[rescue] any video game rescuers?

[Mr Ian Primus]

--- On Thu, 4/21/11, Ethan O'Toole <ethan at 757tech.net> wrote:

> Pretty cool. In the arcade world they are called PCB's. The
> later ones adhere to a standard called JAMMA where the card
> edge connectors are somewhat standard. This allows them to
> be swapped out. Of course different "cabs" (cabinets) have
> different control panel layouts.

Different control panel layouts, different wiring, different power supplies... JAMMA made things easy, but that was well past the "golden age" of arcade games. All the classics use their own pinout. Some don't even use standard +5/+12 DC power. For example, Pac-Man has the power rectifier, filter and regulator right on it's one PCB. The edge connector carries +8 and +13AC, directly from a transformer. Of course, this connection is a weak point in this game, as it invariably burns right at the edge connector. They used tin plated circuit board connectors and really cheap wiring harness connectors.

That's one big place where fixing arcade games gets fun - is dealing with repairing things that were intentionally cheap and low quality. Many things are poor designs.
 
> Also, the monitors in the cabs come in horizontal and
> vertical. Galaga and Ms Pac Man are vertical, for instance.
> The screen is sideways.

Yup! And note that there is no electrical difference between a horizontal and vertical monitor. They still scan the same way as a conventional television. The only difference is the mounting brackets, or simply the orientation in the cabinet.

> The earlier games were low res or standard. 15khz. Then
> came medium res which is like 25khz, then VGA which are
> 31khz.
> 
> The classics were low res. RGB and sync output.

There were some borderline classics that were medium res, like Paperboy.

Fixing those old medium resolution monitors is not fun. Another example of "cheap and nasty", some early medium res monitors are factory modified standard resolution chassis. They changed the scanning rate and made some other mods - but without beefing up the active components to handle the load. The side effect is that they get HOT, and get nicely browned and cooked over time...

But still, all that aside, collecting games is a lot of fun. I've got about a dozen of 'em in the basement, and do repairs for several frinds in the area. As an electronic geek, it's a lot of fun fixing these games, since you repair things down to the component level. Fortunately, most schematics are available. Although sometimes the schematics don't match the hardware, found that out when I was fixing my Robotron...

-Ian