If you are troubleshooting an AC circuit, even though it is true that current flows both directions (AC means alternating current), by convention the reference current directions are often chosen so that all currents are toward ground. This often corresponds to the actual current direction, because in many circuits the power supply voltage is positive with respect to ground. Even though current physically flows in both directions in an AC circuit, we will often imagine the positive/hot side of the circuit as the top of the mountain with potential energy that flows "downhill" to ground.

It is probably more helpful to consider events when troubleshooting - i.e. a certain switch must be closed first to provide a path to the next switch or device. If I know a certain relay provides a switching path for something that is not happening, the first thing I would do is see if the relay is tripping, if it is tripping the coil on the relay is getting power like it should, and therefore my problem is within the switch path of that relays contacts, or even the relay switch contacts themselves. If the relay is not energizing my problem is within the path of the relay coil because the event of the coil energizing must take place first. Ultimately, for most problems the thinking would be "A has to happen for B to happen, and so on"

An alligator jumper is your friend. Classic circuit, 4 reels must be on zero and their zero position switch closed for a part of a reset seq to be complete. All the reels are on zero yet the motor runs and runs. Solution, take an alligator jumper and clip it on one end of the chain and move it down switch to switch until the db relay pulls in, you found your dirty switch...

Or BankABall, 7 daisy chained switches on the relays in the head, which is the dirty one preventing the special?

Or game remains in tilt, on of three slam switches really not closed? which one? Jumper them.

Last night my Surfer would hold in the tilt hold, ran a jumper from 30v to the relay as a work around while I fixed something else. Then I noticed later same slam switch circuitry had a run to the coin lock out relay...and what do most of us do? disconnect the coin relay on the door because they are always burnt. And it happened to be a "loop thru" (not the end of the circuit but two wires on 1 lug), my visual inspection showed the previous repair dude forgot to twist the two together leaving my slam circuit opened. Fixed.

And lets say you want to verify all the bulbs of the match circuit, either find the stepper and advance it by hand in game over or use a jumper and run down the bulbs...

Also, one thing to note, the "state" of the cir diagram is ball one, ball in shooter lane waiting to be plunged...

Ken

I found this "How to read Schematics" audio pres by Chris H extremely useful:

http://www.google.com/url?q=http%3A%2F%2Ftinyurl.com%2Fcur9jvq&sa=D&sntz=1&usg=AFQjCNFplbCEy4MtBkzMUYLd_cOWQnfACw

Neither, actually. The schematic is only showing a point of reference for the switches in that particular state: the game completed reset, the first ball is ready to plunge, and the game was turned off. It's only capturing a stable state of the machine. They could have chosen many other stable states, but when servicing games usually the power is off, so this one worked for them.

If you turned the game back on following that, it won't be able to play. It will need another reset first.

Actually, they won't. The Coin Lockout will energize, but Hold and Tilt Hold need the Start and Reset to energize to complete the path to them again.

When reading Gottlieb schematics, you want to follow the path towards the coils (i.e., you want to follow the path towards the thing you want to have happen - energize a coil, the score motor, or a bulb). It's usually easier to start at the coil (or bulb or motor) and then read the path backwards to see what switches are needed to complete the path.

The right side of the schematic is the 25V section and is for the coils. The left side is the 6V section and is for lighting. The right side is generally depicted as a collection of parallel paths (like a rungs in a ladder). Each coil has a path that starts at the transformer, goes counterclockwise through some collection of switches to reach the coil, and then returns to the transformer.

The left side is the same, but it flows clockwise (with the bulbs and coils all depicted down the 'middle', so its laid out in a butterfly pattern).

Dots indicate logic paths that intersect ('dot OR'). Lines that cross are just a drawing artifact and do not indicate any relationship.

There was also this thread:
https://pinside.com/pinball/forum/topic/reading-schematics-how-i-learned-maybe-it-will-help-others#post-1538928

I thought it was powered on state rather than powered off state?

They started noting it on later schematics.

GtbSchemNotice.jpg

One thing to keep in mind. When unplugged:
All "normal" relays will release to its normal unpowered state.
Latching type relays, if latched... will remain latched in an unpowered state.

Another thing to keep in mind when diagnosing problems is to consider what works in a particular circuit and what doesn't work.
That is a way you can narrow the problem down and resolve problems quickly.

