A question about sync range of NTSC TVs and RGB mod vs Ypbpr transcoder

[brandon]

I'm looking to buy a display for a 15khz GroovyMame project and have a question about the sync ranges of NTSC TVs.  I've heard that a TV isn't always as forgiving as an arcade monitor for modes that are too far outside of say, 58-62hz.  Any way to test this BEFORE doing an RGB mod? Will a SCART>YPBPR transcoder give me an idea of what the TV will do before I mod it or does it behave different when syncing RGB vs component?  I'd hate to go to the trouble of RGB modding only to find out it's display abilities are extremely limited. 
I definitely want to play the Mortal Kombat games and I've heard they can be problematic.

[buttersoft]

Any CRT TV from about 1990 onwards will decode and sync to both NTSC and PAL. This means ~49Hz to~62Hz vertical scan. If your TV has YPbPr inputs, it’s almost definitely like this. Earlier than this, you may have a region-specific TV. A lot of these would still sync to the same vertical range, or nearly so, but did not have any way to decode the colour signal from another region. Either way RGB does not encode colour, and YPbPr does not encode colour in a region-specific way, so you should be fine.

The TV will sync the same way whatever the signal, composite sync is composite sync in this case, whether carried by a separate wire in RGBS, or alongside the brightness information on the Luma/Y line of YPbPr. The caveat in this example is that you must use a 1:1 transcoder. A lot of signal converters will take HDMI, say, and turn it into composite video – you can feed in a 1080p signal, or whatever you like, and it always comes out at 480i/15kHz like sausage meat. Probably in NTSC/60Hz format every time. A converter having a SCART plug does not guarantee anything.

A 1:1 RGB-to-YPbPr transcoder takes whatever RGB (via VGA plug, SCART plug, etc) signal format you input, and outputs YPbPr in the exact same format; so, as a GroovyMAME-related example, 2560x240@59.97Hz remains exactly that.

YPbPr is very, very close to being as good as RGB, assuming you get a transcoder capable of producing good colour. I don’t know enough about what’s out there to recommend any particular model, but there must be threads on good quality transcoders on the shumps hardware forum, so you could search on there. If you’re going to get a good YPbPr transcoder, you can certainly test for 50Hz capability, and you may not need to RGB-mod the TV at all, though personally I have an unrequited desire to tinker with things so I understand you may want to regardless.

I hear this one is good for the price, though you will probably have to open it and dial the colours in - https://www.ebay.com/itm/NEW-SCART-RGB-to-YUV-Component-Video-Converter-Scaler-/221156873851

Lastly, MK. MK is a pain in the backside. Search the GM subforum on here, because I’m not sure anyone has come up with a good solution for MK.

[brandon]

Thanks Buttersoft! I appreciate the detailed reply. I actually read your crt emudriver/GM guide the other day. Lots of great info.  I thought about just converting a TV with a universal arcade chassis but I've heard mixed opinions on those and I'd like to retain the TV function for consoles if possible.  MK isnt a deal breaker for me so if I have to make compromises there I'm ok. If only I hadn't sold my 27" tri-sync monitor al those years ago.  Thanks again for your time.

[buttersoft]

Yeah those universal chassis seem to be a mixed bag. I've seen some that work fine, and others that are just terrible and really weak no matter the tube you try them on. It may be that they're getting worse through time as demand goes down, IDK. An RGB-modded TV is going to work better, IMO.