Fixed now...
I spoke too soon in the previous post. While Dynon's support has been excellent, the problem turned out not to be a fault in the Skyview.
To go back about three months, I've had a constant `bzzt....bzzt...bzzt' sound in my headset repeated at exactly one second intervals. Both pilot and co-pilot sides were affected. The sound level stayed constant despite adjusting the intercom squelch and volume knobs, and was unaffected by the transponder, radio, autopilot or lights. At first I thought the sounds were related to the flashing warning signs on the Dynon, but later realised they were exactly timed to the digital clock on the display. The noise would start as soon as the boot sequence got to `starting network manager'. If I unplugged the GPS antenna from the AV5000 module so that the system couldn't pick up the time signal from the satellites, the clock would not appear and neither would the noise. Dynon initially thought it might be related to the transponder, but neither disconnecting the transponder, the EMS, or anything else seemed to make any difference. If the clock was active, so was the noise. The only way to get rid of it was to disconnect the GPS antenna, which wasn't really a good solution. However, flying with the noise wasn't an option either as it was as irritating as a dripping tap.
However, I got lucky this afternoon when a local electronics guru happened to be at the field. He spent a couple of hours trouble-shooting the system, checking the Skyview settings, the radio, tracing the wiring diagram, pulling pins, etc, until he eventually discovered that the noise was apparently being generated by interference between the music jack wires and the tunnel harness, which runs to the ADAHRS mounted in the tail cone. When the GPS antenna was connected, it appears that EMF generated in the network cable was being fed into the audio wires that run close to the cable in the tunnel, and was therefore audible in the headsets. Disconnecting the two audio wires fixed the problem. It was a simple solution, but tracking down the cause has been a very frustrating exercise. Glad it's been fixed now.