It sounds like your monitor isn't returning a suitable EDID to report the modes it supports.
Unplug everything from your Pi 4B, including the SD card. Connect the monitor and turn it on. Connect power to the Pi.
You should see a diagnostic/boot screen, which will fail to boot because the SD card is missing. One of the lines on the screen should start "Display:". In that line should be two HPD= and two EDID= entries, one for each HDMI output.
If all is well, you should see at least one HPD=1 and one EDID=OK entry.
If not, try a different micro HDMI lead.
If that still doesn't work, you can edit the cmdline.txt file and force a video mode in there.
Unplug everything from your Pi 4B, including the SD card. Connect the monitor and turn it on. Connect power to the Pi.
You should see a diagnostic/boot screen, which will fail to boot because the SD card is missing. One of the lines on the screen should start "Display:". In that line should be two HPD= and two EDID= entries, one for each HDMI output.
If all is well, you should see at least one HPD=1 and one EDID=OK entry.
If not, try a different micro HDMI lead.
If that still doesn't work, you can edit the cmdline.txt file and force a video mode in there.
Statistics: Posted by rpdom — Sat Sep 14, 2024 8:21 am