You might try removing the HDMI board and cleaning the contacts with contact cleaning solution. The HDMI board can be removed by removing two screws on back. The top cover has to removed so that you can carefully push the circuit board out. Give this a try before send the unit in for repair.
KRELL 707, HDMI input and output (including audio and video) does not respond!
Fault description: My KRELL 707, HDMI input and output (including audio and video) does not respond! Whenever HDMI input is used, the machine display shows waiting for audio, and the TV shows no signal input. However, the optical front and coaxial input are normal. I found that some 707 users on the forum also encountered this problem. Is it a common problem? How to solve it? Thank you