So I was wondering after trying out a 53hz Midway game (Mortal Kombat), does anyone know what TVs handle these odd refresh rates well? The TV in my room, a 20" ESA standard CRT would roll the screen. However the 32" Toshiba HDTV in another room worked just fine, though the bottom of the screen was cut off. So does anyone know what TVs are better at handling games that don't run at or very close to 60hz? I've heard Sony TVs tend to be bad. And I've heard that HDTVs are ussually better at handling it. Ofcourse I'm looking for some cheap with S-Video input, and HDTV monitors certainly aren't cheap and neither is a real RGB monitor.
HDTVs are good in this situation because they have worldwide-use digital tuners which can take just about anything you throw at it. You won't find a standard television in North America that will display 50hz, you may not find a multisystem monitor that easily displays 53hz either. What you'll probably need is a unversal transcoder, or a standalone digital tuner or upscanner like the XRGB-2+. Instead of converting the video, I'd try tweaking the game, perhaps the VDP can be overclocked to 60hz without the game crapping out.
Well, you could get this monitor: http://www.billabs.com/bl27cb0p.htm ...and build a cabinet around it. I have one of these damn things sitting in its box in my living room just waiting for my new cabinet to get here. Anyway, what you want to do is look for the vertical refresh rates for the TV's which you are interested in. You might need to dig around in the owner's or even the service manual for the full specs.
can any of the engineering/techs here explain to me in some level in detail, why they'd possibly want to use a 53hz refresh? Is there some sort of technical advantage, or some equation I'm missing?
wouldnt they take a bad loss on mfg the 53hz CRTs tho, or is that something they could easily adjust with stock parts?
How much does that monitor cost? I do have plans to eventually put together my own Mortal Kombat arcade cabinet, or atleast a general purpose jamma cabinet. Perhaps I will invest in some kind of HDTV in the future too.
$549 plus around $160 shipping (unless you can pick it up in GA). Not cheap, but it is definitely the best arcade class monitor available.
Damn... I think I'd be better off hunting for a half decent cabinet with monitor. That or just buying an HDTV, though I'd rather a proper monitor that would fit MK to the screen nicely. But maybe someday when I have a large chunk of cash to burn. =)
8 years old thread Necro time I just repaired a NBA jam board and was faced with the rolling screen issue on my Sony tv and Vogatek supergun. After a bit of research I discovered that the 53hz refresh rate was the cause of this. I tried on my workbench PVM and while the screen does not roll, it is not quite centered. I could not find much information on this by googling beside the ''Just get an arcade monitor'' type of answer. Was wondering if someone here is aware of a work around. Some kind of Extron transcoder maybe?
There is nothing in the form of a Dip Switch or a pot to change the 53hz as far as I can see. I tried several TVs however, regular NTSC tvs, not PVMs and many of them actually keep the image still but it is usually not centered well. I guess one could adjust the set to be centered with midway boards through messing in the Service menu or the pots on the TV pcb. You could hence convert it into a dedicated Midway board display.
The vertical frequency is a consequence of both the hardware (the fixed pixel clock) and how the frame timing is set up by the game. You can either modify the game to change this timing (perhaps with some serious effort you can center the image on your display), or you could add in significant circuitry to do it in hardware, or you could just adjust your display to suit the game. Arcade monitors have simple, adjustable deflection circuits which makes them compatible with a wide range of non-standard video (arcade games generate extremely non-standard video to save on logic). They're compatible with everything because you're expected to adjust them. TVs on the other hand expect broadcast standard video, and in most cases will even attempt to "correct" non-standard video--their circuitry pulls very strongly towards standard scan rates in order to handle poor OTA broadcasts. They also won't allow you to adjust the deflection circuits (or simulated circuits for fixed-pixel) outside of the service menu (or manually inside the case) because it's rarely necessary to. In many cases there might not be anything (within reason) you can do when a display fails to lock to a non-standard rate, but if it does, you can always try adjusting the raster position and width if available. There's no way any sort of video processor can even fix the video frequency without drawbacks (asynchronous input/output = picture tearing, non-standard line count = lines cut or resampling necessary) and I doubt many would be flexible enough to handle able to handle the case anyhow. Generally it's 53 Hz in, 53 Hz out so you'd need a multi-sync anyway.
