OK, I'll bite. I happen to have this schematic, so I can summarize the sequence for you. I know your machine has a disabled R relay, however I will describe its original operation in my description for completeness. Before we get into the reset sequence, though, we need to know about the behavior of the relays in your machine.

RELAY TYPES
---------------
There are two basic types of relays in your pingame. One type is the momentary relay, and the other type is the interlock (latch-trip) relay.

A momentary relay has only one coil, and is only in the actuated (active) state when its coil is energized. Whenever its coil is not energized, a momentary relay drops out to the non-actuated state.

In contrast, an interlock relay has two coils, one for latch and the other for trip. An interlock relay can be put into the latched state via a short electrical pulse to the latch coil, and it can be put into the tripped state via a short electrical pulse to the trip coil. An interlock relay remains in the most-recently selected state even after the selection pulse has come and gone. Also, an interlock relay receiving a latch pulse when it is already latched will remain in the latched state, while an interlock relay receiving a trip pulse when it is already tripped will remain in the tripped state. In this way, an interlock relay functions as a memory device, persisting in the state that was most recently selected via one of its two coils.

THE CONTROL BANK
-----------------------
On Gottlieb games of this era, there is a long bank of interlock relays sharing a common frame, mounted on the bottom board. This bank of relays is called the control bank. All of the relays on the control bank share a single latch coil, commonly called the bank setup coil or bank reset coil. When the bank setup coil fires, it causes all of the relays in the bank to become latched. In addition to this shared latch coil, each relay has its own trip coil, so each relay can be placed into its tripped state individually. The control bank only contains those relays that must all become latched when a new game is started, and that may (or may not) trip a maximum of one time (and then stay tripped) for the duration of an entire game. None of the relays on the control bank can ever be returned to the latched state while a game is in progress.

COIN DOOR CIRCUITS
-------------------------
OK, now let's look at the coin door relays. On Gottlieb games of this era, the coin door circuits operate at line voltage (115 VAC). This is to enable the coin door circuits to power up the machine if it is off when a user inserts a coin or presses the replay button. That may seem like an odd feature from the standpoint of modern machines, but this was a normal and expected behavior of pingames from the mid-1930s through the mid-1960s.

THE REPLAY BUTTON
-----------------------
When you push the replay button, you are completing the 115 VAC circuit to the E (replay button) relay coil, which pulls in. The E relay is a momentary relay. Switches on the E relay lock the relay in, and also energize the K (coin chute) relay. The K relay is a momentary relay. Switches on the K relay energize the primary of the main power transformer if it is off, which immediately supplies 30 VAC to the R (115 volt hold) relay. The R relay is also a momentary relay. From this point forward, the R relay will remain energized, and will maintain the primary voltage connection to the transformer until line power to the game is removed via the anti-cheat switches, the tap-off switch, or by unplugging the machine. Machines of this era did not ship from the factory with a physical on/off toggle switch installed. Once the R relay drops out, the machine power will remain off until it is re-established by the actuation of one of the coin circuits.

THE E RELAY VS THE K RELAY
----------------------------------
So, on this game, the function of the E relay is primarily to energize the K (coin chute) relay, the K relay being what initiates game reset when a coin is inserted. The K relay can be pulled in by itself by inserting a coin, but the E relay will always energize the K relay, so the E relay will never be pulled in by itself to start a new game.

From the standpoint of starting a new game, the only difference in operation between the E relay and the K relay is that the E relay will only work (that is, the replay button will only work) when the score motor is at the home (normal) position, there are credits on the replay unit, and the game is not in the first-ball state with both players set up to play (explained in detail later).

The only other function of the E relay that makes it different from the K relay is that, if the E relay is pulled in, it will cause one credit to be subtracted from the replay unit when a new game starts. The K relay pulling in by itself will not cause a credit to be subtracted from the replay unit. So if there are credits on the machine, and the user inserts a coin, the game will start but the user will not lose any accumulated credits.

Well, that's a whole lot of technical info, and we haven't even gotten into a discussion of the actual game reset process yet. But with all of that out of the way, we can now focus on what happens each time the K relay is pulled in, which I will go over in my next post.

- TimMe

THE SCORE MOTOR CYCLE
------------------------------
Before we dig into game reset, there is one more thing we need to look at, which is the Gottlieb score motor cycle. Many functions on a pingame require a sequence of individual operations that will execute in a specific order. The score motor, with its array of switches, is the device that provides this capability.

