One H3 - HDMI>VGA adapters problems

[f82]

Hello,

I've an Orange Pi H3 board and I should use it on an old vga Acer 15" monitor. Usually with the other SBC and video outputs, I used the usual HDMI to VGA converters that doesn't have an external psu but seems to take the voltage from the 18 pin of the HDMI outputs. With this monitor that is indeed correctly identified by EDID on the adapter and on the Armbian o.s., the screen goes blank and return every few seconds randomly. I measured the PI One H3 pin 18 voltage and it gives out something like 4,6v to 4,8v and I think this might be the problem (?). I remember on the Rpi there was an option to boost the hdmi output and I suppose it increased that. Is there any similar option into the /boot/ files? Or I have to look for an external powered adapter or mod it myself?

Hoping that this is the problem, for example on another monitor the signal is stable enough so it might be this monitor to actually need a stronger signal I can't know.

Thanks for any suggestions.

Bye

[f82]

UPDATE: I tried modding one of the adapters I got powering the 18 pin HDMI line with a 5.0v stable external usb psu and nothing changed so I suppose it's not about the power voltage but something about how the HDMI output is configured. The monitor works perfectly with a VGA video card and I suppose it might have something to do with being an old LCD with old EDID and version. Are there any safe hdmi output options to try?

[arox]

My hdmi-vga adapter also do that, but for me it is clearly caused by EMI : I can trigger it with a piezo-electric lighter.

[f82]

  On 4/15/2021 at 6:40 PM, arox said:

My hdmi-vga adapter also do that, but for me it is clearly caused by EMI : I can trigger it with a piezo-electric lighter.

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Interesting, thanks. I got two different adapters with different main ICs one seems to be better and in fact before their wires didn't get broken it worked for a while. Now I should resolder all the 20 wires on that and it's quite boring and not even sure I'd get the same result as in the past. I suppose something can be done on the boot config files to boost the data signal to somehow reduce these interferences?

Might be a solution to try to shield the adapter with some copper adesive? I've seen some adapters online having that around the whole PCB. Mine didn't have any beside shielded wires.

 

[arox]

  On 4/15/2021 at 6:51 PM, f82 said:

Interesting, thanks. I got two different adapters with different main ICs one seems to be better and in fact before their wires didn't get broken it worked for a while. Now I should resolder all the 20 wires on that and it's quite boring and not even sure I'd get the same result as in the past. I suppose something can be done on the boot config files to boost the data signal to somehow reduce these interferences?

Might be a solution to try to shield the adapter with some copper adesive? I've seen some adapters online having that around the whole PCB. Mine didn't have any beside shielded wires.

 

Expand  

Tell us if you get some improvement. But I think EMI can be propagated by every ground loop in your hardware ...

[f82]

I might try to bridge the external PSU ground attached to the HDMI external adapter ground to a HDMI ground pin wire and see if it helps. I even tried booting without any usb devices, from the same USB PSU divided in two for the HDMI power mod and the Orange PI psu itself sharing the same ground source from the eletric attached psu.

Probably this VGA monitor is more sensible than others inputs.. for example I got a TV with vga input and works as it should.

 

[arox]

I have put a ferrite ring around the hdmi cable (one of those you can find on usb cables). So far I cannot trigger black screen any more.