Problems with connecting Pi 4 to TV via HDMI

Support
#1

Hi,

I’ve got a Raspberry Pi 4 which I connected to a TV with a micro-HDMI to HDMI cable and it’s almost working, but there are two problems:

  • There are a number of flickering pixles on the screen. Sometimes this starts as soon as the Pi boots, sometimes they appear little later.
  • The HDMI signal is dropped/lost at random intervals. The Pi seems to be runnig fine, no spikes in CPU usage, but the screen goes black like there’s no signal, then it comes back in a second. This keeps going on with (seemingly) random intervals between the blackouts.

First the Pi was in a Pibow Coupe 4 Ninja and I thought that maybe the HDMI cable is not connected properly because of the case so I removed the Pi from it, but that didn’t make any difference.

Details:

  • Raspberry Pi 4 Model B with Raspberry OS (up-to-date)
  • Micro-HDMI to HDMI cable (1.5m) - connected to HDMI 0
  • Raspberry Pi Official USB-C Power Supply

Does anyone know what would cause these problems and how to fix them?

Thanks,
Attila

#2

The basic steps to follow are,
Try a different HDMI cable, if you have a spare cable.
Try a different monitor / TV if possible.

The issue could be with the TV, cable, or Pi. One thing I make sure to do is to turn on my monitor / TV before booting up the Pi. If I don’t more often than not I get a no signal on my monitor. It sucks but it is what it is.
Is this the Official Pi Foundation Cable? It’s what I have been buying and I have had zero issues with them so far.

#3

Thanks for the tips.
This is not the official cable, I’ve got this one: Micro-HDMI to HDMI cable (1.5m) – Pimoroni
And that’s the only cable I have now, so can’t try with a different one.
But I tried to connect the PI to a monitor and it didn’t do the blackouts there but created even more flickering pixels than on the TV. I also regularly connect my laptop to the TV and never had any problems with that.
Does this mean it’s a cable problem?
Maybe I should get an official cable and try that.

#4

It could be the cable, or maybe the Pi? I don’t know how you’d tell without another cable, or another Pi 4. Getting another cable is the easier and cheaper of the two so that’s what I’d do. My gut feeling is its the cable.

#5

OK, I’ll have the new cable in a few days and then see if that works.

#6

The official cable arrived on Wednesday. It’s working fine, no flickering pixels or blackouts with that one.
Thanks for your help.

#7

That’s good to hear, thanks for the update.