Please Send Help...

[Atari6600]

Ok, so I've finally started nightly livestreaming for the YouTube channel I work for.  Well, the decided upon game for tonight is Mario Party 6....problem is my "boss" wants me to bring my WAVLink mini av to HDMI converter.  And when I hook the converter up to my TV (I just found out its resolution is 720p) that there is NO SOUND whatsoever when the game system is turned on...

Now for the Genesis issue I had...well the streaming helped me discover it's just a crappy TV.  My girlfriend will be providing a TV that isn't glitchy when she moves in with me this weekend.  However, I don't know if the issue is with the TV...or with the converter.

The sound issue has happened with my Gamecube, Genesis AND Super Nintendo when any of them are hooked up to the converter.  I tried looking online but no avail.  Can anyone help me troubleshoot and figure out what's causing the sound not to work (when I hook the aforementioned systems directly into the AV slots on the TV the sound comes out just fine)?  I get picked up to set up at 9 pm EST, and I'd really appreciate any advice or assistance to make sure it goes smoothly tonight.

Thanks in advance.