The physical layout of the Gottlieb score motor was designed to make it cheap to produce. Unfortunately, this also made it difficult to understand what was happening with regards to the timing of the various motor switches. Fortunately, the motor timing is actually pretty straight-forward. Each score motor cycle provides a fixed serial train of five pulses. For each of these five pulses, there is a companion masking pulse that occurs at the same time as the main pulse, overlapping that pulse entirely. Depending on the timing requirements, circuit wiring in the game may use the five pulse train directly, or it may combine the five pulse train with one or more of the masking pulses to generate a subset of pulses that occur at specific times during the cycle. This is especially useful when the pulse of one circuit needs to occur in a specific timeframe relative to the pulse of another circuit. A score motor circuit may also use one or more of the masking pulses directly, in order to provide a longer electrical pulse than what is generated by the five pulse train.

The way that score motor switches are identified on the schematic doesn't make it any easier to understand the motor timing, either. The score motor consists of a horizontal cam set that has three main levels called A, B, and C, with A being the lowest level. Many Gottlieb cams often have one or two additional cam levels above level C (levels D and E). In addition to the levels, there are several fixed switch positions around the outside edge of the cam set numbered 1, 2, 3, and 4. Therefore, a score motor switch labeled 1A on the schematic is a switch riding the A level cam, at switch location 1. Here is a chart showing the timing for most of the Gottlieb switch positions:

Gtb_Motor_Chart (resized).JPG

As you can see from the chart, the motor switch identifiers seem rather random in relation to their timing. However, there are a few things that are consistent. The A cam level always provides the main five pulse train, with switch position 1A being the one used during game play. (The 4A position is only used for score reset on some machines.) The B cam level provides a couple of masking pulses, and more importantly, the B level always provides a short pulse at position 2B that happens at the very end of each score motor cycle. That 2B pulse is always used to release locked-in relays (more on this in the next paragraph). The C cam level is always used for masking pulses, except for the 1C position which is always used as the score motor home (normal) position. You can also see from the chart that on games where the first pulse of the 1A pulse train needs masking, a cam with a D level is required.

OK, let's take a closer look at the purpose of that motor 2B switch. There is one fundamental operation using momentary relays in relation to the score motor that appears in every pingame. Here is an example of how it works. Let's say we want some feature (we'll use scoring 50 points) to be available in the machine. We will need to hard-wire that capability into the circuitry, but we only want it to be active at the appropriate time. So, we'll put a momentary relay into the machine and we'll call it the 50 point relay. We'll wire this relay so that it gets energized by a playfield target switch marked "50 points." When the ball hits that target switch, our relay will briefly close. That, of course, won't do much. However, if we wire a switch on the relay itself that will energize the relay coil, then when the ball hits the target switch, and the relay briefly closes, the switch on the relay will close, and that will keep the relay energized. This is called a lock-in switch.

OK, now our 50-point relay locks-in when a ball hits our target. With the relay locked-in, we can add a second switch to our relay that causes the score motor to run. We can also add a third switch to our relay that connects a 1A motor switch to the 10 point score unit. So now when the relay is pulled in by the target switch, the relay will lock itself in, the motor will run, we'll get a five pulse train from the motor 1A switch that will step the 10 point score unit 5 times, and that will score our 50 points. So far, so good. But now we have a bit of a problem. Since the relay is locked in, the score motor will run forever, and we'll just keep racking up points, 50 at a time. Fortunately, we have the motor 2B switch to solve this problem. The motor 2B switch is normally closed, and it briefly opens just before the score motor cycle ends. We can wire the lock-in circuit for our relay so that it goes through the motor 2B switch. That way, at the end of the score motor cycle, the 2B switch will briefly open, the lock-in circuit will be interrupted, our momentary relay will drop out, the lock-in switch on the relay will open, and the score motor will stop after just one score motor cycle.

Once again, a lot of information, but still nothing on the reset circuits. Well, obviously something as complex as game reset will be making extensive use of the score motor, so it's probably good to know what it's doing. In my next post, we'll finally start looking into the details of game reset.

- TimMe

You're welcome!

OK, as I explained in post #2, the K (coin chute) relay is actuated when a coin is inserted, and it is the K relay that initiates game reset. The E (replay button) relay is an alternate way to actuate the K relay, using the replay button instead of a coin. From this point forward, we'll look at game reset from the standpoint of the K relay only.

Also, note that all two-letter relay IDs with a second letter of "B" indicate an interlock relay located on the control bank, and all one-letter relay IDs indicate a momentary relay, so these distinctions will not be mentioned in the circuit descriptions.

NORMAL GAME START
-------------------------
Let's assume that the machine is sitting in the game over state after a normal one-player game has been completed. In this situation, the XB (game over) relay will always be tripped, and the PB (second player) relay will always be latched. Also, the ZB (first ball) relay will always be tripped, and the SB (start) relay will always be latched. We'll be looking at each of these relays in detail a bit later.

