Bally Star Trek Ground, Solenoids, and Sound

Even when you get a machine ​that's as nice as the Bally Star Trek I picked up, you're still bound to have a few issues. It's just the nature of owning old electronic things. In this case, one of the issues I experienced was my fault, one might have been my fault, and the other wasn't anybody's fault--and it was an easy fix.

The Ground Issue

Older games like Star Trek don't have hinged back boxes. That means that, to transport them, you unbolt the head and lay it flat on the top of the machine (cushioned by padding or cardboard) and wrap stretch wrap around the head and body of the machine to keep the head from sliding. You could unplug all of the wires and remove the head entirely, but most people don't do that. it's a pain in the butt.

As we were removing the head to move the machine, the former owner pointed out that the grounding strap that runs from the head into the body of the machine was super tight--hardly any play in it at all. I probably should have at least detached that...but I figured I'd just be careful. Of course, when I was putting it back together, the grounding strap snapped. 

I didn't have any grounding strap laying around, but I figured that wire's wire. So I used a lamp cord and ran that from the grounding point in the head to the broken part of the strap in the body and spliced the two together. Pretty much immediately, I noticed that the game was resetting on its own at random intervals--a sure sign that there's a ground problem. So, I did the right thing--I ordered 25 feet of grounding strap from Amazon and fixed it properly.

One other interesting note (which might have led to the solenoid problem below) is that, when I was trying to find out where the broken grounding strap was attached, I inadvertently discharged a capacitor in the body of the machine. There's a small box on the left-hand side. I don't know what it does (the manual doesn't mention it), but it has a capacitor on it, and the grounding strap runs behind it. As I was pulling on the broken strap, I shorted the capacitor (BIG shower of sparks). Scary, but no harm done. Maybe. (Read on.)

The Solenoid Issue

After the ground issue was fixed, I figured my problems were all behind me. I played a few games and everything was fine...but, then, the pop bumpers stopped popping. And the slingshots stopped slinging. I'd shut the game down and restart, but the same thing happened after a game or two.​

I opened up the back box and noticed that the solenoid board (upper right) was VERY warm. Not surprising--it does have high voltage that runs through it, and (as a result) has a HUGE heat sink on it. But, still...it seemed abnormal.

A more repair-savvy collector would probably start troubleshooting the board. I decided to order a new one. It's my way.

Alltek Systems makes brand new boards for older Bally and Stern games. This game already had an Ultimate MPU Board (which, among other things,

lets you set Bally games to free play--an option not available on most of the games on the factory MPU board). They also make the Ultimate Lamp Driver (which I added to my Centaur when I upgraded it to LEDs) and an Ultimate Solenoid Driver. The primary advantage of ALL of these boards is that they're modern technology. More reliable, more energy efficient, and cooler-running than the boards they're made to replace. 

At any rate, replacing the old solenoid driver board with the new one was a simple board swap that took about five minutes. The game works great now. No issues.

Did I cause the problem with my little capacitor discharge incident? I don't know. But I'm glad the problem did happen considering the hack I found on the original solenoid driver board. Check out the picture above and note how someone apparently decided the best way to replace the fuse was to solder two bits of wire to the fuse holder and then solder the fuse to the wires. Even a non-repair-savvy guy like myself knows that's not the way you repair a board!

The Sound Issue

As soon as I bought the game and set it up at home, I noticed two things about the sound. First, there was a loud (and very annoying) buzz from the speaker when the game was in attract mode. it happened every time the score displays switched between showing the score of the last game and the high score to date. The other thing I noticed was that, occasionally, there were notes being dropped in some of the peppy little tunes the (primitive) sound system plays throughout the game--most notably, the janky version of the Star Trek theme that plays at the end of the game.

A little reading put me onto the simple solution for this one. It seems that, if you screw the sound board in tightly so that it makes contact with the metal frame in the back box (which would seem to be the right thing to do) you sometimes get this buzzing/sound-dropping behavior. To determine if this is the case, just loosen the screws and pull the board away from the metal frame.

I gave it a try...and both sound problems were solved! To keep the board from drifting back to the metal frame, I found some non-conductive cardboard washers that we (for some reason) had in our tool chest, and put one on each screw behind the board. No more buzzing...and I can now revel in the plinking melody of the Star Trek theme after the last ball drains.