83 chexx no sound

[Jeff 83]

Hi ,
Just picked up a 83 chexx with the blue base. Everything seems to work ok but there is no sound at all. Guy I bought it from said it never had sound when he owned it either. He checked the speakers and said they were good. I also did check the volume knob! There is a plug that is not plugged in but I don't see a place for it on the board to plug in. Any help would be greatly appreciated!!
Thanks
Jeff

[peter2626]

check the board.  It may be a sound chip..Look for the schematics on where it is located