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

[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]

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

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.

[CraftyMech]

I need to sit down and start working on the cabinet plans, but in the mean time I did some more work on my scanline generator.

I remember back in the '80s I used to stare at the soft glow of the arcade monitors and wonder why I couldn't get the graphics on my Commodore 64 at home to look like that on my tv. A scanline generator (or the "scanlines" option in MAME), brings back some of that old arcade monitor feel, but those soft glowing edges are missing.

So I modified my scanline generator to also manipulate the RGB signal to introduce what I'm going to call "bleed". The bleed kicks in for the most part where edge transitions are harsh, like white text on black, the edges of the walls in a PacMan maze, etc. Injecting bleed on all three signal lines sort of cancelled itself out, so I'm currently testing bleed on just red & blue.

The photos below show the effect, with the right image of the "High Score" label in Ms. Pacman captured while running bleed on the blue/red signals, and the left image as just plain scanlines with no signal manipulation.  The photos are straight from my camera, with just cropping and resizing and no other manipulation.

I'm still playing with the component values, but I like the effect, it worked better then I expected and brightens up the image a bit  and adds some of that glow I always loved as a kid.

[Malenko]

I have no idea how they did it, but if you have a 360 check out Final Fight on xbox live arcade, they have some CRT monitor effects (like Phosphor glow) that are just flat out awesome.

[CraftyMech]

I'll have to check Final Fight out.. I like the xbla classics, for the most part the developers have done a good job with the emulation.

The phosphor bleed effect I built is a tweak to the analog circuit, but it sounds like the developers of the xbla Final Fight game used a custom graphics engine that simulates the appearance of the old arcade monitors. I hope that trend catches on, the other xbla classics I have played rendered the screen in the right proportion (letterboxed) but didn't offer even a software scanlines option.

[CraftyMech]

Time to get the show on the road and de-case the display to see what kind of footprint the 14" CRT monitor will have.

The monitor is shown in the normal horizontal position in the photo, supported by the remains of the pc motherboard case. I'll be turning the monitor on its side for a vertical orientation, so the first problem I had to solve was how to reinforce the structure once that bottom section of U shaped metal sheeting was removed. Naturally that plate was what held the three separate pcbs of the monitor/power supply assembly together, so I had to put my thinking cap on for a bit.

[CraftyMech]

Working late into the early morning hours, I came up with a sub-frame for the monitor built from aluminum angle & box channel. An early challenge was how to position the monitor vertically, and at the same time allow it to tilt back at an angle. In the horizontal position, the monitor already had a slight angle of layback, so I would need to counteract that angle as well so that when viewed vertically there was not a side-to-side lean.

I came up with a sturdy frame that included posts in front of the right height to cause the tube casing to angle back about 10 degrees. On the back end I put a swing arm (anchored by a 1/4" bolt) that allowed me to skew the whole assembly a few degrees from square, which eliminated the layback that was present in the horizontal configuration. So by the end of it all I had a nicely orientated vertical monitor, mounted on a solid rebuilt chasis. There was much cutting, grinding, some bleeding, and a little cursing.

[CraftyMech]

Had a minor setback this morning... given the age of the equipment I am working with I was half expecting something to stop working. The monitor powers up and still works great, but now the 12v and 5v rails are dead. A little refresher from earlier in the thread, the monitor I am using is from an old Compaq all in one PC. So there is an extra pcb attached to the monitor that provided power via the old AT spec to the now removed PC motherboard.

I repaired a power supply once about a decade ago, but honestly they make me nervous. I'm encouraged that the monitor still works, so that seems to imply that the high voltage portion of the supply is working correctly and I don't need to get close to that stage. On the other side of the board is an AT connector, and right next door are 2 voltage regulators for the 12v & 5v rails. Measuring with a multimeter the traces leading into those regulators have no power at all.

I am a bit bummed, but the project goes on! If I can't get the supply working again I'll just opt for an arcade power supply since they are slim and compact. Just a shame to have that third monitor pcb taking up space and not providing any functionality.

[CraftyMech]

One thing I've noticed about just simple hardware scanlines is that on low-res games (Pacman, Galaga, etc..) they do the job, but removing half the pixels from a low-res display doesn't do any favors to text, and small bitmaps.

So I modified my scanline generator to handle variable intensisty scanlines via a trim pot for each R,G,B signal. The intesity of the scanline can now be adjusted from near black, all the way up to the point were the scanlines basically vanish. I personally found a setting of 1/3 intensity to work the best. At that intensity, the scanline rows are filled in enough that you don't get the impression half the display is missing like you do with a black (blanked out) scanline.

 I've been thinking about scanline orientation, and switching to the 1.8v version of the microcontroller I'm using so that I can use the vsync line as the power supply.

[CraftyMech]

I should really google topics more before I just dive in... just found a long thread from a different forum about a scan line generator called the T-SLG. Basically does exactly what my design does, so reading up on it would have saved me several days of fiddling. I may stick with my micro controller setup, or switch it out for the two ICs the T-SLG uses. Either way I need to get back to the task at hand, finishing up the cabinet plans and start cranking out some sawdust!

[CraftyMech]

Here is a photo of my scanline generator, which I am dubbing the "mini SLG". I think the footprint could still be about 1/3 smaller. I won't have a lot of room in my bartop design since I am using a CRT monitor, so every little bit of space saving helps. I'm going to go with this prototype and see how it works out, my only concern is cabling since VGA cables are heavy, shielded cables and not very flexible.

[CraftyMech]

Accidentally posted this update to my bartop thread instead of my "side-projects" thread. In any event, the photo below is my latest build of my scan line generator that I'm going to use in the bartop. The design shrank down nicely!