Page:Gametronics Proceedings.djvu/80

 #Erratic operation at low line conditions.
 * 1) Catastrophic failure at high line operation.
 * 2) Game board or audio board signals causing spurious video signals on display.
 * 3) Static discharge failures (or free game operation).
 * 4) Power supply failure due to overload.
 * 5) Shock and vibration failures.

1.)Infant Mortality Component Failures

Most game manufacturers have found that a 48-hour burn in of the completed system will practically eliminate these failures, while buying from reputable manufacturers (including the power supply) will greatly reduce the number of failures (and the high rework costs) during burn in.

2.)Heat Induced Failures

While most computers use metal cases for good heat transfer and adequate venting for good convection cooling, most coin operated video games operate in a totally enclosed wood or fiberboard cabinet with no venting. This is done to prevent spillage into the games or probing with wires, etc. to attempt to get free games. As a result, the heat environment of the game is considerably worse than that of most computers with heat rises of 20 to 40°C. not uncommon. Heat induced failures generally occur as a function of both time and temperature and will usually occur after weeks or even months of operation. This is the major cause of power supply failure in the games.

Most O.E.M. power supplies use a minimum amount of heat sinking depending on the excellent thermal conduction and good convection cooling of most electronic equipment for their cooling. A 5 volt 6 amp supply that will operate at full power for years in a well cooled computer, will frequently fail at 5 amps operation after a few weeks in a video game. The failure most frequently is rectifier failure in the many O.E.M. supplies that use parallel 3 amp diodes for rectification, and pass transistor or filter capacitor in the better designed units. To overcome this problem, Adtech Power uses 50% more heat sink, a pass transistor with twice the power rating, rectifiers with up to 5 times higher rating, and a larger 10-year life filter capacitor. Another solution is to use a power supply with at least 50% higher rating than that required, i.e. a 5 volt 9 amp power supply for the 6 amp application.

Fortunately, most coin operated game cabinets have a surplus of room and some judicious layouts can prevent many heat problems. The game board should be mounted vertically close to one side of the cabinet and as low as possible to allow the heat rise away from the board. As much copper as possible should be left on the board to act as a heat spreader. The power supply