When the K relay is actuated, an N.O. switch on the K relay locks it in via the motor 2B switch. Another N.O. switch on the K relay starts the score motor running. Still another N.O. switch on the K relay, via a motor 1A switch and a motor 2C switch, generates a timed pulse (the second pulse of the five pulse train). This pulse trips the SB relay through a closed switch on the ZB relay, and it also trips the PB relay, and it also pulses the total play meter. (see schematic section 11-D/E/F).

START RELAY - TILT CLEAR AND BALL COUNT RESET
----------------------------------------------------------
As soon as the SB relay trips, a make/break switch on the SB relay opens to kill power to all of the playfield coils and the T (tilt) relay. The other side of this make/break switch closes and supplies power to the H (30 volt hold) relay. This ensures that the game is cleared of any tilt state during reset. (7-I on schematic).

At the same time, another make/break switch on the SB relay opens to kill power to the XB (game over) relay, the O and P (score control) relays, and the B (add balls played) relay. The other side of this make/break switch closes and supplies power to the score motor. This ensures that the add ball count/game over functions are disabled, and that the score motor runs non-stop for the remainder of the reset cycle. (15-H on schematic).

At the same time, yet another N.O switch on the SB relay immediately resets the balls played unit to the zero position, and also pulls in the D (reset) relay if any of the six score units are not at the zero position, to initiate the score reset function. (see schematic section 16-D/E/F). For this scenario, we'll assume that several of the score units are not at zero, so the D relay does pull in.

START RELAY - COIN DOOR LOCKOUT
------------------------------------------
There are two other switches on the SB relay that are actuated at the same time as those mentioned above. Both of these switches are in the 115 VAC section of the schematic. An N.C. switch opens to kill power to the replay button and to the coin switches. This is to prevent the game start from being triggered again while the game is already in the middle of a reset cycle (18-D on schematic). The other switch is the SB armature switch (17-G on schematic). It closes when the SB relay is tripped, and it enables the bank setup coil to be actuated. We'll be getting back to this switch a bit later. For now, it has no effect, because the D relay is pulled in, causing an N.C. switch on the D relay to be open (17-E on schematic), which prevents the bank setup coil from getting power.

D RELAY - SCORE RESET
----------------------------
There are six N.O. switches on the D relay that are now closed. Three of these switches connect a motor 1A switch to three of the score units, while the other three switches connect a motor 4A switch to the other three score units (12-G on schematic). Score reset pulses from the motor 1A and motor 4A switches now begin to step the score units forward toward zero. As the first score motor cycle of the reset ends, the K relay drops open via the motor 2B switch, but the score motor continues to run because the SB relay is still tripped.

With the D relay pulled in, the score units continue to step forward toward zero via the motor 1A and 4A switches. Looking at the chart in post #4, you can see that the motor 1A and 4A pulses are interleaved. This allows all six score units to be stepped forward during each score motor cycle. It isn't possible to step all six score units at the same time, because the large amount of current needed to fire all six score drive coils together would overload both the transformer and the motor switch contacts. So, the 4A switch position is used to provide reset pulses for three of the score units. Since the 1A and 4A pulses are interleaved, only three of the score unit drive coils are ever energized at the same time, preventing an overload.

On each score unit, the reset pulse being sent to it via the D relay switch is routed through a runout switch on that score unit. This runout switch is closed at all score unit positions other than zero, and it opens when the score unit is at zero. So, when each score unit has stepped to its zero position, its runout switch opens, keeping it at zero while other score units are still resetting.

When all six of the score units get to zero, the score reset function is complete, and the remainder of the reset cycle can proceed. Details on that will be covered in my next post.

- TimMe

Thanks @Carlo45! I'm glad this is information is helpful. @Paulace, I will try to post some schematic snippets at some point soon, after I finish the description of the game start.

DETECTING SCORE RESET COMPLETION
---------------------------------------------
OK, we're at the point in the reset cycle where the tripped SB relay is keeping the score motor running, and the D relay is pulled in because the score units are being stepped around to zero. We know that on each score unit, there is a runout switch that stops the score unit from stepping once it reaches zero. There is also a second runout switch on each score unit that is closed at all positions from 1 to 9, and that only opens when the score unit is at zero. This second runout switch is used to keep the D relay energized. All six of these runout switches are wired in parallel (16-F on schematic), so the D relay will remain energized as long as any one or more of these are closed (that is, any score unit is not yet at zero).

