi and bridge the pins between audio and ground at the connector on the display board with a jumper cable to use it as a ground?

Think this guide should help (thanks @Fleder!)

http://sudomod.com/forum/viewtopic.php?f=22&t=958

Tierod wrote:But now I don't know what to do with the white audio wire. Do I just leave it hanging? Could I actually leave it connected to the pi and bridge the pins between audio and ground at the connector on the display board with a jumper cable to use it as a ground?

The white wire is not for audio, it is your second video input cable.
You could attach 2 Video sources to this display and switch between them via the button board that usually comes with those displays.

You can just ignore it and make sure it does not come in contact with other components.
Use some kind of tape and you should be fine. You can even desolder it, if you want.
But first make sure it works with the choosen one, before you remove it.

SOLVED! After all but giving up, I tried to edit my config.txt again after having no success the first time. I forced composite by turning off HDMI hotplugging. I don't know if this is what I was supposed to do from the beginning or wether it was a wierd bug. Did all of you have to do this? I jumped for joy when I saw that rainbow splash screen. Now, that that's solved it's back to work!

PS: For anyone else with this problem, to force Composite put your SD card with retropie installed and open it up. Your computer should read that card's name is "boot". In there is the config.txt.
Go to the line that says
#sdtv_mode=2
and delete the # symbol (to uncomment it)
Then go to the end of the file and type
hdmi_ignore_hotplug=1

This should force Composite.