Some of them do, but not all of them. Some of them output standard 240p RGBS video. I'm able to connect my MVS and my ST-V to my PVM (enough acronyms?) using a simple adapter, and it displays just fine. Machines like the Model 2 and 3 use a form of EGA, which is a very unusual format. I've been trying for years to find a display that will accept the Model 3's output natively, but no luck so far. I believe the Sony GVM line will do it, but they're pretty hard to find. I'm forced to use a convertor at the moment.
What I said really stands, next to no arcade games had standard/compliant video until the mid-90s when they started integrating VLSI 3D chips and no longer implementing their own custom 2D graphics. 80s and early-90s consoles aren't spot on either, but generally pretty close. The ST-V is an obvious exception since it's designed around the Saturn--clearly meant to drive standard TVs, and Sega also got very compliant with the Saturn for digital video compatibility, so it actually has the ability to use exact broadcast timing (either the first system or maybe second after the 3DO). Regarding the Neo Geo (and practically all 2D arcade games)... Firstly, 240p video is itself non-standard, but for the sake of argument "standard" System M 240p works out to 262 lines @ 60.05 Hz. The Neo Geo generates 264 lines @ 59.19 Hz, and it does so to save logic; actually all of the timing in place was designed to efficiently fit into standard logic chips, not to be faithful to broadcast standards. Plus there's the horizontal/line timing; the Neo Geo's are OK, not great, and most other games can be expected to be worse (leading to off center images on a perfectly adjusted "NTSC" display). Secondly, the Neo Geo (like practically all 2D arcade games) generates a pretty poor sync signal, again to save logic--it doesn't have all the equalization pulses of standard video which can cause sync separation issues on non-robust displays (possible deflection distortion at the top left corner). Again most arcade games do an even worse job. Thirdly, the MVS outputs non-standard RGBS signals electrically (like practically all arcade games), they're completely unsuited to driving a TV because they aren't TV level (they're much larger), nor are they impedance matched for a TV nor are the signals really capable of driving a TV without distortion. The RGB DACs are designed around old logic chips which cannot source much current. Low-impedance TV inputs demand lots of current unlike high-impedance arcade monitor inputs. When the chips can't source the necessary current, the voltage can't reach the desired level at the input, and the pixels can't reach their full brightness. Just because your PVM (or any TV) displays arcade video "just fine" (unless you disable the termination resistors there will be distortion) doesn't remotely make it standard video.
Well, I use a small circuit board supergun, and I'm not sure exactly what it does to the signal. It may contain an amp or something to alter the image. But the image is very good - as good or better than any of my consoles using RGB. I don't notice any distortion at all. The PVM may have the ability to accept slightly non-standard video, I'm not sure about that either.
On my bootleg MK1 PCB, the video would have some of the edges of the image hidden off screen. However when I tried it again giving it more +5v voltage (for some reason the voltage on this line was hanging down significantly under 5v) the image fit on the screen just fine. I think my MK2 board may have done a similar thing where one time parts of the top and bottom of the screen were not visible but other things everything fit just fine. And i never adjusted the PVM I have been using. If you play alot of arcade boards then you should probably get some type of professional RGB monitor. Either a PVM or some other company equal, or an actual Arcade Monitor. The Midway games with the odd 53hz refresh rate are a crapshoot with American TVs.
You get more resolution. 53hz is very close to PAL (50hz), and the given timing allows more resolution (254 vertical pixels, instead of 240; but it also uses more memory). You'll have less frames per second (53FPS), but you can squeeze more resolution (more pixels) this way and it's faster than PAL. Perfect for an arcade game with high detail graphics and cinema like animation (it's better than 352x240 NTSC VCD). Also heard Sanyo and JVC NTSC TV's can sync with this timing. You still have to consider it's way beyond NTSC, and in the NTSC world everything runs at 60hz so it isn't recommended. I think a PAL TV would be better and safer, especially those that are PAL 60 capable; and PAL TVs exist with scart RGB so that's even better. Could also find a line doubler that handles PAL and try that with a PC CRT (assuming you have RGB to SVIDEO or CVBS). I personally use an IDC-3000 line doubler, and even though my Genesis doesn't sync with my capture card, it syncs fine with the IDC-3000; it is great with 240P content (no artifacts with flashing shadows etc), but 480i can sometimes show artifacts (flashing Supers on MVSC2 Dreamcast Svideo).
