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Pacman/Galaga 20th & 60-in-1 Multigame Bartop Build

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CraftyMech:
I've been lurking on the forums for a few months and finally decided to take the plunge and get started on the project I've been planning. 

I started out wanting to build a Ms.Pacman/Galaga 20th Anniversary cocktail cabinet. I picked up a used board off eBay, along with a Jamma harness. However, when I sat down and really looked at the project dimensions, I started leaning towards a bartop instead. Looking through the amazing bartop builds in the forums, I was definitely sold on the idea!

Being on a budget I wasn't sure what to do when it came to the monitor. Back in the late 90's I was really keen to build a MAME cabinet, and I had 3 used 14"-17" CRTs just sitting in my closet. That project never got off the ground, and now in 2012 those CRTs are long since gone. In fact, I realized I had not a single spare LCD monitor in my possession either.

A couple weeks ago though I was digging through a box in the basement and realized I still had a Compaq Presario 433 "All-In-One" PC (circa 1994). These PCs were similar to the iMacs of the late 90s, with the computer & monitor integrated into a single case. After hunting down a spare AC cord (I used to have a million of those as well), I powered it up and the monitor still had a nice picture. Eureka, I had found my monitor!

The All-In-One design of the Presario 433sx (feel the speed!) featured a bottom chasis that held the motherboard and peripherals. An edge connector allowed this whole assembly to be removed, and this made it easy for me to find the VGA/power supply wires as they were all soldered into that connector. I found the +12v & +5v rails and made a 4 pin molex connector, and then soldered the VGA connections up to a male VGA connector. Next step, get a CGA->VGA converter hooked up to the Namco pcb, and wire up the Jamma harness.

CraftyMech:
It lives!

I used a GBS-8220 CGA->VGA converter to adapt the 5 pin CGA from the Namco pcb to my 14" VGA monitor. The initial setup was a little frustrating at first as the menus were in Chinese by default. Once I found the setting to switch to English though I was happy to find a full set of controls for H/V size/position, saturation, brightness, contrast etc.

The picture looked nice once I scaled and positioned it correctly, although I did have to fiddle with the trimpots for R/G/B on the converter board to get the right color palette. Overall though I'm really pleased with the board for the $. I have no idea how well it works with old school Jamma boards, but at least with the more modern Ms.Pacman/Galaga pcb it works like a charm.

Versus a LCD, I realize the bartop dimensions will be deeper than the slim builds I have seen in this forum. However, I don't think I'm ready to transition to LCD yet for classic gaming. The combo of monitor/power supply also is appealing, and saves me a little cash.

Next up I need to get some controls wired up, a little slow to navigate the service settings by just touching interconnects together :)

CraftyMech:
Back when I was a regular MAME user, I always liked to play the classics with the 'scanlines" option enabled. I've read about a couple boards for sale that generate scanlines for a VGA signal, and I was curious what kind of undertaking it would be to build my own design. It turned out to be fairly straight forward and I had fun playing with the VGA signals. I put up a number of interesting acid trips on the screen while working out the details :)

Once I had the scanline generator running, I wondered why my scanlines were vertical... then I remembered I'd turned my monitor on it's side!

The one downside to scanlines is the perceived dimming of the picture. Just turning up the monitor brightness doesn't really address the problem as the black of the background gets brighter as well. I'm going to look at boosting the RGB signals a little to compensate, which actually made me think about including trimpots for RGB intensity. The monitor I'm using has all its fine controls (RGB saturation, Hsize, Vsize, etc..) inside the case as trimpots on the pcb, where it is really convenient to reach right on in there with a screwdriver when the power is on and tune the picture ;)

emphatic:
What about the RGB pots on the CGA->VGA?

CraftyMech:

--- Quote ---What about the RGB pots on the CGA->VGA?
--- End quote ---

Good point!

I forgot to mention that the screenshot is from a 60-in-1 board (newly acquired). For my Ms. Pac-man/Galaga board, the CGA->VGA converter has a nice set of adjustments in the menus, and the RGB trimpots like you mentioned. I'm now thinking about perhaps using both boards in my bartop, with a switch to select between them (the 60-in-1 of course has Pacman/Galaga, but as a purist when it comes to my favorite classics I want to play the real deal!)

Unfortunately, the RGB/screen size adjustments that I made on the CGA->VGA converter to make the Ms.Pacman/Galaga look nice, don't work well for the CGA signal from the 60-in-1. So to use both boards in the bartop I'll need to figure out something for the 60-in-1 as far as adjustments go, using the boards VGA output instead of the CGA signal. One option would be to adjust the monitor internally (using the pcb trimpots) until the 60-in-1 looks good, and then adjust the CGA->VGA converter settings for Ms.Pacman/Galaga based on the 60-in-1 baseline. That combo might actually work pretty well, I'll have to give that a try today.

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