Take my circuit below for example.
The problem is coil "A" does not work (What coil A actually does in the game is irrelevant here). The coil checks good.
It is easy to overlook the other associated circuits and believe you must check switches 1, 2, 3 and also the Score motor switch.

*****-->Wrong!<--*****

A little bit of quick investigative work can save a lot of time and effort.
Running the machine, you notice coil "D" energizes according to the operation of the score motor switch. Because coil "D" is operating normally, you don't need to check the score motor switch.

Further investigation shows that coil "C" is also operating properly.
Because coil "C" goes through switch #3, you don't need to check that switch.

Continuing, you notice coil "B" also does not work. Ok, now you have noticed both coils "A" and "B" does not work.
The first switch you should actually clean/gap/check would be switch #2 because that is the next switch in line that operates both coils.

If coil "B" actually in fact -did- work, then the trouble is likely going to be with switch #1.
A little creative observation has considerably increased your troubleshooting efficiency.

1.png

This process of elimination by observation can be helpful in a lot of trouble circuits.
Consider the circuit below.
Let's say the trouble is the BX (Game Over) relay is not tripping.
Looking at the schematic it is easy to think you must check the switches I, U, maybe the coin unit, maybe the player unit, maybe the 3/5 ball adjustment and possibly the O switch.

Wrong!

Test the machine.
You can see the circuit is also part of the score reel reset circuit and drives the Player unit "Add Player" solenoid.
You already know the machine resets properly, it's just the BX relay doesn't trip so you've just eliminated all those switches and circuits up to the player unit rotor disk.
A quick look at the Player unit rotor disk and contacts checks good, so the only thing else is a switch on the O (Ball return) relay.

Zingo presto!
2.PNG

Hi Ramtuathal
when I have the question "what / which relay should be pulling ?" - I like to have a look at the "6VAC-section showing the lights (bulbs)" - maybe there is a switch drawn in the circuitry, named "ABC (relay)": I investigate on the "ABC-Relay" ...

Wen reading a schematic (I admit) sometimes I do not (truely) understand (Topic-AAA***) why "this wire" / "this switch(es)" are drawn in the schema (at this place). I might not (truely) understand why "this switch is drawn open (or close)".

Well, I once read (unfortunately I did not make a copy of that text): "Carefully checked and counterchecked "Reality-in-the-pin" and "drawing in the schema" - TWO switches were drawn in the schema, BUT NOT mounted in the pin ----- ONE switch was / is mounted in the pin, BUT NOT drawn in the schema".
I once red a "big discussion" on: "A switch drawn closed in the schema - should it be open ???".
We are human beeings - errors / faults / mistakes may happen ...

Topic-AAA***: Usually a game ends: The player(s) play all balls -> Game-Over.
BUT - think of: Player-3 plays his second ball - the ball rolls into a "Eject-Hole way up the playfield" - a blizzard destroys the local transformer-station -> the supply of 110 VAC is cut.
After the local transformer-station is repaired -> (the ball still is in that "Eject-Hole way up the playfield" (and there is no "Game-Over")): Pushing the Replay-Button MUST START a new game.
So if I do not understand a specific wiring - I do thinking "a blizzard has ...". Greetings Rolf

Ok, since I'm on a basic troubleshooting roll....

This process is a bit more involved than the method I previously explained but it can help find some difficult issues.
First I made a simple voltage tester out of two automotive lamps. The lamps are rated 12V so I connected a pair of identical (They *must* be identical) lamps in series so they don't burn out when connected to the games ~25V (12+12=24) and also long alligator clip leads. The lamps draw enough current to really test the circuit.
A modern digital VOM may not be accurate in troubleshooting current applications because DVOM's utilize such little current.
Also, the lamps burn very brightly and can be seen lit even when not in view.
Here's my crude tester setup:
Tester.jpg

Consider the circuit below. The coil tests good, all switches have been cleaned/gapped/checked. As a pure series circuit there is no process of elimination by observation mentioned in my last post.
1.png
You'll find that almost all coils in the game are connected by a common black buss. You can find this black wire(s) on one side of the coil and clip on one of the tester clips.
You will want to start on either end of the series switches (Not in the middle) and work toward the other end. You'll want to clip like this, and each of the red numbered dots represent a logical test point since it is after the switch:
2.PNG
First thing I'd do is find the correct score motor switch, locate the gray wire and clip the yellow tester wire onto the switch's solder lug.
I'd do what ever it is the machine should naturally do to get the coil to operate (Ring a chime, add a bonus etc) and see if my tester lights. If it does light then I will move onto the 2nd test point and put my yellow clip on the solder lug with the orange wire with a green tracer. Then operate the machine.
Suppose my tester does indeed light on the 2nd test point, so I will do the same with the 3rd and 4th points:

Upon testing, I discover the tester does not light on the 4th point. Double-checking that switch discovers nothing.
I would move my yellow tester clip to the other side of that switch, onto the solder lug of the yellow wire and operate the machine:
3.png

I discover my tester does not light. ...hmmm... No power to the switch.
I double check the wire is not broken from the solder lug etc. I consider if there may be anything else in the circuit that may cause a bad connection between test point 3 and test point 5. For example, if some of the switches are located in the cabinet on the bottom control board and the coil is in the head, then the connection would definitely pass through a Jones plug.

Here, in this hypothetical problem we found a bad Jones plug connection:
4.png

Pretty basic but maybe these might help someone.

I haven't seen this before, but THIS makes sense. I have been working on extensive analysis of my Bally Bon Voyage, going through every single piece of the schematic and figuring it out. I will have a write-up on it, but sometime later when I get time. But as of now I have about 90% of it in my head as far as understanding how it all works. I think the Gottlieb and Bally schematics are similar in many ways.

Anyway, I sorted through the whole schematic and agreed that it was shown in a state which would be after a game was started, then shut off with the ball ready to shoot (which I had read somewhere else). What drove me bonkers was that the power switch was shown closed, and this created an impossible situation because of the position of the game over relay (I won't go into all the details why here, unless you want to hear it). But, if you simply unplug the machine - now that makes sense. The power switch could be closed and this would be an accurate state.

On my schematic, it isn't perfectly consistent throughout as far as the shown state, although pretty close overall as far as I can tell. For example, the Ball Count Unit Disc is drawn with 1 ball to play, and if the game was just started and then shut off, it should be 5 balls left to play (because the jumper is drawn in the 5 balls per game position, not 3).

I'd think that was showing "Ball 1" (of 5) and not "1 ball left to play". The Ball Count increments from 1 to 5 (unless it's an add-a-ball game, in which case it does decrement).

Yes, this is correct, and BV is an add-a-ball Definitely shows balls left to play.

Edit - a bit more - at the beginning of the game during reset, the ball count unit is reset to 0, then stepped up to either 3 or 5 depending on the position of the adjustment plug. It has a max of 9 for additional balls that can be won during play.

Clay has a bit of a tutorial write up here:
http://www.pinrepair.com/em/index3.htm#schematic

Nice Steve. I'm making one of these up soon.

This is a good thread and I'm learning from it.

I'm trying to use 8 foot jumpers to troubleshoot a JitB that won't start up but I'm not sure exactly where to put the clips on the schematic below.

I need to test jump the circuit to the S start relay and coil. I would connect one end to the black common on the S start relay coil but I'm not sure where exactly to clip the other end for the circuit through the replay or coin switches.

Yellow highlights show where the S coil and two S relay switches are.

The color wires don't seem to match for the coin switches too. I can provide photos of the switches and relays in question.

Bruce

GitB S Relay.jpg

Hi Bruce
You are not interested to test the H-Tilt-Hold-Relay ? - Testing the H-Relay would tell You two things: 1) about "Playfield-Lights", 2) Does Your JitB has 24 VAC ready for Relays / Units / Score-Motor.

Well, using a Jumper-Cable is good - SOME Relays (H-Tilt-Hold-Relay / S-Start-Relay / others) can be tested with an "very easy test" - IF THE RELAY TO BE TESTED HAS A SELF-HOLD-SWITCH: You take a wooden stick and gently push onto the anchor-plate on that relay (You simulate: Relay gets initial current - it starts pulling (because You push onto the anchor plate)) -> the Self-Hold-Switch is closed -> the Relay should be pulling - having connection through the self-Hold-Switch.

Look at th JPG: Pushing onto the anchor plate of the S-Start-Relay -> the Self-Hold-Switch (yellow arrow) closes -> if the S-Relay itself pulls: fine / if the s-Relay itself does NOT pull: We must check the fuse and a couple of switches (and the wires itselfs) for connectivity. Greetings Rolf

Self-Hold-Circuitry-JitB.jpg

Bruce - please keep your JiTB issues in one thread... makes it easier to keep track of what you are trying to do and have done to troubleshoot so we can help you better

Woz, I was planning to share what I learned here in the JitB won't start up thread and because this is a schematic thread I was thinking I would ask how to troubleshoot using the schematic and jumpers but I probably should have kept the questions more "generic" instead of game related.

