MiSTer FPGA Forum

I don't really even know how to explain what is happening clearly, it's like over time the analog video out on my MiSTER stops working. I output to a splitter which lets me select between multiple VGA outputs. On one setting, it goes to a 31 khz CRT VGA monitor, with a native refresh rate of 70 hz. The other setting runs to a cheapo VGA->SVideo converter which then runs to a SD NTSC CRT Television. I usually leave the switch to go to the CRT TV, only very rarely switching over to the VGA monitor.

What happens is that the CRT TV will display fine for several days. I can play games, no problem, on multiple cores. Then, if I go a few days without using it, when I return, it's like it can't sync with the TV anymore. Same settings, hadn't changed or updated anything, it just suddenly doesn't work. The little VGA converter will just display a blank screen, or an image shifted in a direction, or sometimes a green tinted image. Sometimes it'll display an image that is too blown up, like it's only displaying a corner of the total screen. What is weird is all these issues have stable images, the image doesn't roll or jutter, it's just as though everything is shifted in a direction or blown up or tinted.

Obviously the VGA converter is busted, right? Well I don't think that is the problem. I actually have dozens of this exact same converter for various reasons, and swapping between other ones doesn't make this problem go away. I even bought a new one from ebay and same problem. I switch over to the CRT Monitor, and the problem persists. Sometimes I get strange video problems, like the static mister screen on boot will have the entire image shifted to the left, even on the VGA monitor. Or I'll load something like a 32X core, and I'll get an image where only the red and green color channels are shifted to the right, with the blue color channel shifted to the left.

When this kind of stuff happens, I eventually have to resort to popping the SD card into a reader and fiddling with the ini settings, turning things off and on until I finally get a stable picture again. And then everything will be fine again for a few days... until I go a few days without playing and everything starts up again.

To clarify, I'm using an Analoge IO board, running a VGA cable to a switch box, which is connected to a VGA cable running to a monitor, or a VGA cable running to a VGA ->SVideo converter, running an S-Video cable to a SD CRT TV. And, just to be sure, I've also tried running without the switch box in the middle.

I'm not even sure how to reasonably diagnose the problem, and the symptoms are scattershot. Is this a direct video problem? A sync on green problem? Any ideas on how to begin tackling this?

For the best compatibility and lowest latency you should pick up the "active s-video adapter" designed specifically for MiSTer, and then set up an alternate .ini file with the appropriate settings for it. They're around $30-$35 and sold by a few different entities online. If I understand your current setup correctly, it seems like your .ini is set to line-double all the 240p stuff the MiSTer is generating in order to be compatible with a VGA monitor, but then it's going through a VGA to s-video converter designed to cut that signal back down to 240p. If that's correct, it just adds unnecessary steps, latency, and possible signal conversion problems to your setup. In my setup, I have different .ini files set for HDMI output, S-video output (for use with the active adapter) and VGA output. I can switch between these alternate .ini's on the fly by pressing a button combination on my controller, or by selecting them from the main menu. You may want to consider a similar setup

How is your svideo converter getting its 5V power? Is the 5V power jumper on your I/O board set?
I had a SVideo adaptor that only sometimes took power from the VGA cable. It was a defective unit. That could be the case for you.