(Topic ID: 258270)

Fixing Gottlieb games that the score motor runs

By tomdrum

3 months ago

Topic Stats

  • 11 posts
  • 8 Pinsiders participating
  • Latest reply 3 months ago by jrpinball
  • Topic is favorited by 2 Pinsiders


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    #1 3 months ago

    I live in a rural section of Central PA and like many here advertise on CL looking for project games and I also offer repair help if not over my head. Bally SS games are what I know best. I get responses now and then to buy games but lately I've gotten multiple requests to fix Gottlieb EM games with score motors running. I've owned a bunch but I'm not an expert with them. I've flipped repair work to Jim at JT Amusements since he's an expert and I am not and he travels here now and then.

    In the last month, I got a call on a Super Score which the owner doesn't want to invest in the repair time so I listed it here for him. Next was a Buccaneer which was HUO for 40 years. Score motor running. Looked at it to buy and probably will. Score reels not resetting so I assume they're gummed up or something else. Tonight a Mibs same problem. Score reels reset and credit comes off when started. An hour later and guy called with a Pioneer same problem. Weird. That's more calls then the last 3 years combined.

    Having studied multiple repair books I have and looked at everything I could find online, never saw a flow chart type diagnostic for this issue. I realize the start up sequence evolved over the years with Gottlieb Em's and I can do the basic stuff like cleaning switch contacts and so forth. I can follow the schematics some what but the jumper wire tests are never laid out in order. Am I missing a repair source (besides posting here, rather learn by doing)?

    #2 3 months ago

    I don't know that I've ever run across a flow chart for diagnosing an EM game. That's more of a software technique so maybe it only applies to SS games that do most of their math in software.

    Score motors from any manufacturer generally have a number of switches wired in parallel that when closed will cause the motor to run. The first step is to identify which of those switches is closed when the motor won't stop running. Once you've found a closed switch figure out if it's closed because it's bent, shorted or because the relay or other device that activates it is stuck on. If the switch is closed because some other device is active and closing it then you need to start over and figure out why that device is active.

    There are lots and lots of topics here that talk about running score motors. That is an often overlooked resource.


    #3 3 months ago

    Some quick tips:

    You can often eliminate some potential switches to check in the score motor circuit based on whether there is scoring while the score motor runs on. If not, then the problem is probably not a scoring relay (such as the 50- or 500-point relay) that is stuck on. If you turn the machine off, then turn it on, manually push in a relay that starts the score motor (such as the 500-point relay) and the score motor moves to its home position and stops, then the home position switch on the score motor (usually on the 1C score motor switch stack) isn’t the problem. Using clues like this based on what’s happening can help to more quickly pinpoint the problem. And when you can’t quickly tell what’s going on, you can also sometimes save time by first checking the switches in the tricky AX relay if it has one. That relay can often be the culprit.

    As for the startup sequence, it is described for each Gottlieb pin in its manual. Gottlieb started making separate manuals for its pins starting with Snow Derby/Snow Queen in 1970.

    #4 3 months ago

    If the game has been sitting for a long time, it's very often a coin switch stuck closed, or a score reel zero position switch open or dirty.

    #5 3 months ago
    Quoted from MarkG:

    There are lots and lots of topics here that talk about running score motors. That is an often overlooked resource.

    Agreed. I've looked at years of those postings and they have good info. But every score motor issue seemed to have a different cause / remedy but the info was informative.

    #8 3 months ago

    Read that top to bottom. I guess I'm wishing there was a better guide to point me the right direction. If score reels reset, then check this. If a credit comes off when starting the game go to this. If score motor home switch is adjusted properly, check this. If you manually reset the (insert name) relay the game will start normally, check this. Guess my Bally solid state mindset which is used to finding the 5V 1st, moving from there to the rest of the required voltages to start, has me mind screwed on these. Diagnostics on these seems to be a crapshoot.

    #9 3 months ago

    Opinions vary.

    #10 3 months ago

    When a score motor keeps running you would first ask the following questions:

    Are the score reels completely resetting?
    Are any of the coin switches stuck in the closed position?
    Are the stepper units completely resetting?

    Problems with these items would include mechanical issues (sticky disc, worn or broken parts) or a problem with the circuit that sends power to the reset solenoid... If these items were working, then you would move to the schematic that showed the circuit that included the score motor.

    (The following assumes that someone has a basic understanding of how to "read" an EM schematic and how electricity flows through EM pinball circuitry.)

    Then you would ask the next question: "What switches are sending power to the score motor?"

    Gottlieb EM machines have a group of switches that I call "primary switches." These primary switches are the only way power can be sent to the score motor. Let's look at a popular Gottlieb EM machine from 1976 called Royal Flush. This machine has ten primary switches that can send power to the score motor:

    C, D, E, G, O, P, S, W, AX, 1C

    So, whenever you have a constantly running score motor, you would want to examine if these switches were clean and adjusted properly. Also, you would check the switch stacks for possible shorts. If everything looked good, then you would want to observe what switches were actually closed when the score motor was running.

    Let's say the E switch was closed when the score motor was running. Then we would look at the "second group" of circuits and switches that sends power to the E relay coil. There are seven switches that are in the circuits that send power to the E relay coil:

    Bounce switch - needs to be closed to supply power to the circuits / not applicable
    Anti-cheat switch - needs to be closed to supply power to the circuits / not applicable
    Score motor switch 2B - might be mis-adjusted and stuck in the closed position
    E relay switch - lock on switch / activated when power reaches the E relay coil /might be mis-adjusted and stuck in the closed position
    Score motor switch 1C - might be mis-adjusted and stuck in the closed position
    Ball return switch - might be mis-adjusted and stuck in the closed position
    A relay switch - might be mis-adjusted and stuck in the closed position

    If everything looked good with the second group of switches, but you saw A relay switch was closed, which is a normally open (NO) switch, then you would look at the "third group" of circuits and switches that send power to the A relay coil.

    As you work your way through the different groups of circuits and switches - primary switches, second group, third group, fourth group, etc - it gets less likely that the problem is a result of switches in the third group or proceeding groups since it would be less likely that multiple switches would have problems at the same time. From my experience, when you have a constantly running score motor, the problem is with the primary switches or second group switches.

    If available, the game operation sequence or theory of operation can be helpful in finding the problem. Other clues can be seen on the backglass or card tray apron - Is the game over light on or off? - Is the match light on or off? - Is a ball in play light on or off?

    Using the schematic and examining the primary switches is the key to solving a problem with a constantly running score motor.

    #11 3 months ago
    Quoted from woody76:

    Gottlieb em are a pain

    They're well made, but a lot of times the way they went about things engineering-wise makes me wonder. They're not terribly serviceman friendly.

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