MiSTer FPGA Forum

Hello all. I've just put a Mister together with the analogue board on top, hoping to get 15.6kHz RGB for a regular 4:3 TV over SCART. I picked up a recommended VGA -> RGB SCART cable from amiga.store, but when I connect it I just get a black screen. It flickers on startup but I have yet to see the menu on the CRT. It works fine over HDMI, and I've got it online and updated.

In the Genesis core I can see the TV flicker for a split second when it starts up. If I enable Scaler FX settings I can see scrolling - as you'd expect from a set that can't support 31.2kHz. If I plug the VGA cable into a TFT monitor it mirrors the HDMI image, so I know the VGA port is active, but it's obviously >15.6kHZ. The monitor reports that it's 720x240@60, so no surprise that the TV doesn't like it.

In the mister.ini I've got
forced_scandoubler=0
vga_scaler=0
direct_video=0
vsync_adjust=0. I've tried setting this latter to 2, no difference.
I've also tried composite sync, didn't make a difference. I've tried putting a jumper over VGA PWR for both 3.3V and 5V (assuming the centre hole is ground), neither seemed to do anything.

If someone could take a glance at my mister.ini that'd be really appreciated, I'm at the limits of my knowledge here: http://pastebin.com/5EsBcGyn

Is there a way to force 15.6kHz RGB on the menu? Or globally? Pardon my ignorance, I've read a bunch on this topic but obviously I'm still learning.

Are you using this cable?

http://amigakit.amiga.store/scart-minim ... rrency=GBP

Does it have a 470 Ohm resistor on the sync line? Because if not, you shouldn't be using it. --> https://www.retrorgb.com/beware-of-mist ... ables.html

Just wanted to mention that to get the first question that came to mind.

Just to add, you want to always check the scart cables if there a Resistor on the Sync Line.
The MiSTer IO board puts out TTL level sync which is fine for commercial broadcast devices but comes in too hot for consumer grade devices.

Always do your due diligence and make sure there 470 ohm resistor on the sync line, its easy to open the scart head and take a look.
If you know how to solder, it's easy to add a 470 ohm resistor to the Sync line.


Here an article if you want to read about it

https://www.retrorgb.com/beware-of-mist ... ables.html

use this video mode to display 240p correctly on a CRT:
video_mode=320,8,32,24,240,4,3,16,6048

Or you can create an additional ini (mister_alt.ini)with this video mode to use like a secondary mode if the primary use is a LCD screen.

First up, big thanks. I've got a bit of time now so picking this up again.

Yes, it is this cable: http://amigakit.amiga.store/scart-minim ... rrency=GBP

I had tried the MiSTer on two consumer SCART CRTs, a Panasonic from the early 90s and a Samsung from the early 00s. Both showed the same issue as detailed above. I decided to give it a last shot on a tiny little 9" portable SCART CRT from the late 90s (brand "Roadstar", I'd never heard of them) and to my surprise the image displays fine. If it was one of the other two I'd be happy to move on, but the little one is too small and its colour reproduction is poor.

So, I've soldered the resistor on the SCART sync pin. I've checked it with the multimeter and it's actually 400 Ohm but I'm assuming that's within acceptable parameters. It makes no difference to any of the TVs - the little one still displays as it did, the others don't.

I'm assuming, given the results above, that the video mode must be setting itself correctly, but there's something else about the cable that isn't right?

That resistor is just a sort of safety measure and that's probably only for some more sensitive RGB devices. It shouldn't really make any difference as to whether you see something or not.

That AmigaKit cable is described as "Important Note: This product is only meant to be used with a Minimig motherboard. It will NOT work with any other electrical items.". It's probably old description from Minimig (it's a different board from MiSTer) times and it might or might not be relevant. For example, I'm using a cable for MiST...and it works, but not with all cores.

Seems you're handy with soldering, so you might want to make your own cable - or check this one is wired properly. There was a schematic somehwere. You can also buy a ready made one, like this; https://ultimatemister.com/product/rgb-scart-cable/

Another solution is this kind of converter UMSA and its equivalents on ebay, look for "VGA2SCART" there.

It could be also something trivial in the config or TV setup. I had a look at your config but it seems ok - but I use direct video, so am no expert on the I/O way. Maybe somebody else has other ideas.

I made a cable to a schematic I found online, and didn't get anywhere with it - could be I screwed up but I remember double-checking each wire. So I decided to buy one. The reason I bought the Amiga cable is that I'd seen others recommend it as compatible and correctly wired. I'd have bought one of the cables you linked, but they're only available on backorder. I've got enough experience of cottage-industry tech manufacturing to know that backorder can mean a very long wait, so I decided against, but if someone else says that backorder on that site just means a few weeks then I guess I'd buy a second cable.

I do have a HDMI->VGA converter though, and have tried it out - do I just change directvideo to 1 in mister.ini and ensure there's composite sync? I've tried this and I get nothing on the TVs. No flickers, no 576i to 480i with the PAL set's 50/60Hz changeover, nothing.

I had to set composite_sync to 1 for it to work