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Mapping pinball trends for the casual enthusiast…

TECH: WPC Resets, the bane of our existance!

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If you own a WPC game, its almost a given that you have experienced a reset problem at one time or another. My most recent experience with this annoyance was with my White Water. I had “5X the Fun” running and had just started multiball. Big points were coming my way. Sure enough, with coils firing and flippers flipping, the machine’s power supply collapsed under its own weight, and I experienced the dreaded reset. I hung my head and softly cursed, knowing I had a long journey of troubleshooting ahead of me.

To dumb it down a bit, a reset occurs when the +5 volt power supply, which runs the “brains” of the machine, diverts from an acceptable range of voltage. This normally happens when the flippers are fired, stressing the +5 volt line and causing a dip in voltage. To protect the brains of the pinball machine, a watchdog chip was inserted in line with the +5 volts. When this chip recognizes a flux in power that doesn’t agree with the +5 volts range it should normally be getting, the game automatically restarts, thus easing the load. The flipper stress on the +5 volts is caused by a weak link upstream in the chain…and its a very long chain with a lot of elements that could be out of order. In the end, the watchdog chip congratulates itself on a job well done…however, it turns into a vicious cycle of resets and much weeping and swearing will commence on the part of you the owner.

With my reset issue, I luckily had Clay’s WPC repair guide and PinWiki as references, not to mention helpful colleagues over on Pinball Revolution. I guess the first advisable thing to do is not panic. Do not immediately assume the worst. For those who like to jump to conclusions, there is a stigma that these resets are caused by components located at BR2/C5. To quote PinWiki on their introduction to fixing reset problems:

“A long time ago……in a pinball galaxy far, far away…a kindly fellow was playing a nice game of pinball, hitting all the shots, and earning multiball after multiball. Just as he was about to beat the game’s high score to date, the WPC game MPU reset. “Not-A-Finga” he yelled in some ancient, dead, language. A visitor, from the neighboring planetary system noted that, “I once fixed that by replacing BR2 and C5”. And lo…the mantra was born. Fortunately, through advances in both our knowledge of these game systems, and the application of clearer thinking, we’ve come to realize that leaping to the “solution” of replacing components before doing real testing is not advisable. Most pinball owners do not possess the skill, experience, and tools that would allow them to work on circuit boards without damaging an expensive, and sometimes irreplaceable board.”

After troubleshooting with PinWiki (highly recommended) and my multimeter, I was able to determine that it was a simple connector issue between the power driver board and the CPU.  A relief indeed! Reseating the connector fixed the problem temporarily, however the pins and connectors were swapped out to fix the solution long-term. If I had taken the board out and blindly replaced the BR2/C5 as the mantra above states, the issue probably would have been “fixed”, not because I swapped out the above components but because the connectors would have been reseated in the board removal process. The resets would have resurfaced and I’d be right back at square one.

Without a doubt, resets are an absolute pain in the ass. With so many novices joining the hobby, myself included to a certain extent, everyone is looking for a one-step, easy solution that requires less work than removing boards and intricate soldering. No easy solution does exist, resets occur for thousands of different reasons. However, a piece of technology is now on the market that appears to ease the burden on that overtaxed +5 volt power supply and has become the reset elixir for many hobbyists. This product is called the WPC MPU Power Fix Daughterboard and has sprung from the mind of Rob Kahr.  Its introduction has not come without criticism. I had the opprotunity to speak with Mr. Kahr about his new product, the “power” it harnesses, and what it can do for the community through an email interview and can be found in a post appearing later this evening.

Further Reading:
PinWiki – WPC Game Resets
WPC MPU Power Fix Board – kahr.us

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One thought on “TECH: WPC Resets, the bane of our existance!

  1. Pingback: TECH: WPC Resets and the WPC MPU Daughterboard | CREDIT DOT

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