CRT, VGA, RGB, khz. . . [Got It]

[wizarddata]

Dipping my toes into the retro gaming world with a tv that has component input and an old Asus motherboard that, for some reason, has component out from the onboard Nvidia GPU.

I did get windows installed and a picture onto the TV, but it looked like a dogs breakfast. The problem is my memory is full of nice 1024x768 VGA CRTs. This TV is cool with 480i and the compression in component doesn’t do text any favors.

I’m looking at what it takes to add a 15khz RGB input to the TV and get a compatible signal out of a GPU.

Adding the RGB input is straight forward enough, and as long as I can get the requisite 15khz signal out of my GPU, then combine the h and v sync signals into a composite sync, I should be good to go?

I’ve spent some time with custom resolutions on Nvidia GPUs, so I THINK I might be able to set that manually in conjunction with the correct resolution. It is outside of the VGA spec, though, so I’m not sure.

Even then, the BIOS screen wouldn’t show up, so I’d need to pull out a second display sometimes. Seems totally workable, though

Enter these cheap VGA to scart adapters on eBay:

VGA To SCART Converter USB Video Audio IR Signal Adapter NTSC PAL SECAM For PC...

VGA2SCART VGA To SCART converter board RGBHV to RGBs | eBay

I’m pretty sure the above devices do different things, but in my mind, I’m using these to adapt the 15khz output from my PC into a panel mount scart connector on the side of the TV. This way other scart devices that I play with in the future can also be used here.

Besides the obvious path of just buying a VGA CRT monitor, am I missing a simpler/cheaper way to accomplish this? Any sage recommendations from somebody that has already spent some time down this rabbit hole?

I’m reluctant to buy any more old hardware than I absolutely need to, simply because it’s heavy and takes up space I already have enough shit, but if I’m really setting myself up for failure here let me know

EDIT: Further research revealed that should be able to get 15khz modern nvidia gpu, but only at 320x240. I might go with the VGA2SCART adapter just to make my like easier and go from a custom 31khz 480i resolution down to what I need for the modified TV.

[wizarddata]

I’ve been playing around with software to see what plays nice at 480i. The answer is “not much”. Even RetroArch changed the refresh rate to 60hz and breaks things. Guildwars and vlc play nice, though.

Ordered some db15 connectors to add the port to the side of the TV, should be here next week.

I’m wrestling with either sticking with older hardware or setting up a virtual machine on my main rig with an old GPU passed to it. I’ve never done anything with GPU passthrough outside of truenas, so I’m expecting to. . . learn a lot.

[rrubberr]

My solution was to use an old CRT monitor over a Thunderbolt 3 to VGA adapter.

The benefit is that this works with my modern A5000 GPU, so I have enough horsepower to emulate difficult PS2 games, for example. A CRT monitor will also cleanly support the 640x480 native resolution of consoles like the GameCube and PS2.

Under Linux, all of the CRT monitor’s refresh rates and resolutions are available. And it’s sharp enough to toss a Windows XP VM on, if you’re on a retro kick. This also works great with Laptops; I use the same adapter and CRT for emulation on my 2019 MacBook Pro.

[wizarddata]

I’ve been wary of active conversions up to now, but this old hardware is kind of a pita. I’m guessing there aren’t any latency problems?

[rrubberr]

@wizarddata

I’m guessing there aren’t any latency problems?

I don’t have an objective way to measure, but subjectively there isn’t any latency problem.

If you want native analog out, Nvidia’s Maxwell cards (GTX 980) were the last generation to support it, after which Pascal cards (GTX 1080) dropped it entirely.

[wizarddata]

In moving the computer around and plugging/unplugging things, the Ethernet port is getting flakey. Seems the decision is being made for me

I’ve got an old laptop with VGA out that I forgot about, going to fire that thing up as I’m installing the RGB input for testing. Reasonably certain it’s got more oomf than this old athlon did.

[wizarddata]

I’m getting closer.

Despite my best efforts, I could not get this GPU to output the reported 15hkz via custom resolutions in windows 10. Closest it would get is 19khz.

In Linux, however. . .

That’s the combined h and v sync signals, right around 700mv. Waveform looks correct against what I expected per the internet.

The picture, however:

It looks like it’s expecting a slower sync signal maybe? This changes based on whether I inject the sync signal at a Y port or a composite port, which the internet doesn’t think would make a difference.

I’ve seen vsync and hsync pins n schematics, so my next step might be to inject these sync signals directly to an IC instead of going through whatever happens between port and IC.

[wizarddata]

Just wanted 64 hz instead of 60.

Ngl, this feels pretty good. Only works with the sync signal going into a Y port, but that might just be because of what input I’m on.

Edit: money shot