So I picked up a mercs pcb off of ebay for 52$ US shipped. Works great. But there's one bizarre thing about it. When it displays certain graphics my tv loses the sync signal. My tv loses sync for a split second when I hit the bomb button. It also loses it at the screen between stages showing the big picture of the dude holding a gun. And the sync is all over the place when I go into the test menu and go into the "object character" test screen. However when I run the video signal into my video capture device the sync is much better and doesn't have these problems. So.....what on earth is causing this issue? I tried swapping the A-board since my sf2 pcb has a compatible cps1 a-board and I still had the same problems occur so the weirdness is caused by either the b or the c board. This mercs board is also pretty darn beat up. I fixed it up as much as I could. I'm just wondering what would cause it to go out of sync like that on my tv.
I assume that you are using a Supergun, if so what type of video signal are you using? RGB or something with a RGB to video encoder (Composite, S-Video or Component)?
yeah I'm using a supergun. And I'm using a rgb to s-video encoder. But the strange thing is my capture card doesn't lose sync and it's capturing out of the s-video signal that comes from the encoder. It's using the exact same s-video signal that goes into my tv. When I go into the "object character" test menu it displays the objects all messed up on my tv (horizonal sync is all over the place) but my capture card displays it fine
Check all of the voltages on the supergun. I'm certainly no expert but I can only guess that the power line which tells the TV what to switch to and expect isn't sending out enough juice, whereas you capture card will be pre set up to look for everything and everything and prepare to sync to it. Also have you tried another TV?
I'm afraid that's just the nature of the beast on superguns. Different TVs and input devices have varying abilities to sync up to signals that aren't perfect for standard consumer video rates. Try a different TV/Monitor. RJ
Is the RGB convertor onboard (inside supergun uses Supergun for power) or offboard (outside supergun uses an external PSU)? Again make sure that your supergun is outputing 5V under load (you can check this by using a multimeter against the 5V and Ground lines, it should be close to 5V as possible +/- 5% max...) Also remember that the SCART (RGB) standard is 0.7Vpp at 75ohms and 1Vpp at 75ohmns for Sync. Most arcade boards will give out between 1 to 4.5Vpp at up to 1Kohm some arcade encoders will clamp this voltage but some don't very well. Your video encoder probably is more tollerent to the encoded differences better then your TV. You can kludge the supergun with pots to clamp the video and sync levels down.
uhm. I'm feeding the video to my tv through s-video. S-video doesn't have any voltage signal to tell the tv anything. The rgb to s-video board is external since I also use it for my super famicom and megadrive. It uses the same psu as what's powering my supergun (atx 2.whatever pc psu). I tried hooking up the video converter to its own dedicated psu and it still does the same thing. So it's not caused by any lack of power. I'm fairly certain that the fault is my tv. I'm pretty sure you're right about my encoder being more tolerant than my tv. This's a really strange issue. So far on this supergun I've successfully run the following games with zero sync issues: ketsui street fighter 2 world warrior raiden dx gunforce neo geo mvs mv-1f Gunforce is a little dark but I'm pretty sure that's just something to do with the pcb street fighter 2 clips a tiny bit of the screen off and raiden dx clips a little bit of one side of the screen off. But this's the first pcb I've had any form of sync issue with. The weirdest thing is that my sf2 board is also cps1 and it doesn't have this problem at all.
Was it you who wrote about a similar thing on SHMUPS forums? This is related to the "overscan" effect (might be incorrect term to use but i don't know what else to use)... here is a webpage about the investigating wich was done before MAME emulated it correctly: http://hornet.homeftp.net/technical/3wonders/ My monitor has problem also with the Mercs intermission screen... but i never thought the explosion effect would have used the same effect because it happens too fast for me to notice any colour changes (thats how it affects my monitor, the sync is still fine, it just removes the colour that goes outside the game area) Mega Twins do also have an explosion at the intro but it happen more slowly so i can notice the difference (loss of colour). Here are some text from the MAME source explaining the effect:
wow thankyou so much! I'm so glad that my board is acting normal I was worried something was damaged with it. I didn't post about it on the shmup forum so that must have been someone else. where did you get that mame text from? I want to read more about this weird issue I don't get any loss of colour. Instead I either get a scrambled sync signal or just lose sync completely.
Strange that Capcom used that effect in the "object character" test screen also, but yes there is nothing wrong with your monitor it's just Capcom that seemed to use a special brand of monitor(s) that handled this effect without problem. This is how the "object character" test screen looks on my monitor: Compared to MAME wich shows the correct colour: The monitors behaves differnt to this effect it seems... i loose colour and you loose sync. The MAME quote i wrote was all there was in the source explaining this effect. Here is a link if you want to study the code: http://www.mamedev.org/source/src/mame/video/cps1.c.html (mentioned almost at the bottom in the source).
Here let me demonstrate for you how it looks on my screen and then when I move around in the object test menu it gets even worse (some parts lose sync 100% and my tv just has a no signal picture) And here's the exact same picture taken with a screenshot through my capture card coming from the exact same s-video signal that's going to my tv in the above picture. even the osd menu on my tv has funny sync when displaying that picture The s-video encoder I bought is just a cheap one from arcademvs.com. It's actually been a perfect encoder up until I got myself mercs. Do you think jrok or any other encoder would be able to handle this problem? Or do you think the encoder has nothing to do with it?
You could try a jrok, but I'd personally e-mail him first and ask. Jamtek's RGB level theory is probably correct, and the encoder has to deal with them to get them to a level your TV will accept. Ignoring your capture card, have you tried another TV?
Umm, we were just saying try another television TO SEE IF IT IS YOUR TELEVISION. We're not saying go out and buy a new TV to replace yours Let us know if you try a jrok - I'd be interested to know whether it sorts it.
