Old analogue monitor help?

I think it might be a good idea to scope out the signals as generated from the present board, if only just to see a black/solid colour raster. The older monitors aren't very tolerant of timing being too far off as it can cause overstress in some of the analog drive circuitry which leads to burnt-out components. It's why (in the past especially) even Windows warned you about setting display modes not supported by the monitor being possible cause for damage. Likewise, Commodore PET machines had a "killer poke". At the least, it doesn't sync and nothing shows. At the worst, damage is possible.

Once you have a working signal from the present board and know the levels then you might know better as to what sort of signals to generate (e.g. it could be something akin to VGA with R, G, B, Hsync, Vsync and respective grounds expecting a signal that's about 1V or it could be something more like the EGA/CGA era monitors which used full TTL and expected 5V - and also knowledge about scan/refresh rates/front/back porches and vertical blanking interval).

If not, then hopefully you're able to better narrow down the monitor chassis itself as to the model/manufacture and obtain a spec sheet for it.

It's also good to know if the monitor's actually any good as well. As with any CRT, blown flyback transformers, bad high voltage transistors, failing capacitors, knocked alignment magnets during transportation, problem with colour convergence are potential issues. Unstable high voltage which makes the image "bounce" depending on content also seems to be a common issue. CRTs are a source of high voltages - lots of dangers for the inexperienced newbie. No point building for something that's not functional or can't be replaced either.

Then it comes to the hard effort of actually making something that works. While for other video standards like composite, you can generate a video signal with a single pin, doing so with a microcontroller across multiple pins and getting the timing fine-enough to get the full resolution is hard. It's probably something that an FPGA might be better with owing to the fact you will need to drive the RGB values simultaneously during the image period (assuming you want a colour display). If not, monochrome might be achievable tying the lines together ... but keeping the sync accurate on a controller that might have other tasks to attend to (e.g. other interrupt routines) might not be the easiest way to ensure a healthy signal to a monitor like this. Maybe you can settle for an occasional glitch as long as it doesn't kill the monitor outright.

Unfortunately, I can't really offer any real model-specific assistance in that regard ... good luck with your project and take care! High voltage can be quite a frightening experience, if you survive.

I think it might be a good idea to scope out the signals as generated from the present board, if only just to see a black/solid colour raster. The older monitors aren't very tolerant of timing being too far off as it can cause overstress in some of the analog drive circuitry which leads to burnt-out components. It's why (in the past especially) even Windows warned you about setting display modes not supported by the monitor being possible cause for damage. Likewise, Commodore PET machines had a "killer poke". At the least, it doesn't sync and nothing shows. At the worst, damage is possible.

Once you have a working signal from the present board and know the levels then you might know better as to what sort of signals to generate (e.g. it could be something akin to VGA with R, G, B, Hsync, Vsync and respective grounds expecting a signal that's about 1V or it could be something more like the EGA/CGA era monitors which used full TTL and expected 5V - and also knowledge about scan/refresh rates/front/back porches and vertical blanking interval).

If not, then hopefully you're able to better narrow down the monitor chassis itself as to the model/manufacture and obtain a spec sheet for it.

It's also good to know if the monitor's actually any good as well. As with any CRT, blown flyback transformers, bad high voltage transistors, failing capacitors, knocked alignment magnets during transportation, problem with colour convergence are potential issues. Unstable high voltage which makes the image "bounce" depending on content also seems to be a common issue. CRTs are a source of high voltages - lots of dangers for the inexperienced newbie. No point building for something that's not functional or can't be replaced either.

Then it comes to the hard effort of actually making something that works. While for other video standards like composite, you can generate a video signal with a single pin, doing so with a microcontroller across multiple pins and getting the timing fine-enough to get the full resolution is hard. It's probably something that an FPGA might be better with owing to the fact you will need to drive the RGB values simultaneously during the image period (assuming you want a colour display). If not, monochrome might be achievable tying the lines together ... but keeping the sync accurate on a controller that might have other tasks to attend to (e.g. other interrupt routines) might not be the easiest way to ensure a healthy signal to a monitor like this. Maybe you can settle for an occasional glitch as long as it doesn't kill the monitor outright.

Unfortunately, I can't really offer any real model-specific assistance in that regard ... good luck with your project and take care! High voltage can be quite a frightening experience, if you survive.