Should I continue here or ask schematic questions in the other thread?

Bruce

Hi Bruce
(My opinion) Ramtuathal started this topic - to post-11 everything was about "reading schematic". Again post-13 to post-16.
SteveFury post-12 is an excellent post --- post-12, post-18 and post-19: they should be in: https://pinside.com/pinball/forum/topic/using-schematics-and-8-foot-jumper-wires (also: other questions about USING Jumper-Cables).

My answer to Your question (post-18) "One Gator-Clip is on Lug-of-Coil-S-Start-Relay-side-colour-Black - where to use the other Gator-Clip of the Jumper-Cable ?": Any place that has a connection to "wire BLACK" / transformer-24-VAC-side-BLACK" (my JPG-post-19: the blue line). If You would jumper to (... red line) : You would make a short.

(again, my opinion) Ask specific questions on Your JitB in Your Jitb-Topic, write "insights / cognition / awareness / understandings" in https://pinside.com/pinball/forum/topic/using-schematics-and-8-foot-jumper-wires --- "good" questions in here would be like "What is the difference in "On-Off-Switch", "Bounce-Switch", "Anti-Cheat-Switch" ?". Greetings Rolf

I find it extremely valuable to have a computer scan of the schematic.

That way I can make copies of it and modify as needed when diagnosing a difficult problem.
If a computer scan wasn't possible and/or my computer skills weren't good then I'd make a bunch of paper copies of it.

As we know when a relay changes state, one or several switches associated with it also change state. The game reset sequence for example has several relays energizing, de-energizing and pulsing at secific times. It can be difficult for me to keep a mental note of all the various switch states at a given time.
That is when I make notes on the schematic copy. I highlight and redraw switches if I have to etc.

However the need to do those kind of physical notes diminish once you get used to the flow. You eventually learn how to track relay switch states with practice.

Rolf, I completely forgot about that thread! Will head over there to ask about using jumper wires.

Bruce

This is a good tip and your first diagrams are easy to follow.

This one is more complex when I look at it and I have questions about the schematic image you posted.

There seem to be a lot more circuits to the BX relay depending on what you're doing. Is the red circuit or path to the BX relay that I've drawn on your image correct?

Is the "Player Unit" a jones plug where you would have to clip on each side's lug to be sure the circuit's going through? Same with the "Coin Unit"?

SteveFury Schematic section.png

How about where you would clip the jumper clips? Is what I've drawn in blue correct? "1." being the first clip and "2." being the second clip on the tester.

Do you put the first clip on the common side of BX coil or the side towards the "O" switch and start with the second clip on the inside or outside of the "I" switch?

(What are P2G, P3G and P4G on your schematic image? I can't see the Relays, Coils etc list.)

Can you show a close-up of it so I can see how it's made? How do you manage it or hold it while testing? Do you put the wires with lamps over a hook?

Thanks, this is helpful.
Bruce

Hi Bruce!
You have drawn the correct circuit for the BX relay.
However the premise of the trouble was the machine resets correctly but the BX won't energize. Since the machine resets correctly and the "Add Player Unit' is operating, we can eliminate much of that circuitry. What's left is the Player Unit rotor, a switch on the "O" relay and the BX coil itself.
Suppose the Player unit was not advancing. It is such an important part of the reset sequence that I'd fix that first before the BX.

Since Jones plugs are not shown on the schematic I have to consider the location of the parts I am testing. There are 3 or 4 main sections connected by the plugs. If two parts are located on a different section than the other then it passes through a plug. The plugs *usually* don't fail but it may be a consideration.

It's just two automotive brake lights with the bases against each other then wrapped a few times with copper wire which is soldered to the socket bases. My leads are soldered to the bottom buttons as I drew them. I think I put a couple zip ties to hold the wire leads, to keep stress off where they are soldered. *I should* wrap electrical tape around the exposed areas so if it drops on a bad place it won't blow a fuse.
I don't use it very often, when I do then I just lay it on the bottom of the machine or somewhere in the head. They are super-bright when they light and can be seen anywhere near.

Another thing that I can find confusing when reading a schematic and its relation to my machine is wire color substitutions.

It doesn't help when the harness is shaded a uniform gray from dust/dirt for seeing the colors that have faded. That's another reason to take the time to clean harnesses in a refurb/rebuild.

