Hi Everyone!
I own and operate Blizzard Mountain Pinball in Conifer, CO. We currently have 37 pinball machines and a couple of video games. My goal is to keep the games playing as good as possible, sometimes easier said than done! The games tend to get light to moderate use (it's not a barcade so they don't get beat to death).
I wanted to start a log this week since I had a couple of interesting repairs that illustrate a philosophy that I usually live by when repairing machines. I say 'usually' since this time both repairs almost had me chasing down a rabbit hole...
Machine 1: #indiana-jones
- Noticed last week that none of the lamps in column 8 were working. Wiring was fine (was able to temporarily jumper column 8 to column 1 and the lamps lit up). I suspected the TIP107 on the board, but I didn't have a replacement handy. Most of these lamps are on the Path of Adventure, so I left the machine operating, no further issues that day.
- Next day, the ball got stuck in the Mode Start hole. The kickout is not working. Switch worked fine, kickout did not work in test mode. Looked at the wiring, nothing obviously broken. Kickout started working. Figured it was probably a broken coil wire but decided to leave it alone since it was working again (I'm never satisfied with things that 'fix' themselves!).
- A few hours later, ball stuck again in the Mode Start hole. Turned game off.
- Next day, dove into the Mode Start issue, convinced that the little coil wire had broken on the coil. However, I took a small screwdriver to carefully pry on the wires and neither had popped loose. I tested voltage and both lugs had 75 volts. There was continuity (I forget the exact ohm reading) between the lugs of the coil. Didn't seem like a broken wire. I was able to put a jumper between the connector (pin 9) and pin 1 on the header on the power board, and the coil fired when I tested coil 1. So, again, the wiring was confirmed on the playfield. Seemed like another board issue.
- While testing the coils, I noticed another coil not working - the coil that knocks down the drop target blocking the captive ball (super jackpot shot) was dead too. Repeated the same jumper test (again, it was pin 9) and the coil worked.
- Now, the more astute among you might have noticed a pattern. Lamps in column 8 not working. Mode Start kickout is coil number 8. Drop target down coil is coil number 16. Hmmm.... Seems like a data addressing problem, and not an issue with the coils or transistors...
- I flipped the ribbon cable between the CPU and Power Driver board around. Everything magically started working!
A bad ribbon cable nearly caused me to dive into the power driver board and replace a couple of transistors to 'fix' the problem. And, it likely would've appeared fixed too, since I would've needed to unplug the ribbon cable to remove the power driver board. Who knows how long it would've worked before failing again!
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Machine 2: #medieval-madness (original Williams)
- The castle drawbridge (moat switch) wouldn't register hits, rendering the drawbridge (and thus, the castle) inoperable. Not much fun in this state!
- The moat switch is an opto. I cleaned the optos, no change. I checked the wiring, no breaks. I figured the opto emitter had died, but I didn't have a replacement. Left the machine off for the time being.
- Next day, the local Colorado Pinball Club had a meeting at my facility. A couple of us broke away from the group and decided to take a deeper dive into the Medieval Madness opto issue. Since we were testing with the coin door open, we didn't notice until later that upon powerup, (game not started) it would start kicking balls out of the trough. Hmm...that's not normal...
- We found the Trough Jam opto wasn't working. It was on the same row as the moat switch. Hmm...
- We also found the left ramp enter switch wasn't working. Again, on the same row as the moat switch. I noticed the diode on this switch was bent funny, it was shorting the column and row together at this switch. Bent the opto back up out of the way, and suddenly everything started working!
So I nearly went to the trouble of replacing the opto when the one in the game was fine. Simple fix for what seemed like a complicated problem!
Lesson: Don't assume it's the worst, always look for simple explanations first! Look for patterns, and look for other failures that might be related.
I don't know if this log will be helpful to people, or how regularly I'll be able to post. Please let me know if you found this interesting and/or helpful. I don't claim to be an expert, though I do have a fair bit of experience working on these games as a hobby for the past 15-20 years, and running Blizzard for the past 11 months.
Kevin
Westwood, NJ