CONTROL BANK SETUP
--------------------------
As soon as all six of these score unit runout switches are open (all score units are at zero), the D relay will drop out. This allows the N.C. switch on the D relay (E-17 on schematic) to close, which enables the circuit to the 115 VAC bank setup coil. Note that there is another switch (just to the right of the D switch on the schematic) on the balls played unit. The balls played unit switch only closes when the unit is at the zero position, which it should be by now because the unit was reset when the SB relay first tripped. This is a safety switch that ensures that the control bank setup coil won't fire (that is, the game won't come out of reset) unless the balls played unit really is at zero as it should be.

As the score motor completes its second or third cycle (depending on how many steps it took to get the score units to zero), the motor 4C switch will close (17-D on schematic). You can see from the chart in post #4 that motor 4C is a long masking pulse that occurs almost at the end of the score motor cycle. This long pulse provides a good solid shot of current to fire the large bank setup coil such that it has enough power to latch all of the relays on the control bank.

When the bank setup coil fires, it latches the QB (game over), ZB (first ball), XB (last ball), and PB (second player) relays. It also latches the 1B and 2B (first and second player thousands) relays if those had been tripped by high-scoring players during the previous game. All of these relays need to be latched in order to be in the correct state for the start of a new game. And most importantly, the SB (start) relay is latched as well, which is what will take the game out of reset. However, before we talk about that, let's take a closer look at the operation of the SB armature switch (17-G on schematic).

THE SB ARMATURE SWITCH
-------------------------------
The SB armature switch is literally a switch that rides the armature of the SB relay. In order to do this, it needs to be attached to the control bank in a special position that puts it under the bank, so you usually need to turn the bank over to see it. This switch is both rather dangerous to work on with the game plugged in (it's on the 115 VAC circuit) and is difficult to deal with if you need to clean and/or adjust it. So naturally the question is, why put this switch in such a weird place? To answer this question, we need to know in some detail how the bank relay mechanism works. We'll use the SB relay as an example, although this discussion applies to the operation of all the bank relays.

The armature of the SB relay is simply a spring-loaded flat metal plate that gets pulled in by the SB trip coil when the trip coil is energized. The SB relay also has an actuator, which is a spring-loaded hinged metal lever with plastic arms. The actuator can be in either the latched (up) position or the tripped (down) position. In the latched (up) position, the armature is pulled away from the trip coil by its spring, and a tab on the armature holds the actuator up. In the tripped position, the armature has been pulled against the trip coil by the coil magnet, moving its latching tab out of the way so that the actuator can be pulled into the down position by its spring. When the actuator is in the down position, its plastic arms actuate the switches of the relay. Also, in the down position, the actuator is designed to keep the armature pressed up against the trip coil, even though the trip coil is no longer energized.

To return the relay actuator to the latched position, the bank setup coil needs to fire. The bank setup coil plunger, via a crank arm, operates a long metal bar that pushes all tripped relay actuators upward, raising them high enough to become latched again. As mentioned previously, all of the bank relays share one bank setup coil, so all of the tripped relay actuators will get latched at the same time from a single operation of the bank setup coil.

As the actuator is raised up to put it back into the latched position, the plastic arms at some point move off of the relay switches, allowing the switches to return to their normal (non-actuated) positions. When the actuator is finally raised up enough to be in the latched position, the armature will be released, allowing the armature spring to pull the armature away from the trip coil so that the tab on the armature can latch the actuator in the up position again. At this point, with the relay officially latched, the plastic arms of the actuator must be totally clear of all relay switches.

Obviously, all of the switches of a relay are supposed to opened and closed by the plastic arms on the actuator. But if we were to put the SB armature switch in the usual position, what would happen? Let's temporarily rename this switch the bank setup switch, move it to the usual position, and see.

OK, now we've got the bank setup switch positioned in the regular switch stack of the SB relay. The SB relay is tripped, so the bank setup switch is closed. Because the bank setup switch is closed, when the motor 4C pulse occurs, the bank setup coil will fire. The SB actuator starts to rise up, moving toward the latched position. However, at some point during this upward movement, the bank setup switch will need to open. In fact, based on the design of the relay, we are supposed to ensure that the bank setup switch will be reliably open before the SB actuator is in the fully up (latched) position. This will cause a big problem. As soon as the bank setup switch opens, the power to the bank setup coil will shut off. So by design, using this circuit guarantees that the bank setup coil pulse cannot be made to last long enough to return the bank relays to their fully up (latched) position.

