Reset issues on pinball machines

Often people will contact me about reset issues with Williams pinball machines, primarily associated with the WPC era from the early 1990’s. I presume they do a little searching around the internet and come to the conclusion this is a real common problem, solved by replacing BR2 (bridge rectifier) and C5 (filter capacitor).

What happens is that many people will attempt to shotgun these parts (shotgun means to replace without knowing if they are in fact defective).  Some of these people will have limited de-soldering experience, and end up damaging their Power/Driver board.

In my professional experience (30+ years), my opinion is that there is no common Williams reset problem.  Reset issues can occur in all solid state pinball machines (even on some EMs) and all brands, and it can be caused by many different things, most of them related to the power chain. When the voltage drops below a threshold, the circuitry is designed to reset the pinball machine.

I’m all for people repairing their own machines, and I’m happy to help and teach them.  But shotgunning parts on a printed circuit board is usually not good for the board.  The heat and physical stress from de-soldering a part will usually lift the copper pads or traces from the fiberglass, or pull out the metal plating that is inside the hole that the component pin is going through.

If you have a reset problem, get the correct diagnosis before swapping out parts.

With my oscilloscope, I can check BR2/C5 in about 60 seconds.  It’s immediately apparent when the bridge rectifier is defective; the pulsating DC will only have every other pulse showing.

Here are some reset issues I’ve worked on, and what the problem ended up being:

  • Independence Day (Sega):  This is one of the very few that ended up being the bridge rectifier.  In the case of Sega, it’s called BRDG21.

 

  • White Water (Williams): The owner was having a reset issue and had read about BR2 being the culprit.  He wanted me to verify that BR2 was defective. It turned out that it had already been replaced, along with C5. While I was at his home, the basement lights dimmed when the furnace blower switched on.  I suspected an issue with the house wiring (it was an old house).  He turned on other appliances and the line voltage reading dipped down to about 105 volts.  I suggested he try a uninterruptable power supply (UPS), normally used for computers, to handle these brownouts.

 

  • Black Knight (Williams): The basement of this home was wired with ground fault interrupters (GFI) after a flood.  Most pinball machines won’t work with a GFI.

 

  • Star Trek: The Next Generation (Williams): Reset issues on this machine were only in the first few minutes of power being turned on.  I replaced the inrush current limiter (varistor in the power switch box).

 

  • Starship Troopers (Sega): Resets were pretty random, but grouped together.  I traced the problem back to the F23 fuse.  It was loose in the fuse clips and running very hot.  I tightened the fuse clips and reinstalled the fuse.

 

  • Twilight Zone (Bally/Williams): The reset problem was caused by bad solder connections on the 5 volt regulator. The 5 volt regulators run very hot on Twilight Zone machines and the solder tends to get fatigued due the high temperatures. The old solder was removed from the pins and new solder was applied. The ground on the 5 volt regulator is connected to the circuit board with some screws. These screws were showing signs of rust and were replaced as well.

 

  • Twilight Zone (Bally/Williams): The reset problem was caused by the power connector, where the 5 VDC leaves the Power/Driver board at J114.  The insulation displacement connectors (IDC) have metal forks which pierce the insulation of the wire to make a connection with the copper inside.  These connectors are problematic due to the wire working loose due to vibration and movement.  I re-seated the wires into the connector and the problem was solved.

 

  • Doctor Who (Bally/Midway): same problem as Twilight Zone above, except at connector J101, where the low voltage AC power enters the power driver board before going to BR2.

 

This is just a sampling, but failures of BR2 are not as common as some people think. Also, I have yet to see a case where C5 was weak or needed to be replaced.

Golden Eye, Sega/Stern Pinball Machine (1994)

Location: Centennial, CO
Symptoms: Auto-launch ball shooter would not launch ball.  Lower playfield lights not working.

I opened the coin door on the pinball machine and immediately saw a coil dangling from the playfield.  It was the shooter coil and it was resting on the metal junction box.  It probably grounded out against the box causing the 50V supply fuse to blow.

The coil bracket had broken from the stresses and vibration of years of use.

The lower playfield general illumination lights were not working. I suspected a connection problem on the IO Power/Driver board.  I couldn’t find any problems with the connector. The lights started working momentarily on their own.  I could hear a faint buzzing that seemed to be emanating from the fuse.  I tapped the fuse and the buzzing would change. I removed the fuse and tested it.  It wasn’t blown, but there was a connection problem inside of it (more on fuses here).  I replaced it and the lights began working reliably.

Once the lights and the shooter coil were fixed, I played a test game and discovered a playfield ramp switch that was dangling with nothing holding it. I wasn’t able to locate any screws lying in the cabinet.  So I reattached it with a new screw.

Sega South Park Pinball Machine

Symptom: It would shoot two balls into the shooter lane.

At first look, the playfield switch in front of the plunger was badly bent and not reliably sensing a ball.  I assumed this is why it was loading the shooter lane with two balls.  As I tried to straighten out the switch wire, it broke.  I repaired the switch with some piano wire (I guess it’s steel wire) that I obtained from McGuckin’s Hardware store, and epoxied the wire on to the switch lever.

As I investigated further, I discovered the reason the switch wire was bent was because the one-half of the fork was broken off the auto launch kicker (500-6091-00).  When ever the auto launch mechanism shot the ball, it would jam the ball sideways.

Broken Auto-Launch Kicker

Broken Auto-Launch Kicker

 

I found the broken piece down in the bottom of the cabinet. The owner took it to a nearby muffler shop and they welded it back together.  With the switch replaced, and the arm welded back on, I fired up the machine to find it still deposited two balls into the shooter lane.  The playfield switch was functioning correctly.  After another 15 minutes, I realized there were 6 balls loaded into the machine, when there should only be 5 balls.  It never is what you think.   The other stuff needed repairing even though it wasn’t the original problem.

Replaced many bulbs.

Location: Superior, Colorado