Another non-booting ROCK64

[mcerveny]

As an experiment try tipping the edge of the metal HDMI connector on the board with the HDMI cable plug end while the HDMI cable is plugged into the monitor and the board is powered up. You'll notice sparking. The Rock64 board needs to be cased and properly grounded which I imagine most tinkerers don't bother with.

The naked board always has such grounding concern :-(

Please DO NOT connect external ground to the board ! If you are not able set the same ground point for all equipment (and antenna) the high current on ground wire can flow between board and other equipment (TV) that can damage anything.

The some effects (like "hotplug" does not work, DDC ("i2c identification")  does not work, CEC does not work ...) are common to all single-ended signaling buses that are affected by ground "voltage differences" due to current flow on ground line.

Recommended power supply is designed as CLASS II (two power pins but no ground). Class II (double insulated) electrical appliance is designed in such a way that it does not require (and must not have) a safety connection to electrical earth (ground).

Checklist

• * power supply CLASS II mark
  
• * problems are in some power supply "reduced" designs without (or fakes) certification marks (maybe some Y class capacitor missing)
  
• * TV antenna connection can be source of high ground (try to disconnect antenna or install antenna galvanic separator)
  
• * disconnect other powered equipment from TV