Suppose I am working on a problem and need to identify the location of a particular switch on a full relay with 6 switches on it. The schematic says the switch I am looking for has a green wire with a slate tracer. I don't find any green wire with a slate tracer anywhere on the relay.

Double-checking for faded/dirty wire colors, (Sometimes colors are more preserved under a loom) there's definitely no green wire with slate tracer here.
Hmmm..... Some investigating may be in order.

*If the schematic says the switch is wired to a lamp or coil, then the easiest way to identify the wire is to see what wire color is soldered to the lamp or coil. You should be able to see the same wire color on the relay switch.
*If the schematic says the switch is wired to another relay, check that other relay. Perhaps that relay only has one or two switches on it. If that's the case then follow the process of elimination, comparing wire colors relay to relay. You can verify your suspected wire with an ohm meter.

Hi Bruce. I assume the "S" relay is not operating, and the coil itself is good.
I would first consider the process of elimination.
The start circuit is designed to be flexible with lots of coin configurations for the vending operator. Some configurations use the Replay or Credit unit, some configurations don't.

First thing I'd discover is whether the various methods (All coin slots etc) work or not. If all methods don't work then I'd look at the schematic and discover the common links between them.

If I discover, for example that it's really only coin slot #2.... Which is set for 1 coil 1 play then I'd study its schematic circuit and determine how coin slot #2 is supposed to work, and always consider if I can use a process of elimination again to isolate particular switches.

I personally consider using the lights as a last resort because other methods are generally easier and faster.

Hi
about the colors of wires "schema" <-> "reality in the pin" - Look at post-18, JPG at the bottom, left:
A wire "Orange" runs from "Score-Motor-Switch-1B" to "Switch on U-Relay" -> then wire "Black" ...
A wire "Orange" runs from "Score-Motor-Switch-1B" to "Switch on O-Relay" -> then wire "Brown" ...
If (if) U-Relay and O-Relay are monted in the pin "side by side": Maybe (maybe) the wire "Orange" is soldered on the "Switch on O-Relay" - and a short, blank (jumper-like) wire does connect this "Switch on O-Relay" and "Switch on U-Relay".
General on "Wire-colors": On some Williams-schemas there is that "wonderful" Text stamped onto the printed schema: "Due to wire shortages beyond our control, some wire colors may be other than indicated on wiring diagram" - lovely ? - example (in the corner D-1 / E-1): http://mirror2.ipdb.org/files/245/Williams_1977_Big_Deal_Schematic_Diagram_continuous.pdf

Important to know, example Jack in the Box: Gottlieb-Schemas have a list of Relais (used), example
"13E H A9738 AG 2A, 1B, 1C TILT HOLD RELAY" means: The Coil (A9738) of the Tilt-Hold-Relay is drawn in the schema at 13E - named "H", the relay is of commom type (AG) - on that Relay are mounted switches "Two switches of type-A = Normally-Open-Switch", "One switch of type-B = Normally-Closed-Switch", "One switch of type-C = Make-and-Brake-Switch".
It is helpful when You locate (all) these switches in the schema - for understanding the "succession / sequence in time" of the "Lifetime of a ball". And, on these switches there are wires soldered-on, these wires have color - having a look at (switches, colors) might help on the actual problem (by eliminating).

Very important: The main difference in the wiring (and therefore visible in the schema): Williams and Bally are wired "Style-Wms-Bally" and Gottliebs are wired "Style-Gtb" (these two words are my invention - they are NOT official !!!).

"Style-Gtb": Tranformer-Power-Side -> Fuse -> Switch -> (Switch) -> (Switch) -> Lug-on-Coil. And Transformer-Returning-Side -> wire -> Lug-on-Coil.

"Style-Wms-Bally": Transformer-Power-Side -> wire -> Lug-on-Coil. And Transformer-Returning-Side -> Switch -> (Switch) -> (Switch) -> Lug-on-Coil.
(Williams and Bally use 24 VAC / Bally use 50 VAC).

It is NOT so good for You to touch the "Transformer-Returning-Side" - if the pin is hooked-on 110VAC correctly: It will not harm You.

BUT !!! If You touch "Transformer-Power-Side" and through Your body current flows to "Earth": This can be deadly !!!

