Fixing slingshots and coils that don’t fire on Williams System 3+

In this video series, I go over a 1979 Williams Flash pinball machine that has a few issues. After rebuilding the sound card and getting the sound working, I move on to figuring out why several of the playfield features are not working. I go through step-by-step trying to figure out where the problem is and why certain coils are not firing, eventually tracing it all back to logic chips on the driver board. Watch me as I fumble my way into getting the game back to 100%, and as usual, pardon my occasional tangents and erroneous conclusions as I diagnose where the problems are in this un-edited video series.

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In Summary, there are a few steps to follow when you’re trying to diagnose a playfield coil that does not properly fire.

First, as always, make a visual check of the playfield and connectors to see if you notice any obvious problem like a broken wire or diode, coil winding that has come loose, or an obviously burned coil, or cracked/loose solder joint.

Second, check to see if there’s power to the coil and it can be manually trigger by grounding the non-power-supplied lug.

Third, go into coil test mode and see if the coil can be fired from the diagnostics. (if it can but not in game play, it is likely a switch problem)

Forth, trace continuity in the switch matrix wiring to/from the playfield. Also note (as I later discovered while working on this game) that if the coil is using one of the special solenoids, it will have a second trigger switch/line that needs to be checked.

Fifth, if continuity checks out, then test the switch matrix or trigger lines on the driver board.

If you’re at this point and things still don’t work, it’s time to examine the driver transistors and pre-drivers… you should have, at step 1, examined the driver board to see if there were any obviously burned components on the driver board. Now you have to bust out a multi-meter and check the transistors and ICs in the signal path — noting that if they test good, this dosn’t mean they necessarily are good.

If there still is no conclusive cause, you have to start replacing components, starting with driver and pre-driver transistors, and then the 7408 and 7402s.

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Fixing Bally -35 reset issues and bullet-proofing the power driver board

I was having an issue with a Bally “Supersonic” pinball machine randomly resetting/rebooting. The problem was traced to irregular power coming off the driver board. In this video series I go over a necessary process to bring these old boards back “up to spec” as well as a few improvements that make the game overall more reliable.

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First Look: 1978 Bally Supersonic – damage done by batteries takes its toll

Today’s I’m looking at a 1978 Bally “Supersonic” pinball machine. A friend had this in storage for a long time. While the game was in pretty good shape for its age, the original MPU board still had the battery on it, and the electrolyte from it leaked all over and damaged many components. Here’s a first look at the game.

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Fixing stuck drop targets on a Bally SS pinball machine (Mystic)

This is another one of those video series where I thought to myself, “If I were smart I would edit this.” But then I thought, I can’t be the ultimate pinball repair guru and I’m not really trying. If I have some kind of “angle” it’s that I’m doing a FPS (First-Person-Shooter) perspective to the hobby, collecting and restoring. And often times when you’re in an FPS, you poke your head down the wrong hall and get fragged. This is kind of how this video series starts off but it takes part 3 to realize the plot twist…

Ok I’ll get off confusing metaphors and back to pinball repair..

The problem I had was when I got this Bally Mystic, one of the targets was broken. I had ordered replacement targets. I opted for the same style as the side targets even though on many Bally Mystics, for some reason, the front targets are bullseyes and the side targets have explosion graphics on them. Go figure? Anyway, after replacing the targets I discovered that two of them would often get stuck in the “up” position and would often not retract when hit. I knew the springs on some of the targets were old and had “lost their zest” (that’s an official technical term by the way). So I thought I’d make a video on replacing the springs, showing an alternate source for some of the components as well as a trick to make an old spring kinda new. Along the way I discovered the real reason why the drop targets weren’t resetting…

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