Groovyarcade works with 15khz monitor, actual games don't [NVIDIA GeForce 8100]

[barryabrams]

I've spent the day setting up my monitor, a computer, and my cabinet, and I got to this point: I've got groovyarcade running off a pen drive, and I've got it so that it defaults to a monitor profile that works for me (just the basic VGA 15khz one... the second on in the list). The monitor I'm using is a 19" Wells Garner. It loads AdvanceMenu, and I can cycle through the list of available roms. When I start one of the roms, it will load it, but the monitor will go out of sync, like it's expecting the monitor to be 31khz. Hitting escape key brings me back to AdvanceMenu, at it displays as it should.

Is there some sort of setting I need to set to mame knows I've got a special monitor, or something? 

[Endprodukt]

Check the vsync and hsync pots. Maybe they're set to a range that doesn't support many games. Start a game and turn the pots until you have a stable screen. You may find a sweetspot that works for the games in mame.

[barryabrams]

I just went out to the garage and tried what you suggested with the vsync/hsync pots, which  moved the flickering around, but it wouldn't settle on anything. And, when I'd exit out of the game, advancemenu would be way out of sync.

Here's a video of what's happening.

[barryabrams]

I logged into the linux desktop and opened the command line. I'm able to launch groovymame (without indicating a specific rom), and the list mode stays in sync. Whenever I start a game, it does the same thing as in the video. It seems as if switchres isn't paying attention and is trying to display the game at 640x480 or something.

[Calamity]

Hi barryabrams,

When in AdvanceMenu, press Escape so you exit to gasetup. In gasetup, select Video Setup, and choose Generic 15.7 kHz. Then try those games again.

[barryabrams]

Gave it a try, and it's doing the same thing. I also tried the Arcade Monitor 15khz down the list, and all of the wells-gardner ones. With a few of the WG ones, advancemenu won't be in sync, so I something is happening, it just seems like groovymame itself isn't using the monitor settings.

[Calamity]

GroovyMAME must be using the settings. It could be your monitor has a very narrow horizontal frequency range. The sample games are a bad test case because their frequency is badly reported by MAME (IMHO) so 256@60Hz pushes the frequency too high. Those games probably run at 55 Hz.

Please test World Rally at the end of the list. That one reports a reasonable refresh. Then, with that one on screen, move your H-Freq potentiometer slowly until it syncs.

If you're using a J-PAC, try unplugging and plugging its usb/ps2 connector while the screen is out of sync.

To make sure GroovyMAME is picking the right settings, you can run it from the desktop, open a terminal and type:

groovymame wrally -monitor generic_15

[barryabrams]

I was able to try World Rally tonight, but i wasn't able to get it in sync. I rolled the hsync and vsync knobs end to end, and I was able to get the picture to stop scrolling, but it was very, very distorted, like each row wasn't lining up. I could tell that it was the mame screen that comes up and asks you to hit OK because of the colors, but only because I knew what it was before.

I ran the command (with the flags) you suggested, with no change... still getting the same out of syncness. This is a pretty standard wells-gardner monitor. It came out of a dig dug and I tested my galaga with it, and it works fine. I mean, i'm getting advancemenu and the linux desktop to display fine. Is there a way to lock mame into that refresh rate?

I rebuilt my VGA cable, because i thought maybe i didn't solder something correctly, but there doesn't appear to be anything wrong with it.

Edit:
The VGA cable is connected directly to the monitor from the on-board VGA port. I do not have a special video card or anything. The spec sheet says it's an integrated NVIDIA GeForce 8100.

[Calamity]

The spec sheet says it's an integrated NVIDIA GeForce 8100.

You should have started with this! I was assuming you had an ATI card.

Well, the issue is probably related to non supported low dotclocks. Fortunately there may be a workaround to this, as we know that higher dotclocks do work (640x480).

So, open your mame.ini file (it's in the default folder, you'll find it easily, or you can also open it from gasetup, system setup menu). Then edit this value:

dotclock_min 8.0

Then raise this value until you get it working for all games. Start by 8.0 MHz, maybe it is enough with that, 12.0 will work for sure but keep it as low as your card supports.

[barryabrams]

dotclock_min 8.0

This totally worked! I was able to play world rally, and any of the other games. With a little tweaking from the monitor's horizontal position, I was able to get a picture perfect image. And the games are all running at 100%.

Thanks for all your help.

[Calamity]

Great news. I'll add the 'NVIDIA GeForce 8100' to your first post topic so it can help other users to find the relevant information.