My Sony STR DH-800 receiver has been working fine till this morning when I turned it on. Audio is coming through the speakers fine but no video signal is being outputted to the projector. I have tried multiple cables and sources. I have tested the projector and it is working fine. I have tested the sources and cables and they are fine. My amp only has one HDMI video out. Any suggestions as to what could be the problem and if I can fix it myself? No settings have been changed since it was working fine last night. Thanks.