Sanity check for my hand tweaked crt_range0?

[rogerxyz]

Hi everyone! I was previously using generic_15 with my consumer NTSC TV, a Sony Trinitron Sony KV-20FS100.

Up until last night I had 3 or 4 modelines that would lose vsync, rolling vertically. I did my best to grok the guidance in various threads about tuning in your monitor range, and I came up with something that works well now. But I'm not an expert, so I thought I'd just share and get another pair of eyes on my range. If I'm doing anything dumb here or missing possible improvements I'm all ears. Or maybe it's fine

monitor "roger", "Sony KV-20FS100", "4:3"
        crt_range0 15625-16300, 57.3-65.00, 2.000, 4.700, 8.000, 0.064, 0.192, 1.024, 0, 0, 192, 263, 448, 526


I found that this NTSC TV was really not up to displaying anything at 50Hz, which makes sense but I've also heard some contrary advice on other threads, so maybe I'm missing something. Started with generic_15 and tweaked H and V frequency ranges, adapting the max scanlines as required, and touched nothing else.

Thanks and I'm pretty happy to be able to play those few games that gave me trouble before (Revolution X, Atari Star Wars, lookin' at you) 

[buttersoft]

While there's nothing inherently wrong with what you've typed out, that range line has NTSC pretty much right in the middle. If you want to use 50Hz you need to expand things for that to use PAL modes, i would imagine? Something more like...

crt_range0 15625-16300, 48-65.00, 2.000, 4.700, 8.000, 0.064, 0.192, 1.024, 0, 0, 192, 288, 448, 576

Assuming your TV can handle that, which it certainly should given it's a flat-screen Trinitron.

[rogerxyz]

Thanks buttersoft! Just the kind of sanity check I was hoping for.

Assuming your TV can handle that, which it certainly should given it's a flat-screen Trinitron.

Well, see, that's the thing. For some reason or other, my set seemed unable to sync on anything lower than around 57.5Hz. I had generic_15 installed and about 3 of the modelines that dipped under there would roll vertically.

In fact I had read on other threads (probably also written by you!) that I should expect my set to be able to handle 50Hz. Is there anything I should try with the CRT chassis or the GreenAntz transcoder that might give me better hope of getting stable sync at 50Hz? Composite sync is off, I'm letting the GreenAntz combine sync.

[buttersoft]

Hmmm, i wonder if it will work in bands. So, it works at ~60Hz, and hopefully ~50Hz, but not everything in between.  You should at least try a 50Hz mode PAL mode at 288p/576i via RGB, i reckon.

Do you have a way to adjust vertical sync? I see both sync polarities are set as negative, but what does VMM show they are? (open VMM > type "modelist import" > type "modelist list" > look at the sync polarities). Can you add or adjust resistors or anything else?

[Zebidee]

Buttersofts advice on the crt_range is good, for PAL interlaced you need 576 active lines (288 progressive), so edit yours to be more like his (especially the numbers in bold).

I've run arcade syncs into countless consumer TVs, most of those TVs supported both PAL and NTSC, and I often find a "dead spot" between around 53hz to 58hz, give or take, even some of the more expensive brands. It is essentially the no-mans-land between NTSC and PAL, TVs were often not designed for it, and sometimes have trouble syncing. Sorry if this is contrary to what others have reported, but this is what I've found in the real world.

I've gotten around this before by writing custom monitor presets with two crt_ranges, "crt_range0" for a range around 50hz ("PAL") and "crt_range1" for a range around 60hz ("NTSC"). There really isn't much good reason to go below 50hz. There are some examples of multiple crt_range sets defined in the default monitor.ini file.

However in some cases, TVs handle the entire range from 50-60hz and will work with the default generic_15khz monitor presets. So start with the generic_15khz, and work from there.

Worth noting that many of the TVs I've used were in Australia, which is also where Buttersoft is. Pretty much any TV sold into the Australasian market would support both NTSC and PAL. Mostly true where in the Asian markets too as far as I've seen. However, some TVs sold into the North American market may be designed for NTSC only. So keep that in mind.

[rogerxyz]

WOW!!!!! Two bands!!! Okay, this makes perfect sense now. Going to try it, thank you both so much for your continued brilliant advice.

This being North America, I think you may be right about no thoughts given to supporting PAL, so I'm not holding out too much hope but hey, maybe I'll get lucky!

[buttersoft]

I would have thought a TV would just sync all the way through from 240p/480i at 60Hz through to 288p/576i at 50Hz, but yours apparently doesn't. As Zeb notes, maybe North America never needed PAL modes so no one bothered. Let's see if it works trying discrete modes where they're supposed to fall...

[rogerxyz]

Well, I think it's not to be, I added the range from the 'pal' preset to my existing 60±3Hz range, and none of the 50±1Hz modelines generated would hold vertical sync. I'm not too bothered, as my goal was just to find a working range and prevent GM from generating non-syncing modelines. I have an okay assortment of progressive and interlaced modes that will probably serve me just fine.

More importantly, this was very illuminating. I wouldn't necessarily use this as definitive proof about all TVs manufactured for NA, but I think the theory about zero PAL support is quite likely. If anyone else in USA/Canada has a consumer CRT TV that will or will not sync on 50Hz, I'd be curious to hear some more data points. Thanks all around!

[mrchrister]

I did some research on this a while back and in 95% of cases you're out of luck with NTSC CRTs supporting anything lower than 60hz. There are some rare cases where a NTSC-U CRT would display 50hz PAL signals in black and white. Apparently you can mod those to RGB to get color at 50hz but it's unfortunately not very common. My JVC D Series can't show 50hz or even 57hz. My 2030 PVM does 50-60hz flawlessly.