I have the following setup: plasma TV Panasonic TH50PY800, AV receiver Denon 2313, RaspberryPi, Sony BluRay player, cable box from UPC Romania (Cisco 8485HD DVR). Initially the cable box and the RPi were connected to the received and the receiver was connected to TV. This worked for about a year and a half and then the cable box started having problems talking to the receiver (the receiver did not detect any signal on the Cable HDMI input). After one or more on/off, on/off they were working again. The situation degraded over a month or so until they stopped working together.
The Cable HDMI input on the received no longer works with any other device (I plugged in the RPi or the BluRay and nothing), the cable box no longer works in another HDMI input in the receiver, although the HDMI inputs work ok with the BluRay or RPi.
I connected the cable box directly to HDMI2 in the TV (and optical connection for audio from TV to receiver). This worked ok for about 6 months and yesterday while watching some show from cable, the TV lost its image and audio. Turned off/on the cable box and it worked again. Then today in the morning the TV lost its image and audio again. Repeated on/off on the cable box did not help. I moved the cable box from HDMI2 to HDMI3 and everything worked. I moved the cable box back to HDMI2, nothing, the TV does not detect any signal. I moved the receiver from HDMI1 to HDMI2, still nothing, so I guess the HDMI2 in the TV is lost.
Is it possible that the cable box damages the HDMI ports? The weather was fine these days so I guess there was no surge from a lightning and the HDMI port in the receiver went down in a month, not suddenly.
At this moment I have no surge protection on the coax cable that enters the house.
How or why it is causing the problem can be very difficult to track down - damage from an overvoltage caused by lightning getting in to your system via a cable/sat box is usually a bit more terminal for the device which takes the hit.
I have seen an HDMI interface designer here in the UK scratching his head trying to work out why some Source/Sink combinations suddenly stop working - he was discussing the possibility of some form of 'memory' rather than actual damage causing the issue.
I would replace the DVR or risk running out of working HDMI sockets.
Octava Inc. 'Factory Direct' Multi-cast HD over LAN.