Hi all,
I’m trying to connect a Jonsbo D8 8-inch external monitor (1280x800) to my RPI4 running DietPI 9.8.
The monitor is detected properly by my laptop running Fedora Linux. Connecting to the Pi however doesn’t give any signal. I have succesfully used the hdmi output to my amplifier for audio earlier.
The cable i’m currently using is a new cable i’ve ordered from Amazon, it’s micro-hdmi to mini-hdmi. I have no other devices i can test that with other than the RPI4 and Jonsbo D8.
A few config tweaks i have tried:
hdmi_safe=1
config_hdmi_boost=5
hdmi_force_hotplug=1
framebuffer_width=1280
framebuffer_height=800
So far none of the changes have had any effect. I’ve tried hot and cold rebooting the RPI4, re-inserting the hdmi cable after boot, and powering the display on and off.
Does anyone perhaps have any suggestions what else i could try to get a signal on the monitor?
Hello, I’m no specialist, nor experienced in this.
Did you try the Pi with cable on any other screen/monitor? Did you try a different cable? Or a small adapter to regular HDMI?
Your cable could be faulty. Not sure if Rpi is always fine on every screen.
I hope you’ll find the solution!
you can check different display settings within dietpi-config. Maybe this helps
Thanks for the suggestions guys. I decided to return the monitor since it felt a bit risky to order more cables and potentially be stuck with a monitor i couldn’t use. Better safe than sorry, so to speak.
Next time i’ll try a monitor i will probably order one that is known to work well with the rpi4, just in case. 
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I know I’m a bit late here, but I happened to have that same Jonsbo monitor too and this is how I made mine work:
disable_overscan=1
hdmi_force_hotplug=1
config_hdmi_boost=9
dtoverlay=vc4-fkms-v3d
I’ve verified that this works with everything from the original Pi to Pi4.
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