If You use Jumper-Cables: ALWAYS KNOW where You clip-on the Gator-Clamp - If you hook-on onto / into the POWER-Side: YOUR JUMPER-CABLE IS UNDER CURRENT !!!
Greetings Rolf

My first post as a Pinsider. I've read this thread tonight, and also the other threads referred to in this post. Thanks much for your contributions as I've learned quite a bit tonight that will help me in dealing with scoring problems in a 1974 GTB Far Out I purchased. I'm still in the inspection stage of this machine and have a couple of questions with regard to the schematics:

1. What is the best approach when GTB documents present conflicting information? In my case, the motor 2C switchdog was in the "L" position when I bought the game. The Far Out Installation Manual indicates the "L" position is correct for this stack, but the schematic motor switch table shows the "S" position as the correct one. Does it matter? Or should I place the switch dog in the "S" position to see if it resolves any of scoring issues, the main one being scores being recorded for Players 1, 2, and/or 3 in a 1-player game.

2. In looking at the relay table, does it follow that if a relay has X number of switches, then I should be able to find the same number of switches for that relay in the schematics? For example, in my game Relay N (10 point relay) has 5A switches (i.e. 5 NO switches) shown in the schematic's Relays table. It also has 5 switches, all open, in reality as it exists physically in the backbox. However, in looking at the schematic, I can only find an "N" switch in 4 instances: lock on switch for the N relay, ten point chimes, 9-position check for carrying over to hundreds, and add ten points. I've looked multiple times and I still don't see another use of an N relay switch anywhere in the schematic. Am I thinking incorrectly about this?

Thanks again. This site looks to be a great source of information. I've been in and out of the hobby for 10 years, mostly out. Well, I'm back in again.

PM

Hi Steve,
Glad I got it right. I'm learning here.

This is good to know too. I thought they were shown on the schematic.

I'm having trouble with this too. Seems some of the colors don't match the schematic or I'm not looking at the right ones.

This is a good tip. What do you use to clean the harnesses and wires? I've tried 91% ISO which seems to work but maybe there's a better way?

Thanks for the help here, Steve.
Bruce

Rolf, your posts are very helpful and I'm learning from them too.

Thank for taking the time to help us out here.
Bruce

Hi PM
the 5 switches on the N-10-Point-Relay are drawn: H-2, H-8, E-7, H-15, F-15 for to "let the First-Ball-Relay (pull) fall - it is in the Relay-Bank - it tells the brain of the pin: "Game HAS REALLY started - You brain are entitled to change from ball to the next ball (player). Greetings Rolf

Hi PM
welcome to "pinside.com". Far Out is my Number-One pin - great You have one too. For your (specific) questions on Far Out: Please start a new topic - following the Chris guidelines in here: https://pinside.com/pinball/forum/topic/how-to-efficiently-ask-for-pinball-repair-help-em

((My Far Out (pin and Manual) also has SCM-2C in "L-Position" - my schema also has noted "S-Position". I believe: A little error / mistake in the schema.
Your (post-31) "scoring issues" -> new topic and a good description of the problem(s) ... (((maybe a problem on the player unit)))

Your (post-31) "presenting conflicting information":
1) Try to understand the logic "Information-A" and then ... "Information-B" -> which version does make sense ?
2) Start a new topic in pinside.com - we are eager to learn about (our) pins (up to now I have not seen "SCM-2C-L-Pos <-> SCM-2C-M-Pos"). Greetings Rolf

I missed seeing "N" at F-15 5 times!? How embarrassing. I was afraid that was going to happen, but at least now I know to keep looking when the number of switches shown in the Relays table are not all accounted for in the schematic drawing. Thanks Rolf!

And thanks too for the tips on posting etiquette in your follow-up post (#35). I'll work more on the machine this week, and post on the scoring issues if I can't fix them.

PM

that is a rare typo on the schematic. Motor 2C is the only dog bone that should be in the 'L' position. True for all Gottlieb EMs I believe.

Yes.

Hi
I made a JPG for to show "Player-1 / Ball-1 makes 10 Points hitting a simple Stand-up-Target" on the playfield. I have taken parts of the Williams "Fun Fest" schema (look it up in ipdb.org) - which wire is connected to "Powerside of transformer" / which wire is connected to "Return-side of Transformer" - it does not matter.
It is an example of "You must think the factor "Time" into the machine - current starts flowing -> magnetism -> Coils / anchor-plates are moving -> switches are closed (or opened) -> -> ->
You only have a static glimpse - the schema (Game started for one Player, Pin has reset and given the first ball ready to play - AND THEN the 110 VAC-Line-Cord is pulled).

