Sounds like a typical WPC reset issue.

There are troubleshooting steps are here:

http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Game_resets

Or, as a stopgap measure or to assist with troubleshooting, you can use this bypass module:

http://www.kahr.us/daughterboard.html

Before you get too far, open the backbox and look for a "Z" connector, a lot of times these connectors are loose or just plain old and oxidized so they don't make good connections...try reseating it a few times and see if the problem goes away. If not, then start looking at the link forceflow has posted.

"Bad Connections in Inter-Harness Connector: "Wide-Body" Games Only: Demolition Man, Indiana Jones, Judge Dredd, Popeye, Road Show, Star Trek: TNG, Twilight Zone. In these games, the 12-volt/ground harness coming off J114 on the left side of power/driver board will have a 7-position gender-changer connector (female-to-female) in it, with 6 wires (3 black, 3 gray), a few inches off the board from J114. This is sometimes referred to as a "Z" connector. In many cases, especially as these games continue to get older, this connector has been known to be the cause of reset problems when it's connections are dirty, oxidized, or damaged from possible overheating or excessive current draw. Reseating this connector (or replacing it if it is damaged) may help cure a reset problem. Bypassing the connector altogether (cutting it out and hard-wiring the wires) is the best option to eliminate it as a cause of reset issues- at present and in the future. This connector was only used at the factory to ease assembly between 2 backbox harnesses, and isn't needed in normal use or maintenance of these games".

http://www.actionpinball.com/tech/reset.php

zee (resized).jpg

I had a similar problem and it ended up being a broken diode on the flipper coil.

I wonder how many people’s first post on pinside is “help! my game is resetting when I hit the flippers!”?

rkahr came to the PNW show and did a seminar on what his daughter board is and does. He explains it as not being a stop-gap measure but as a solution that treats the 5V circuit to the CPU as a stand-alone feed, similar to other circuits in the machine.

I use a kahr board on my TZ and it works fine.

For now. You'll love the day it still resets with that board in. I remember it very well when it happened on my TAF....

The rectifier bridge also can cause resets and or bad soldier joints there.