The way Gottlieb solved this problem was to move this one switch so that it would ride the SB armature. We know from the mechanical design of the bank relay that the armature always sits away from the trip coil when the SB relay is latched, and that the armature is always held up against the trip coil when the relay is tripped. The SB armature switch is oriented so that it is closed when the armature is against the trip coil (relay is tripped). Once the actuator has been raised up high enough to physically latch, the spring-loaded SB armature pulls away from the trip coil, latching the actuator and also pushing against the armature switch to open the switch. By using a switch operated by the armature, we can ensure that the switch will stay closed until the actuator has been raised up high enough to allow the relay to physically latch, which is exactly what we need for this circuit to work correctly.

This may not be the most elegant design solution for this problem (there are other ways to solve this) but this is how the Gottlieb engineers did it on many of their games through the 1960s, so we need to understand it. Gottlieb did eventually eliminate the SB armature switch (and in fact, the entire control bank) in the 1970s, to streamline their design and also to cut production costs.

With the operation of the SB armature switch explained, we can now look at the completion of the reset cycle, which I will cover in my next post.

- TimMe

RESET COMPLETES AND THE GAME STARTS
-------------------------------------------------
OK, we're now at the point where the reset is nearly done. The bank setup coil has just fired and has latched all seven relays on the control bank, including the SB (start) relay. The score motor stops at the end of this cycle, because the make-break SB switch (at 15-H on the schematic) is no longer supplying power to the motor.

On the ball trough path, there are two rollover switches. One of these switches is positioned so that the ball rolls over it just after the ball drains. This switch advances the balls played unit. However, the ball is already resting at the ball gate, downstream from this switch, so the switch won't be actuated (and no ball count will occur) when the ball is released to start game play. The ball will need to be played and will need to drain before it will roll over this switch for the first time after the game has been reset. That's not a problem, because the zero position of the balls played unit is actually the player 1 ball 1 position. So, the balls played unit is already at the position it needs to be for the start of the new game.

The other trough rollover switch is positioned so that the ball rests on it whenever the ball is stopped at the ball release gate. As soon as the bank setup coil fires and latches the XB (last ball relay), an N.C. switch on the XB relay (13-H on the schematic) closes and allows the ball release gate to open, delivering the ball to the ball lift. Also, the make-break switch on the SB relay (7-I on the schematic) has been returned to the non-actuated position, so that switch is now providing power to the playfield coils. At this point, the machine is on player 1 ball 1, and is ready for the player to shoot the first ball.

ADDING PLAYER TWO
------------------------
If a second player is desired, dropping in a second coin (or pressing the replay button again) will cause the K relay to energize and lock-in again. This will once again start the score motor running, and the resulting pulse from motor 1A and 2C will increment the total play meter and will also trip the PB (second player) relay. However, this time the SB relay will not trip, because the ZB (first ball) relay is in the latched position, which means the ZB switch in the circuit to the SB relay (11-F on the schematic) will be open, preventing the SB relay coil from getting power. At the end of one score motor cycle, the K relay will drop out via the motor 2B switch, and the game will once again be ready for play, but now with two players set up instead of one.

At this point, if the replay button is pressed again, nothing will happen. That's because the three parallel enabling switches from relays H, ZB, and PB that are in the button circuit (17-F on the schematic) will all be open. It is possible to drop in another coin, which will still energize the K relay and cause one score motor cycle. This will increment the total play meter and pulse the PB trip coil again, but since the PB relay is already tripped, the game state won't change. It's interesting to note that while the circuitry protects the player from pressing the replay button a third time (and losing a credit for nothing), there is no protection on the coin chute, because it's assumed that people will be more careful about putting money into the machine than they will be about pressing the button.

GETTING THE GAME TO DO A FULL RESET
----------------------------------------------
It's clear that the purpose of the ZB (first ball) relay is to put the game into a unique state after a new game is started, but before the first ball is played. In this unique state, the machine will add a second player rather than do a full reset if the K relay is energized. Under normal conditions, the ZB relay will trip the first time any single point score is made on the machine, which will happen as soon as the first ball is played. Once the ZB relay is tripped, the machine will no longer be in the unique state, so if the K relay is energized after a ball is played, the SB relay will trip and a full reset will occur.

But, what if we set up a two player game, and then unplug the machine and plug it back in before we even shoot the first ball? In this case, the machine needs to do a full reset when the K relay is energized. But, the PB relay is tripped, and the ZB relay is still latched, so we might expect the replay button to be locked out. For this situation, an H relay switch has been wired in parallel with the PB and ZB relay switches that are in the enabling circuit to the replay button (see 17-F on the schematic). This H switch will be closed when the H relay has dropped out, ensuring that the replay button will work after the game has lost power. A different H relay switch has also been wired in to the circuit to the SB relay that bridges the open ZB switch (11-F on the schematic). This H switch ensures that the K relay will always trip the SB relay after the game has lost power.

- TimMe