WOZ Throne Room Bug Exposed

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It was recently revealed in some online forums that a bug was discovered in the Wizard of Oz program code, that allowed very lucrative shots to be done repetitively, racking up large amounts of points.  This exploit was observed being used by a high-level pinball player and attracted the ire of WOZ software developer Keith Johnson, who was quite upset he had to find out about the bug from others after it was used in a competitive environment.

Keith was understandably upset, and I don’t blame him.  But once there was a bug known, those that were aware decided to keep it secret until it was patched.   Unfortunately with some people knowing the bug and actively taking advantage of it in competitive situations, some of us felt keeping the exploit private was unfair and counterproductive.

With the assistance of Marcus Trevino, tournament director at the Texas Pinball Festival and Houston Arcade Group and Josh Tidmore, I did some research and discovered the exact nature of this bug, which I’m revealing in the video below.   I’m doing this in hopes of making everybody aware of what the bug is and how to spot it being exploited.

Note that it’s NOT easy to even get to the point where it can be exploited.  It would take a pretty experienced player to use this glitch, but it’s definitely doable and very profitable when executed.

In a nutshell, the exploit has to do with the second phase of Emerald City Multiball Jackpots.   In order to use the exploit you do the following:

1.  Start ECMB (Emerald City Multi Ball) by lighting all the character letters and locking 3 balls in the center/right ramp.

2.  Complete the first phase of ECMB jackpot shots by hitting a character rollover and then shooting the right/center ramp.   After all three characters are collected, you then shoot the throne room to approach the Wizard.

3.  The second phase involves rolling over each character button (Tin Man, Scarecrow, Cowardly Lion) and then shooting the throne room to collect the jackpot/reward

You’re supposed to hit each character + throne room to get a jackpot.

The Jackpot starts at 20k and then increased by 10k for each subsequent Jackpot, so ideally completing the second wave would yield:

20k + 30k + 40k = 90k total points for all three character jackpots in the second phase.

However, if you avoid hitting the second and third character rollovers, and instead keep shooting the throne room, you can rack up consecutive, cumulative jackpots in perpetuity (20k + 30k + 40k + 50k + 60k, etc.) theoretically scoring endless amounts of points and jackpots that keep increasing.

 

Recommended mods to Bally-18/35 and Stern solenoid driver boards

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In today’s episode, I go over some standard, recommended modifications to the Bally-35 series solenoid driver board. There are over 60 popular pinball games that use this hardware setup and these quick modifications will help make the game run better and more-reliably. They involve adding three jumpers to the board. Whenever I have a chance to work on one of these boards, I do these mods.

Here are some front and back pictures of both Bally and Stern Solenoid driver boards. The black wires are the mods. The other colored wires are done by operators having to do with the coil lockout relay.

Bally Solenoid Driver board
Stern Solenoid Driver Board

Stern Meteor Pinball – First Look at a new, heavily-played pick up

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These days I’m pretty backed up on repair/restoration, but there’s always a “magic number” that’ll get me in gear to pick up a game. And when someone wants to reclaim their dining room or spare bedroom, I’ll do my best to help them out, as was the case with this “heavily-loved” Stern Meteor pinball game. I pop the hood on this baby and we take a look and see what’s going to be involved in getting it playable and in better condition..

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

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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.

flash_ic
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.

First Look: Williams “Flash” and Gottlieb “Grand Slam”

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Here is a quick video of two new machines that are in the shop to be brought back to 100%. Usually I run across games that are not this nice. This was a pleasant surprise. Take a look along with me as I examine the games after unloading them.