The ball rolls into the Stand-up-Switch-"A" -> "A" closes -> current (green colored line) can flow -> the "10-Point Relay "B"" gets current and start to pull -> by that the relay closes its "Self-Hold-Switch "C"" -> NOW the relay gets current through "green colored line" AND "yellow colored line". Lets say the ball rolls away from the stand-up-switch -> "D" opens -> the 10-Point-Relay now has (only) current through the yellow-colored-line (all this is shown in schema-section-19-20).

The "10-Point-Relay "B"" also closes a switch "E" (schema-section-8-9) -> current (also a yellow line) can flow through the player unit to the "Coil on 10-Point Drum Unit of Player-1 "F") -> "F" starts pulling -> the plunger on the 10-Point-Drum-Unit travels and "at end of travel" opens a switch "G" -> the 10-Point-Relay "H" looses current and let go -> switch "J" opens (((definitely no more current to the 10-Point Relay))), also switch "K" opens -> the coil "L" on the Drum-Unit also looses current -> and let loose -> the spring pulls the Drum-Unit-Coil backward -> the Drum is turned one step = 10 Points are (finally) given.

A beautyful example of "working hand in hand" (10-Point-Relay and 10-Point-Drum-Unit) - caused by "ball hits the stand-up target.
Greetings Rolf

P.S.: Want (?) to figure out what symptoms your pin shows if
AA-A: The stand-up Switch "A" is "faulty always closed" (You put new rubbers on and have accidentally bent a blade on that switch) ?
CC-A: The switch "C" is "faulty always closed" (Your screwdriver has fallen into the pin - onto the switch-stack and has bent a blade on that switch) ?
CC-B: The switch "C" is "faulty always open" (your screwdriver ...) ?
KK-A and KK-B: same questions with switch "K" ?
GG-A: At the "End of Travel" the plunger does not open switch "G" ? (because of vibrations in the Drum-Unit the screws for mounting Switch "G" come loose and Switch "G" is no longer in proper place) ?

a-Wms-Fun-Fest-Example.jpg

Me?
If the harness is easily removable such as when redoing the coin door, I'll remove the harness and soak it overnight in a Tide solution. I try to keep the coils dry. Then the next day I put the harness in water and scrub with a toothbrush and let dry.

If the harness is not easily removable then I first vacuum with a brush attachment to get the superficial stuff. Then I dry brush with a toothbrush to loosen more then vacuum again.

Then lastly I tear a 6" square of an old cotton towel and dip in clean clear water and wring it damp. I scrub wires toward their solder joints not away. I don't use soap in the water because I don't want residue in the harness (soap attracts dirt)
I scrub it into all the areas of the harness, turning the cloth and keeping it clean. The water ends up real nasty and the harness real clean.
Lots of work but looks great.

I'll have to try that. It's difficult to find and trace wire colors as it is now.

Thanks Steve,
Bruce

What are "6A" and "5A" on the Relays list? They're not on the score motor. (only has numbers 1-4)

Bruce

Relays.jpg

The notation in that column describes the relay. That means 6 normally open contacts (switches) and 5 normally open contacts. The 1B means 1 normally closed contact is also present.

Thanks for the explanation.
That means the letter A is normally open and B is normally closed?
C is make make?
How about "2 Disc"?

Bruce

2 disc indicates a relay with the small wiper discs that you find on AS relays -- used for things like match-number generation.

A=normally open; B=normally closed; C=make/break.

The number is the quantity and the letter is the type.

Thanks guys.

Bruce

This is a great topic and I think everyone has learned something new. Thanks!

Hi pinsiders
the topic is "marked as solved" - but there a plenty of questions on "Reading Gottlieb Schematics".
My post here is caused by a problem discussed in a german forum - a Gtb Sheriff (Oct.-1971) did not do the "Control-Bank Reset". The cause was a bent blade (not closing) on the SB-Armature-Switch.

Anyway - will a english-speaking Gtb-Crack please volunteer and make a good description - here or in: http://user.xmission.com/~daina/tips/pub/emTips.html - in detail, step after step: "What happens - in detail - when turning-on the Main-110VAC-Power-Switch in the morning and pushing the Replay-Button" ? -> (QQQ***)

I have an (not yet running) Orbit (Dec.-1971) - it also has that (strange) "SB-Control-Bank-Reset-Relay". "daina" has a description on "Flying Carpet March-1972: http://user.xmission.com/~daina/tips/pub/tip0450.html (Text 4. and 5. and 6. - the SB-Relay ...)

