var left = new Image();
var right = new Image();
var empty = new Image();
left.src = "images/BG_MenuTunerLeft.jpg";
right.src = "images/BG_MenuTunerRight.jpg";
empty.src = "images/ICON_blank.gif";

function turnOn(id) {
	var theimg = document.getElementById('pos' + id);
	if (id <= 3)
		theimg.src = left.src;
	else
		theimg.src = right.src;
}

function turnOff(id) {
	var theimg = document.getElementById('pos' + id);
	theimg.src = empty.src;
}