Rock Pi 4 c , no HDMI signal after ok password

[weecee]

Hi,

 

An old problem, since I got the board which is 4C. Not a + - or whatever but the plain C.

 

Symptoms:

1. HDMI worked randomly, maybe every 10th...15th boot lead to a working system, or rather to a visible HDMI-connection. But now switching on-off does not help at all.

2. Quite often one can get the board booting to the point where it asks for the password, and after clicking ok, it switches the screen off, and won't return. So the telly says that "no signal".

3. When switching on the board the tv set sees that there's someone on the hdmi port, and shows the booting sequence, and finally goes to Armbian's graphical mode asking for the password. Click "ok", and in 10 sec we are in the "no signal" -state.

4. And now guessing; when the board loses its connection to the tv set once, it will keep the hdmi feed down and it can not be woken up but by re-booting the board? Is there such a two-way feedback in-built? I mean, if the board does not recognize the tv, then it's stops sending video signal?  And how to switch off this feature if there's one? Btw, I'm not a computer hobbyist so knowing not much about these, maybe just a (ab)user. I've been writing about this "feature" earlier to many platforms but no answer whether Armbian is programmed so that the board-whatever needs to "see" the receiving set all the time to keep its hdmi signal alive. This has 5.10.63-rockchip64 - kernel, the last one to have a working sound with this board. Well, not even sound now...

 

And yes, this has a miniature hdmi -connector which maybe the culprit partly. It's very weak both mechanically, quite loose cable connection. If you twist-press the cable it may help to get the screen on, but now even this does not help anymore. And it's been tested with half a dozen cables so that's not the reason either.