Scores Won't Advance More Than a Couple Steps

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Case Study Summary
Game Parade
Games Applicable To most games with advancing odds/scores
Source Bob K
Problem Reported scores won't advance beyond the 6 level, but extra balls work fine
Fix confirmed


Most of the games have advancing odds/scores. The earliest machines had a single score unit which stepped up randomly during the spin cycle, and later games with colored lines/sections had three or more score units - one for each color.

Although Parade has colored lines, it was in the transition period and only has one score unit.

Like most of the stepper units in the machine, the score unit resets when the shutter panel opens, and immediately steps up once. If it fails to make the first step, no score lights will come on and people know there's a problem. That gets the scores to the initial 4 level.

The score unit is guaranteed to step one more time (at least) to the 6 level on the next coin/credit played, but after that you are at the mercy of the proportioning circuits and the randomness of the spotting wipers and mixers.


Parade score circuit.jpg

Parade score circuit

Above is an excerpt from the schematic showing the circuits involved with stepping up the scores (red and purple) and extra balls (yellow).

Score unit step-up is fairly complex because the circuits take into account factors like the current score level, what features are enabled, and if credits have been won recently. See how it works for an incomprehensible look at what is going on.

The short version for this case is that scores will step up at least once per machine spin cycle until the odds reach the 6 level, which happens to be on the second coin/credit played. The purple circuit takes care of that.

After the odds reach the 6 level, the score disc itself (roughly in the center of the image) disconnects the purple circuit and connects the upper red rat maze of circuits instead. At this point, score advance depends on:

  • red/green double/tripe/quadruple scores enabled
  • position of mixer #2 rotor wipers
  • whether hole #2 is spotted or not
  • whether magic squares are enabled, and which ones
  • whether top/bottom extra lines are enabled
  • mixer #3 rotor wiper positions
  • once the scores are at least 8, the spotting disc wipers (orange circuits)
  • mixer #1 rotor position
  • reflex unit wiper position

Since the purple guaranteed step-up circuit is working, the circuit path from the score unit step-up coil to the score disc is ok. That eliminates a couple switches from the list of possible faults.

Inspection Debug Procedure

Bob simplified things a lot because extra balls are working. Extra balls share a lot of the circuitry. The unshared stuff is shown in yellow.

The primary changes caused by flopping to extra ball mode are:

  • an EB trip #2 relay switch adds in the score disc and mixer #4. The effect is to reduce the odds of getting an extra ball when the scores are higher
  • EB trip #1 relay switch bypasses mixer #3 every other spin cycle through alternator cam switch 9C. The reduces the penalty for having lots of features enabled.
  • another EB #1 trip relay switch disconnects the score circuits and connects the extra ball circuits. It wouldn't be cricket for the scores to advance while playing for extra balls. This is a critical switch and should be checked to make sure it's operating properly.

Voltmeter Debug Procedure

Assuming there is nothing obvious when inspecting the extra ball trip relay switches, by far the simplest way to find the problem is with a voltmeter. You set the voltmeter so you can measure 50V AC, and connect one meter probe to fat orange wire #70 (which is off the bottom of the schem image, but it's connecting to almost all the coils in the game, so you can clip onto it on whatever coil is handy. In this game, the trip bank reset coil is 120V, so not that one!).

With the other meter probe, you start looking at all the places marked with a green test point. Life is a lot simpler if you have the manual, because most of the units and relay switches are documented. A good place to start is the green test point at the upper right. You should see 50V here most of the time. To make life even easier, wind back the reflex unit to it's full reset position and you should get 50V here all the time.

Assuming you have 50V, move to the next test point on the center blade of the extra ball #2 relay switch, and keep moving through the circuit until the 50V disappears.

The gotcha is that the 50V is supposed to disappear sometimes. That's what the mixers are doing. When you get to a wire coming out of a mixer, and it does not have 50V on it, try turning the mixer rotor backwards one position at a time until the 50V appears. If you turn the rotor at least 24 positions and never see the 50V, the rotor wipers are the problem.

Given that things work when the yellow byass circuits are active, the likely problem is in the extra ball trip relays #1 and #2 switches that switch in the yellow circuits. The next likely problem is the wiper fingers on the score disc is making bad contact when the score disc is at the 6 level.

The likely problem spots are circled in blue.


Bob says:

I was able to locate the E.B. Trip #1 switch and it was defective, which I will describe below, and I have been able to rig it to work fine now. All features appear to be working normal.

EB trip relay #1 is located just above EB trip relay #2, and they are both connected by a metal bar so that when extra balls are desired, both relays trip to send juice another way. Well, the bracket (I hope I am using the proper terminology) between the 2 switches seems newer than the rest of the various switches in the area - in fact the entire switch #1 only seems newer, so this must have been replaced at some time.

The bracket wasn't tight enough or straight enough, so there never was any contact with wire #27-7 to #52-6, so there never was any juice going to the score disc above the 2nd level.

I was able to put a small piece of cardboard, for the moment, between the metal bar bracket and EB switch #2, so that when it wasn't tripped, in EB #1, wire #27-7 made contact with wire #52-6. When extra balls were desired, both switches are pulled back, and different contacts are made.

Success. Now I have to figure out how to make the fix permanent.

Bob needs some pieces off a parts machine. Even when there is no coil under the second E.B. trip relay, there should still be a relay plate that the switches sit on. The connecting bar is sometimes under this coil-less plate, and sometimes fastened to the top of it.