Horizontal Resolutions on 15Khz 240p Displays

[DuxPrime]

After picking up a PVM to play 240p consoles on through RGB, I saw it was possible to play modern, retro-looking games on these monitors as well. I obtained an ArcadeVGA 5000 to enable analog video output from my PC at a 15Khz horizontal refresh rate.

This works wonderfully when running at any vertical resolution of 240 pixels (duh), and any horizontal resolution less than or equal to 320 pixels. As soon as the resolution is above 320 pixels wide, the screen becomes garbled.

It was my understanding that CRT displays could effectively display any horizontal resolution (e.g., super wide resolutions in Groovy MAME). This is further confusing by the fact that any of my retro consoles, such as the SNES with a 256 pixel-wide resolution, work without issue.

Do I have a fundamental misunderstanding? Or is this perhaps an issue with resolutions in Windows? For reference, the monitor I'm using is an Ikegami TM20-20RH.

[BazookaBen]

Do I have a fundamental misunderstanding? Or is this perhaps an issue with resolutions in Windows? For reference, the monitor I'm using is an Ikegami TM20-20RH.

You shouldn't need the ArcadeVGA at all.

I played BloodStained: Curse of the Moon on my CRT. That game uses the 3DS's resolution, 400x240, and worked out fine. I had to run some older drivers on my 380x though. That was the last time I've hooked my PC up to my CRT. That was running VGA out to a component converter.

HDMI transcoders also work. But depending on GPU and/or transcoder requirements for a minimum pixel clock, you may need to quadruple the horizontal pixel count, or even quintuple. So for games using 3DS native resolution, you'd have to output at 1600x240.

I admit, though, that I'm out of the loop on the current driver situation. I do plan on building a PC dedicated for emulation and low-res indie games on my CRT. It will have an AMD card and probably the CRT Emudrivers.

[DuxPrime]

You shouldn't need the ArcadeVGA at all.

In my case, I do. I have a newer nVidia GPU as my main graphics card, so I needed a dedicated one to output a 15Khz analog signal to my PVM.

I appreciate your response, but it doesn’t address my main question which is: why can’t my monitor display resolutions with horizontal pixel counts greater than 320?

[maxtherabbit]

You shouldn't need the ArcadeVGA at all.

In my case, I do. I have a newer nVidia GPU as my main graphics card, so I needed a dedicated one to output a 15Khz analog signal to my PVM.

I appreciate your response, but it doesn’t address my main question which is: why can’t my monitor display resolutions with horizontal pixel counts greater than 320?

it's not your monitor

You are correct in that CRTs do not care about horizontal dot clock. They will happily display anything as long is the h-sync frequency is within their sync range - even if it means the input signal exceeds the grill/mask's ability to resolve the individual dots

whatever issues you're having are likely a result of incompatibilities within the video card itself or drivers

[Sumez]

Yeah - the monitor doesn't even know about the horizontal resolution. Such a concept doesn't exist in its vocabulary - it's just providing a continuous stream of colors as it crawls across the screen.

So when you're seeing an issue like that, it's a sync thing, most likely related to the 15khz encoder.