The Pinball Fix


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"The Concorde made its first commercial flight on January 21, 1976."

Section 1. The Electronics Continued

Right Flipper Machine-Gunned

There are a couple of things that could cause this. Below is a quick list.

  1. EOS Switch not adjusted correctly.
  2. EOS Switch needs cleaning, filing.
  3. EOS Switch needs to be replaced.
  4. Wire on the flipper coil is loose or disconnected. Could be a wire attached to the lower power lug or the thin copper wire from the low power portion of the coil to the lug.
  5. Dirty flipper switch which needs filing.

Most of the time, maching-gunning is a broken wire on the low power coil. Flipper coils are actually two coils in one, a high-powered for the initial hit and then a low power to hold the flipper in place if you continue to hold the flipper button. When you push the cabinet flipper button the high power activates. When the plunger goes into the coil it then hits the End-Of-Stroke (EOS) switch which energizes the low power coil and shuts off the high power coil. This then holds the flipper in place. If the low power coil's wire is broken, then the lower power coil does not work and the flipper won't hold so the spring pushes the plunger back down. However, since you are still holding the button the high power comes back on as soon as the EOS returns to its position. This causes the flipper to kick again. The process repeats very quickly over and over causing the machine gunning.

On my game, the wiring was fine and the issue was with the EOS switch. I filed the cabinet flipper switches and the EOS switch. Note that these are really the only ones you should actually file. Most switches should not be filed as they are not as heavy duty as these switches. I adjusted the EOS switch and at times the flipper would work fine and then it would start machine gunning again. The switch was in pretty worn so I decided to replace it. This fixed the issue.

Two Wire-rollover Switches and Eight of the Star-rollover Switches Did Not Work

This was caused by a couple of issues. This game has 11 star-rollover buttons. Nine of them did not work at first. I replaced the old stars with new ones which doesn't really fix anything unless the plastic star itself had a broken base. Some of these didn't work due to a bad connector and/or pin on the MPU. Replacing them fixed these. The rest needed their switches adjusted. Star rollovers take a lot of patience to get them to work just right. It's easy to gap them too close so that they are always on or every vibration sets them off. It's also easy to gap them too far making them not work. Adding to this is that you have to adjust them with the playfield up and then you have to put it down and test it. The difference in the vertical versus horizontal position can affect whether these switches works or not. Once you gap a few correctly, it gets easier as you get a "feel" for how far apart they need to be gapped.

As for the wire switches, one was corrected when I re-did the connecotor/pins on the MPU board. However, the left outlane still did not work. I replaced the diode on it and it fixed it. What is interesting is that when it wasn't working it didn't seem to affect any of the other switches in its row or column in the matrix. So, I'm not 100% sure that the diode was actually the problem. It may have just needed to be soldered better and in doing the diode I corrected it.

One Display Did Not Work, One Was Missing a Digit, and Three Had Major Burn Marks in Them

On the display that was missing a digit, I replaced the transistors that affect this which was an easy fix. For the displays with burns in them, I replaced the worst of them with some spares I had. Two of them had minor burns so I put them in the #3 and #4 players. I would have replaced them but I didn't have any more spares laying around. I figured it isn't often that the #3 and #4 players are used. Plus, they still worked and weren't burnt too badly.

Alltek Replacement MPU

After having fixed all of the issues and getting the game running like it should, I knew that I was going to give it to my son's father-in-law who lived six hours from us. I didn't want this game to break down on him after we gave it to him, so I decided to go ahead and install an Alltek replacement MPU. Since the original MPU worked, I was able to sell it for a decent price along with a slightly damaged WPC board I had in my possession. The money I got for those boards helped offset the cost of the Alltek board.

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Below is the backglass. If you look close, you can see the delamination on the bottom right.

backglass front
The whole machine after delivery to my son's father-in-law and set up in his man-cave.
machine final