Connecting 15khz CRT RGB TV via VGA

I found this 20" consumer TV in the dumpster yesterday “FUNAI 20A 1110”. I has SCART and also RGB input from what I can tell.

Now I thought would be easy enough to buy a VGA to SCART adapter and hook it up my HP EliteDesk USDT computer.
But I heard that only ATI cards can deliver a 15khz video signal. My computer only has integrated Intel HD4000 graphics. Will it be able to supply this TV with an image? If not, would it then be possible to use an MXM card such as this one for that purpose?

Intel 15 Khz works with Linux. Might work with Windows, but I couldn’t get it to work, and my primary cards are by Nvidia anyway, which also work without problem under Windows.


Thanks! Which adapter did you use? I am planning to build one myself. Commercial ones with active circuitry seem pretty scarce.

My guess for the preference of ATI cards is that they can be used without active adapter since they also transmit some sync signal or something like that…

I’m using the UMSA from Arcadeforge. The preference for ATI is likely due to compatibility with CRT Emudriver for Windows and they tend to have lower pixelclocks, which can be an advantage. Though probably not for Retroarch.

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Ok, so it doesn’t work. I already loaded a custom kernel with these patches: but still…
The TV just doesn’t detect any signal.
Could you please provide some details of your setup and how you managed to get intel to display 15khz? best regards.
This is the adapter I built: And I do realize, there is a good chance I messed something up while assembling it… I have absolutely no clue how to troubleshoot it. That’s the problem when you just blindly assemble something without knowing how it works. Should’ve just gotten a well proven commercial product.

I use Linux Mint and for testing, the CRT is usually a second monitor. I also managed recently to output 15 khz via the Intel GPU with my Surface laptop under Windows 11 via CRU.

I never quite understood what exactly these custom kernel patches do. You can boot with a Linux Mint install USB stick then use the display settings to detect the CRT as a second display. With the UMSA, there will be incompatible PC resolutions listed. It’s necessary to set up modelines via Xrandr.

Intel has typically high pixel clocks, so you need to set up something like 1280x480i, or 2560x240p etc. This makes the desktop unusable by default, but this is why I don’t use Intel or have the CRT as primary monitor :smile:

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Well, xorg seems to recognize something

Could you please provide your modelines?

I never quite understood what exactly these custom kernel patches do

Well it’s supposed to add the capability to output 15khz. But I just don’t know if intel is capable of it hardware wise…
What would be some common 15khz resolutions that can be displayed by a regular consumer TV?

You can try to add the following to the VGA Output via xrandr (or whatever method you’re using) and set the CRT to use that resolution.

“1920x240” 39.980 1920 2096 2296 2544 240 243 246 262 -hsync -vsync
"1920x288_50 " 37.44 1920 1968 2160 2400 288 294 302 312 -hsync -vsync
“1920x480i” 40.06 1920 2096 2296 2544 480 486 494 525 interlace -hsync -vsync

“2560x240” 50.31 2560 2624 2880 3200 240 244 252 262 -hsync -vsync

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Thanks!! It fucking works!!!
Well, kind of… It will only display the 1920x240 resolution and I really want to use the screen for desktop use - ie. watch old movies.

Here’s another TV I got. Also works.

So intel just doesn’t support a pixel clock that low… Could installing a card such as this one mitigate the issue? Or is there a way to make the image less scuffed? I guess retroarch kinda adjusts the picture automatically with this switchres thing?

Only the first is weird though. No picture at all with the rest, or rolling, whatever? Best you can do resolution wise for navigation is probably something like “1280x576” 26.5 1280 1320 1448 1672 576 586 596 625 interlace -hsync -vsync

Stretching with movieplayers shouldn’t be really a problem. Probably also possible to stretch the desktop properly with scripts at start or whatever, but if you can’t get interlace…

I’ll ditch this small computer. Would’ve been nice to have this small pc work as a retro PC - too good to be true. Life isn’t fair :frowning:
It was a waste of money I bought it for just that purpose and it’ll propably end up catching dust now.
Good thing though I have an old AMD 64 X2 tower PC with integrated graphics lying around. If the graphics don’t suffice I can just pop any general purpose GPU in there.

I guess any ATI card will work fine? @Jamirus

Maybe? I have no idea about possible problems with your adapter and the extent of pixel clock variation on Radeons. You might as well just get an old notebook with something like an 2xxxx-4xxxx card if you’re only watching SD movies. Oldest hardware I currently have and use for 15 Khz is an old thin client where I could put in a Radeon 3450 and use XP with. Clocks on old Radeons are around 7 Mhz which allows for 640x480 no problem.

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Ok. So does your setup also support other resolutions than 640x480?
The 30hz are a bit too flickery for me.
Under linux I read this CRT switch res will be able to automatically adjust the right frequency for the rom being played.

Maybe those Linux patches can do some improvement, but flicker is just a thing with interlaced on standard TVs. If you run progressive resolutions, sure, it’s different. CRT Switchres generates the resolutions automatically, yes, you may still need the mentioned ini there or things won’t be correctly centered etc.

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Hello again. I got an ATI 4850 and tried outputting the 640x480 resolution to no avail.
Could you please provide the proper modeline?