I’m finally getting around to fixing my Bally Theater of Magic pinball. In this case, as is typical, the trunk stopped working. The trunk is not working at all, so let’s find out what’s wrong and I’ll also go into replacing the trunk opto board with a new and improved, German-made board. Will this fix all the problems? Watch and see….
Part 2: Work continues on the Bally Theater of Magic pinball – in this case, we’ve figured out why the trucnk wasn’t working even after installing a brand new, improved, aftermarket trunk board. The motor driver controller was shot! Now, while we’re bulletproofing the game, this is a good time to install the special Cliffy Protectors around the trunk to make sure there’s no damage to the plafield. In this video I go over how to lift the trunk out to be able to do this, among other things.
We finally got everything working on the Theater of Magic pinball – here’s a summary of everything that’s been done, along with an odd problem I had with an aftermarket proximity sensor.
An odd assortment of things are wrong on this TSPP pinball machine. Are they related? Let’s look into what’s wrong and where we should look to fix things?
This has now turned into a multi-part series where I also discover some other issues:
So here’s the take-away from the first 5 parts of this series.
Everything was basically inter-related (except I believe the slingshot and pop bumper coils were separate failures). The trouble with the ball trough opto led to the failure of the shooter lane coil. When the ball trough opto started failing, it signaled false switch closings, tricking the game into thinking balls were moving through the trough and causing the VUK to try to clear a problem, which caused multiple balls to go into the shooter lane. This happened faster than the auto-plunger could handle and once X number of balls went in there, the plunger could not clear them, and eventually the MPU sent too many “fire-the-coil” signals and blew the driver transistor — interesting that it blew the driver transistor before it melted the coil — I suspect either (or both) can happen in this circumstance.
What’s interesting about this, is that this problem could be compensated for by software. It’s also possible the other coil failures are the result of a similar characteristic: Not having a certain timeout or duty-cycle enforced on coils. Meaning… the software could check to make sure that if a coil is firing too much (say x amount of times in y time), that it knows there’s some kind or problem and then put the game into some sort of error state rather than blow the coil or the drivers. I know in some later games this happens… when errors are encountered, the game just stops trying to fire coils rather than blow them.
This obviously isn’t the case in some of these 2000-era Stern games. I’ve noticed this on several titles including WPT and NBA as well.
Unfortunately, there’s not likely to be a software fix available, so what is important is to keep an eye on game behavior and try to catch switch malfunctions before they blow things. Had I been told about the shooter lane situation earlier, I could have fixed the opto before it blew the driver transistor on the SDB.
In this video designer Stephen Silver shows us the inner workings of the P3 system. It’s a very interesting and efficient design that makes the game surprisingly easy to service, with lots of features not found in typical pinball machines.
Many games, especially older games would have their playfield mechs screwed directly into the wood with wood screws. On areas like bumper posts, these can take quite a beating, get loose and become stripped. Here’s a simple technique to repair stripped holes to make the screws bite back into the playfield.
After having this game on location for awhile, I thought I might report on what types of wear and tear and damage I’m running into, and what was wrong with the game. I think we’ve found a few “weak links” relating to parts that probably should last a little longer. Check it out:
Now that I’ve got Haunted House running, it’s time to bulletproof the game – ideally you’d probably want to do the ground mods from the very beginning because in some cases, you might not be able to get the game working otherwise, but in this case, I managed to get the game to boot and appear to play well, so now we’re doing the required ground modifications to make the game more stable and reliable.
What’s actually involved in that?
It’s pretty simple. Gottlieb used single-sided edge connectors (unlike Trifucon which has contacts on multiple sides) for most of their connections. Over time, these connectors tended to fail, either by the contact surface becoming oxidized, or the blades becoming fatigued and not making good contact. Since ground is so important, without a solid contact, the game can behave in a variety of different and unpredictable ways, from random reboots, to intermittent issues with everything from lights to sound to coil firing. The general rule with Gottlieb games is if you’re having a weird problem that isn’t consistently repeatable, there’s a good chance it’s related to the powertrain. The most obvious culprit in the power chain is going to be the ground/return lines.
In-a-nutshell, the ground mods involve running an extra ground wire to tie all the different board’s ground lines to a common ground, and tie the head and the cabinet ground lines together — the only exception is you keep the 45v solenoid ground line separate (this is to ensure that if there’s a coil short, it doesn’t send high voltage to the rest of the game’s more sensitive components). Each board has a different recommended spot where you should tap into the ground, often it’s near one leg of a capacitor (which should also be changed if they’re original). Use 18 gauge wire (preferably green colored) and tap into each board with one end in the designated spot, then crimp a spade terminal on the other end and tie all the boards to a single ground plane (usually the metal bracket that mounts the power supply in the upper left corner — be sure to sand the paint off the area so you can make contact (alternatively you can also solder directly to the bracket.
Once you have all the boards tied to a single plane, you want to tie that to the head and the cabinet, by running wires from the power supply bracket to the metal frame in the head, and then one down into the cabinet to the transformer board, where you’ll find a ground backplane you solder to (on System 80B games, you’ll also want to take all the ground wires that terminate on the transformer board and tie them together, preferably eliminating the molex connectors they used which cause problems).
Click at the top of each image below for larger versions: