(Topic ID: 246168)

Gottlieb score motor stops just short of normal stop - PROBLEM SOLVED

By valveamp

11 months ago

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  • 16 posts
  • 6 Pinsiders participating
  • Latest reply 3 months ago by JudeRussell
  • Topic is favorited by 2 Pinsiders


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Motor4 (resized).jpg
Motor3 (resized).jpg
Motor2 (resized).jpg
Motor1 (resized).jpg
0King-of-Diamonds-Work-14 (resized).jpg
KoD Score Motor broken wire (resized).jpg
King of Diamonds Score Motor 1C (resized).jpg
King of Diamonds switch dogs (resized).jpg
Gottlieb KoD score motor bad position (resized).jpg
Gottlieb KoD score motor good position (resized).jpg

#1 11 months ago

Hi. I have a Gottlieb King of Diamonds. The game works well, but there is one small problem that has multiple impacts. The score motor stops short of where it is supposed to stop. When this happens, if you just push it to required stop (about a 1/4 to 3/8 of an inch) the game will work fine. The results of stopping just short of the stop is that some of the targets don't score and ring the bell. These are the targets which do not run the score motor, like 1 point targets, for example. The rotation to the correct stop sometimes works and sometimes doesn't. I have not determined if there is some repeatable, consistent way to always make it work. It doesn't seem to be just one stop location every time. I know there are several switches on the game that starts the motor running. I'm not really sure which switch stops the motor. If someone has some insight into where I should look I would really appreciate it.

#2 11 months ago

There are several switches that can start the Score Motor turning, but once the motor is in motion a switch at position 1C closes and should keep the motor running until it reaches the next index position where the Score Motor 1C switch will open, cut power to the motor and make it stop.

The Score Motor 1C switches make up the switch stack that follows the top cam and drops into a gap in that cam when the Score Motor reaches its index or home position.

On King of Diamonds the Score Motor 1C switch connects a red-white wire to a slate-yellow wire. Check to see if that switch is perhaps gapped a little too wide so it opens just a little too soon. If that's not the cause we'll have to look at the switch dog position.


#3 11 months ago

Can you take a picture of the topside of the motor?

#4 11 months ago

Hi. Let me try the suggestion from MarkG first. If that doesn't work, I'll post a photo. Thanks.

#5 11 months ago

I may be looking at the wrong switch, I'm going to double check. What is the switch dog?

#6 11 months ago

Here are 2 photos. The first one is the score motor in the "bad" position. The motor has stopped before the switch "falls" into the cam valley. The second photo is the score motor in the good position. You can see the switch is fully in the cam valley. Maybe someone can indicate which one is 1C. I think switch bank 1 is at the bottom of the photo. From Mark, the red-white wire is on the top of the #1 stack, in this photo orientation. It looks to be closed, but, maybe, it's not really. I have to look at it closer. Maybe I'll try to adjust it a little. Be good to get a confirmation that this is the correct switch. I see what look to be red-white wires on that switch, but there is also another set of wires that could be considered red-white at the bottom of this switch stack (bottom in this photos). However, that switch is fully open, so that motor shouldn't be turning in that case.

Gottlieb KoD score motor bad position (resized).jpgGottlieb KoD score motor good position (resized).jpg
#7 11 months ago

Here's your first photo with some annotations:
King of Diamonds switch dogs (resized).jpg
The switch you're looking for I believe is the innermost switch on the top switch stack in the lower left corner. Note the matching wire colors I mentioned earlier from the schematics. Your motor looks a little grimy (no offense) so it may just be a matter of cleaning that switch. If you slip a piece of paper between the contact points and turn the motor by hand (with the power off) to close the switch, then pull out the paper I bet it comes out with a lot of grime. Repeat that a few times until the paper comes out clean. Don't use contact cleaner. A little mineral spirits would help if you think you need it.

These diagrams from the schematic show some of the Score Motor details:
King of Diamonds Score Motor 1C (resized).jpg
The first diagram shows the switch stacks as seen from the top. You're looking for the #1 stack in the red box.
The next diagram shows the switch levels from the side. You're looking for level C, even with the upper cam.
The third diagram shows an outline of the switch dog. The two slots represent the S and L positions.
The last table shows the switches at each position around the motor. Score Motor 1C switch stack has 1 "A" form switch (normally open) and 2 "B" form switches (normally closed). That's another clue about what switch stack you're looking for. It also shows that the stack should be mounted in the S position of the switch dog.

If you look closely at your annotated photo you can see that your Score Motor 1C switch stack cam follower is mounted correctly in the S or shorter position.

#8 11 months ago

Look towards the end of that thread. I had a score motor timing related issue and i tried a few things before i figured it out. There some helpful information in there i think.


#9 11 months ago

Thanks for the link. I think my problem is different, because, I think, you had a problem where something (a reset) was happening when it shouldn't have happened due to a timing problem. In my case, nothing is happening like that. The problem is the score motor stops early and the switches do not drop into the cam valley as they should. This cause some of the scoring not to work. Any scoring that doesn't go through the timing motor does not work. My timing problem is that the motor stops early, but it doesn't do that in every case. I haven't found a consistent case that always causes the problem to happen or not happen.

Thanks for the photo mark up and explanation. I had forgot what A and B meant relative to switches and I had no clue what "S" and "L" meant. Regarding 1C. I wasn't sure that it was closing all of the way and thought there may be a slight gap. So, I adjusted it slightly just to get a little more pressure on the contacts. Also, I cleaned the contacts not with paper, but with a little contact cleaner paper that I got from Pinball Resources. Unfortunately, neither action fixed the problem

So, here is a question, if the contacts on 1C are actually closed as the motor is moving, and opening up 1C, as the switches move into the cam valley, stops the score motor, what's stopping the score motor early? As best as I can tell, when the motor stops, the 1C contacts are still closed. Doesn't that indicate that there is something else going on that is controlling the power to the score motor? if 1C is closed, how can the motor be stopped?

#10 11 months ago

Problem Solved!
It turns out that the red-white power wire is not directly attached to the 1C switch. It’s directly attached to the 1B switch just below it. As I was playing with the score unit, I saw a flash coming from the back of the 1 switch stack. Upon closer examination, I saw the tiny wire (bare) jumper and it was broken. The interesting thing is that the wire may have been making intermittent contact, but when I moved it off (i.e. no contact), the score unit still worked intermittently, like it had before. I’m guessing that, perhaps, there was enough momentum in the score unit to move the 1C switch into the cam valley, sometimes, but I’m not sure. Also, it appears that switch 1C does not deliver power to the score motor at all times. With the jumper wire off, the score motor still runs. I’m guessing that there is another switch contact that powers the score motor for most of it cycle, but it switches off and relies on 1C to complete the power cycle (???). Anyway, putting in a new jumper from 1B to 1C solved the problem. It now scores reliably. Not sure I would ever found that if I hadn’t seen the arc flash. Thanks to everyone for your help. I learned something about the game and how the score motor switches work. See the attached photo of the broken wire.........

KoD Score Motor broken wire (resized).jpg
#11 11 months ago
Quoted from valveamp:

I’m guessing that there is another switch contact that powers the score motor for most of it cycle, but it switches off and relies on 1C to complete the power cycle (???).

Yes, I believe that is exactly what that switch at 1C does. Other switches can each start the score motor (your schematic should show a number of switches in parallel, each of which will start the score motor), but these generally open before the cycle is complete. The 1C switch makes sure the score motor completes the cycle and stops.

I’m glad you resolved your problem!

#12 11 months ago

Also, here’s a thread by an EM tech explaining circuits and how the score motor is used in them. It’s a good study, and I’ve found it extremely helpful. I want to give a shout out to stevefury for putting it together!


#13 11 months ago

Thanks, Wolverinetuner.
Yes, I saw all of the switches that turn on the score motor on the schematic as you mentioned. I just didn't know how long they stay on. 1C takes over the power control somewhere in the cycle. Also, thanks for the link on the score motor operation. I'll take a look at it.

#14 11 months ago

Hi valveamp
please do me a favor - see the JPG - on my schematics in two places stuff is missing and on a third place I do not know is the switch named "O" or "D" or what (?).
Please make pictures (with Your mobile phone camera (?)), the quality of the pictures is not so important --- so I then can draw my schematics to be complete. Greetings Rolf

0King-of-Diamonds-Work-14 (resized).jpg
7 months later
#16 3 months ago

Chiming in with a little "me too" - nearly identical problem, but with a different solution.... in my case with a #duotron that has been heretofore behaving well.

I recently upgraded the flipper coils (which may be temporary, jury is out, different and unrelated issue) and I suspect while I was poking around must have bumped something.

The game started hitting Game Over mode at the end of random balls - ball would be kicked to the shooter, but Game Over was lit, match number came up, playfield dead.

As I was troubleshooting that, I worked my way to the Motor N/C 1C contact (which I am convinced is pretty much the root of all evil), and I noticed the exact same symptom as @valveamp - the motor would stop prematurely before the cam opened the N/C 1C relay (see photo). That led me to this thread (which did not solve the problem, but got me thinking of different ideas. After monkeying around with 1C for a while (checking contact condition and spacing, manually moving the motor, the contacts, jumping out the contact (motor would run, and not stop), I noticed that if I pulled the entire 1C contact bank away from the cam (no contact between the cam and the lever arm) the motor would run, same as jumpering N/C 1C)

I'm guessing there's a little piece of insulating paper between the contacts and the 1C lever that is not doing its job, because when I slipped a small piece of card stock in there to insulate that set of contacts, the problem went away. Not a permanent fix, but a fix....

Sharing so maybe the next person might figure it out a little quicker than I did....insights welcomed.

Motor1 (resized).jpgMotor2 (resized).jpgMotor3 (resized).jpgMotor4 (resized).jpg
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