I show snippets of schema "Orbit". Thinking about the "Sheriff problem" I came to the question: "Why is the "Make and Brake Switch on ZB-First-Ball-Relay" drawn as is (and not the other way)". The answer is: "The schema shows: One-Player-Game has started, Reset has been done, Ball is in the Shooter-Lane, 110VAC-Line-Cord unplugged / pulled - the player has not yet made points, so the ZB-Relay (in the Relay-Bank) has not yet fallen (- we could start a game for the next player).

Then the question QQQ*** came. IS MY "answer" RIGHT ? , please tell me - :
The day before - the game has ended regular, in the Relay-Bank the "ZB-First-Ball-Relay" and the "SB-Control-Bank-Relay" have fallen. The player turned-off the 110VAC-Switch.
Next Morning - turn-on the Main-110VAC-Switch causes the Score-Motor to make a turn (through the closed Switch-on-SB-Relay) -> the Control-Bank is resetted through Score-Motor-2C.
And now the player pushes the Replay-Button -> S-Start-Relay gets active -> through Score-Motor-Switch-3B and the (yesterday beeing fallen) Switch-on First-Ball-Relay -> Sb-Relay pulls and falls (at this time NO Control-Bank-Reset) -> -> -> the player plays a game.
The start of the (second play of the day) next play is slightly different: Replay-button -> S-Start-Relay -> Score-Motor turns -> SCM-2C (is earlier) -> Control-Bank is resetted -> SCM-Switch-3B (closes afterwards) -> SB-Relay pulls and falls -> -> -> the player plays the next game - and so on.

Final question: Is this tricky thing (SB-Relay and the SB-Armature-Switch / resetting the Control-Bank / timing) the reason for the tip (I once read): "If You have problems starting a Gottlieb pin - BEFORE pushing the Replay-Button: Manually reset the Control-Bank" ? (And - Is this tip only good for Gtbs WITH Control-Bank AND SB-Relay ?)

Please volunteer and explain in detail ... Greetings Rolf

Gtb-Orbit-SB-and-SB-Armature.jpg

This is going to be a lot of typing...

- turn on the power switch; this activates the transformer, which then makes the 25V and 6V sides active.

- the Hold relay (R) is not yet active from the previous power off, so a closed switch on R will complete a path through a switch on an un-tripped ZB to energize ZB and trip it (if for some reason ZB was not left tripped from a previous game; normally it would already be tripped, but the power on logic will force it, just in case).

- ZB having now tripped partially completes the path to SB, but SB hasn't tripped yet.

- the next thing that needs to happen is to energize the Start relay (S), which isn't shown on the snippet. If there are credits on the game, then this can be done by pressing the replay button on the coin door.

- S energizes. which closes a few switches on S and causes several things to happen:
- a switch closing on S will complete the path to R, allowing R to energize and take over the hold duties;
- a switch closing on S causes the score motor to run;
- a switch at motor 2C closing will complete a path through a switch on S and the preceding tripped ZB to energize and trip SB;
- tripping SB will close the SB armature switch;
- tripping SB will close an SB switch that completes a path to the Tilt Hold relay (H), and H energizing will close a switch on H that will allow the lights to come on;

- S stays locked on until motor 2B opens, but SB being tripped keeps the score motor running (to allow the score reels to reset)

- once the reset completes, the Player Unit will reach a final spot where P5A is closed, then when motor 4C closes, the path to reset the Control Bank completes via the SB armature switch and the Control Bank resets. Now SB and ZB are both un-tripped again.

- a second player can be added until first points are scored.

- when first points are scored, then yet another path to energize and trip ZB is made (through some or all of the points relays). At this point the game is ready to play.

Note that not all of this circuitry is shown in the snippet above.

Also note that in the snippet above, it's not motor 2C for resetting the Control Bank, but more likely is 4C, where the ink has rubbed off the '4'.

Also note that SB only trips to perform the reset duties, and then gets reset with the Control Bank reset. So ZB and SB are not tripped at a power on.

Manually resetting the Control Bank is helpful to ensure that all the relays are in the correct starting state. The game will trip ZB on power on if needed.

This sequence only applies to late 60's/early 70's era games, as Gottlieb kept refining the sequence. Eventually the Control Bank goes away, and is replaced with interlock relays (e.g., AX).