MCR games use a reset circuit that commonly goes bad. The battery on the power supply leaks and eats through it. If your supply is toast, it's possible to run the MCR games, (Tapper, Satan's Hollow, Tron, etc., etc) from a switching power supply. The reset circuit is required to boot the game at power on. If it is not functioning, you'll usually be greeted with a static screen full of random blocks of garbage. This circuit is actually designed to reset the game in case the power drops below a certain voltage. It also resets and starts the game at power on when the power supply reaches +5.

It's recently been reported that you can get a lot of the MCR games to boot without a reset circuit if the battery circuit on the power supply is working and you simply disconnect the reset line wire (the purple one). If your battery is dead, missing or just not working, you can run +5 to the v.batt pin as a temporary fix untill you install a new battery (run it to the v.batt pin on the main PCB, not the power supply). Since the OEM batteries will leak and eat your power supply, if the original is still there, remove it and replace it with something mounted off to the side that won't hurt anything if it leaks (see bottom of page).

If that trick still doesn't work, you can build one of these that should work for most games.

To create a fake reset circuit, build the following circuit:

Here's the pinouts of the original power connectors:


1 - V.BATT
2 - n/c
3 - +5v
4 - A.GND
5 - +5v
6 - +5v
7 - GND
8 - GND
9 - GND
10 - GND
11 - +12v
12 - +12v
13 - n/c
14 - n/c
15 - RESET

J5 - 15 Pin

1 - +5v
2 - +5v
3 - GND
4 - +5v
5 - GND
6 - n/c
7 - GND
8 - GND
9 - +12v
10 - GND
11 - GND
12 - n/c
13 - +12v
14 - +12v
15 - GND

Be sure to use a high quality switching power supply. Some people have reported an annoying audio hum after installing a switching power supply of lower quality. I personally experienced this one time with a Wacko and putting a large cap across the +12 and ground on the supply eliminated the hum. Your milage may vary.

You can connect 3 "AA" batteries to the "v.batt" line if you want to save high scores and operator settings. Just put a 1n4148 diode on the line so it doesn't try to charge the "AA"'s. That's a no-no. Be sure to get the polarity right and be sure to connect the AA's to the same ground as the power supply.

I also urge you to try to keep the original harness intact in case you ever want to go back to the original supply or you want to sell the game to someone who does. The molex connectors used for the power harness are common and the crimp tool to build an adapter that will plug into the original harness is fairly cheap too.

Questions and comments can be directed to me at:

[email protected]