Just a thought, do you think it could be a PSU issue? The power supply for the monitor comes from a cable that is plugged into the PSU of the computer itself.

Its a Fujitsu ICL monitor by the way.

You got a cold solder joint somewhere or a broken video cable.

Thanks for the response.
What exactly is a cold solder joint?

Thought I'd follow up on this as I finally got around to checking for cold-solder joints today.
I know... 4 years... been quite busy but finally decided to investigate the flickering monitor issue.

Had a look around on the PCB of the monitor and it looks like there were a few cold solder joints around the VGA socket - both on the prongs that secure the socket to the motherboard and the pins themselves.
Have now gone around all these and reflowed them and added a touch more solder. Tested, all working OK.

The monitor has been on for hours now and hasn't flickered once.
I would be happy saying this is solved but I'll keep testing to be sure.

For anyone who stumbled across this issue (maybe 1 in a billion) and thought a cold-solder joint wasn't worth investigating - do it, it's worth a shot.

There will probably be more cold solder joints in the future, so it's probably not a waste 😜

I inspected the entire board and all the other joints looked spotlessly clean and healthy.
Just the ones around the VGA port appeared to have visibly cracked.

At the very least I like to think I've possibly broken a record for thread revival here.
This of course means I will now be spending the next 4 years reliving my childhood after installing all my old games.

Thanks of course to h-a-l-9000 for the pointer 4 years ago.

Gigagator wrote:

I inspected the entire board and all the other joints looked spotlessly clean and healthy. Just the ones around the VGA port app […]
Show full quote

I inspected the entire board and all the other joints looked spotlessly clean and healthy.
Just the ones around the VGA port appeared to have visibly cracked.

At the very least I like to think I've possibly broken a record for thread revival here.
This of course means I will now be spending the next 4 years reliving my childhood after installing all my old games.

Thanks of course to h-a-l-9000 for the pointer 4 years ago.

Thread revival is ok in cases like this one 😉
I prefer it to someone having some problem and then disappearing without ever telling how things ended up 🤣

This bump is moderator approved 😁

Gigagator wrote:

I inspected the entire board and all the other joints looked spotlessly clean and healthy. Just the ones around the VGA port app […]
Show full quote

I inspected the entire board and all the other joints looked spotlessly clean and healthy.
Just the ones around the VGA port appeared to have visibly cracked.

At the very least I like to think I've possibly broken a record for thread revival here.
This of course means I will now be spending the next 4 years reliving my childhood after installing all my old games.

Thanks of course to h-a-l-9000 for the pointer 4 years ago.

If the solder joints were cracked, it almost certainly was due to mechanical stress, not cold solders. Maybe the VGA cable's been strained, someone yanked it by mistake at some point, or something like that. Cold solders would just come loose from the pins, solder pads, etc, without cracking.

There's probably no need at all to worry about the other joints 😀

kaputnik wrote:

If the solder joints were cracked, it almost certainly was due to mechanical stress, not cold solders. Maybe the VGA cable's been strained, someone yanked it by mistake at some point, or something like that. Cold solders would just come loose from the pins, solder pads, etc, without cracking.

There's probably no need at all to worry about the other joints 😀

That would make sense in many ways. That monitor spent many years being mishandled and tossed in and out of the attic and around various rooms.
There is an issue with a faint vertical line on the left side of the monitor but it's barely noticeable most of the time so I can live with that.