Grub problems with hdmi adapter in hpt620

[Bigjohn57]

I have a hpt620 thin client which I use with a Panasonic TV as monitor via a display port to hdmi adapter
The systems has Linux and windows systems on it and until recently worked fine using grub bootloader
However the system bootloader has stopped working.
One system does load eventually after 30 second delay and a horizontal screen of coloured bars!
I cannot use F10 to access bios.
I have tried a brand new adaptor with no change

If however I use a VGA to HDMI adapter I get the full boot screen and can select any system as normal
BIOS settings are also available!?
Has anyone any idea how to solve this problem

[SMG]

I have a hpt620 thin client which I use with a Panasonic TV as monitor via a display port to hdmi adapter
The systems has Linux and windows systems on it and until recently worked fine using grub bootloader
However the system bootloader has stopped working.
One system does load eventually after 30 second delay and a horizontal screen of coloured bars!
I cannot use F10 to access bios.
I have tried a brand new adaptor with no change

Welcome to the forum, Bigjohn57.

If you have no image when using the DP port, but you do have an image when using the VGA port, it sounds like there is a hardware problem with the DP port. An issue with the port can be separate from an issue with the adapter you attach to the port. That may be why the new adapter did not work.

[Bigjohn57]

Thanks for the reply.
How can I diagnose the problem as the hdmi port does work to a degree as per my initial post.
When I have attempted boot repair programme it fails to complete and indicates that it is something to do with a Mac set up in the bios.
There is obviously an output from the adaptor but the boot screen is obviously being blocked initially before the time out on the grub bootloader ends and the system boots up into a single system!?

[SMG]

How can I diagnose the problem as the hdmi port does work to a degree as per my initial post.

Your description indicates your computer does not have an HDMI port. Your computer has a DP port and a VGA port. You are doing a conversion in between the computer and the TV with your adapter. That conversion does not change the fact the physical hardware on your computer is still DP or VGA; it is not HDMI.

When I have attempted boot repair programme it fails to complete and indicates that it is something to do with a Mac set up in the bios.

The BIOS is firmware. You should be able to get into BIOS/UEFI even if you do not have an operating system installed. Booting to the firmware (BIOS/UEFI) happens before grub is called.

I thought F10 during boot brings up the boot order so one can change it, but not necessarily BIOS itself? I have an older slower computer, so I just watch the screen for it to tell me which key gets me into BIOS. I do not recall for sure which key is boot order and which one gets me into BIOS.

What boot repair program are you running? The one I have seen with Linux Mint usually creates a report even if it is not able to fix the problem. That report usually gives information about the system which is helpful in trying to get things fixed (if it is possible to fix it).

There is obviously an output from the adaptor but the boot screen is obviously being blocked initially before the time out on the grub bootloader ends and the system boots up into a single system!?

What single system is it booting into?

[Bigjohn57]

The system it eventually boots into is the first available in the grub menue
It does not matter what the operating system is.
It will boot into any installed system as long as it is first in the grub boot order.
At present this is Linux mint 20.2

[SMG]

The system it eventually boots into is the first available in the grub menue
It does not matter what the operating system is.
It will boot into any installed system as long as it is first in the grub boot order.
At present this is Linux mint 20.2

Does this mean you are not able to use your keyboard (or mouse) to select something?

It is my understanding Grub is designed to boot into the first option if you do not select an option within the time-frame set in grub.