I have a magnavox tv single output for antenna, cable box hd, rf connector, and jvc dvd/ recorder. I recently upgraded to hd cable box because old box was dropping channels and pixilated. Now can't access any menus on jvc dr-mvi150b recorder. Worked before changed cable box. Any suggestions on how to hook up system or do I need to change cable box to no hd. Tv is not hd. Please help. THX