I have a Yamaha RX-V673 av receiver, a direct tv receiver and a mitsubishi HC3000 projector, connected via HDMI. Everything was working fine until the other day when I began to get sound but no picture. The screen read "no signal." I connected the component video cables from the direct tv receiver to the RX-V673 and from there to the projector. The projector was still set to HDMI. Now I get video and sound? Anybody have an explanation for that one?