(Topic ID: 251960)

"A" Relay Contacts: Open or Closed

By redrock

8 months ago

Topic Stats

  • 12 posts
  • 3 Pinsiders participating
  • Latest reply 7 months ago by redrock
  • Topic is favorited by 1 Pinsider


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    King Pin Ball Count Zero Position switch (resized).jpg
    King Pin A relay (resized).jpg
    IMG_4416_cr (resized).jpg

    #1 8 months ago

    I asked my question in one of my old threads about my Gottlieb King Pin 1973 EM but thought it would be better to start a new open; I hope this is OK.
    The start-up sequence is not working; I believe because of this relay.
    The schematic shows the 4 score reels to be open without power but the way the contacts are set, when the relay engages the long contract pulls away so all four can't close but open. This suggests that they are N/C and then open which is opposite the start-up sequence. Something is wrong but I cannot see it.
    Any help would be appreciated to get past this.

    IMG_4416_cr (resized).jpg
    #2 8 months ago

    I'm not totally following you and I do not own the game or the schematic.

    But, bear in mind that the (GTB) schematic is drawn to show the state where the game has fully reset, ball is in shooter lane and game is unplugged. Normally that lack of power means relays are no longer "pulled in" and the drawn state of the switches reflects that. But you show a latching relay which can remain "pulled in" even after power is removed, due to the adjacent relay coil's armature latching it in the pulled-in state. So the schematic for these latching relays may appear backwards at first glance.

    #3 8 months ago

    Thank you for your post and insight; I'm at my wits end. This is what the startup sequence says regarding the "A" relays:

    ..."'A' relay coil is actuated by the switch on motor 2C".
    ..."When 'A' is actuated, it is locked in by the armature of 'A' relay reset coil". Through closed switches on the score units reset to zero through a switch on motor 1A. When all units are reset and motor 2B makes, 'A' relay reset coil is actuated. This release the armature on 'A' relay and opens the switches."

    So, with power off the switches are closed and they open for just one cycle as the reset armature latches. The will stay open until all the score reels are zero and then the reset relay will return the four switches to the closed positions.

    I'm thinking that maybe the issue is the motor stops and doesn't continue as it should until all reels are zero. Maybe motor 2B is making too soon? I'm going to check this out.

    #4 8 months ago
    Quoted from redrock:

    The start-up sequence is not working;

    Can you elaborate?

    Here are the relevant bits of the schematic:
    King Pin A relay (resized).jpg
    The relay table shows that the A/Reset Completed relay is an interlock relay with 6 switches (5A, 1B). Five are normally open (5A) and one is normally closed (1B). As jeffc mentioned the state of the switches on the schematic can be confusing since the relay holds its position when the game is unplugged, but as long as you have 5 switches of one type and 1 of the other and they're actuating appropriately your relay is probably fine.

    Quoted from redrock:

    I'm thinking that maybe the issue is the motor stops and doesn't continue as it should until all reels are zero. Maybe motor 2B is making too soon?

    The A relay is one of several that can make the Score Motor run so it seems more likely that the A relay is releasing prematurely rather than the Score Motor is stopping too soon. Once activated by the S/Start relay and the motor 2C switch, the A relay should remain tripped until the A Reset relay fires when all the score reels reach zero and the motor 2B switch closes (at the very end of the Score Motor cycle).

    If your score reels aren't resetting all the way I'd suspect that one or more of the score reel zero position switches aren't opening appropriately.


    #5 8 months ago

    Thank you Mark, I think one of my issues is that the playfield is up on its support and I've jumpered both the Hole and Trough switches in different combinations. What is the correct state of these two switches as I troubleshoot the start-up sequence?

    #6 8 months ago

    Those switches should only come into play at the very end of the reset sequence when the game is ready to serve up the ball and add to the ball count. I think the game should be able to complete the rest of the reset sequence with those switches open.

    But I'm still not clear, what specifically isn't working?

    #7 8 months ago

    The problem is getting the score reels to zero, to complete the start-up sequence.

    Sometimes I put this aside and work on the other switches and the scoring. To do this, after the start-up is complete (other than the score all zeros), I HAVE to press the hole switch AND the trough switch. Then I can work on the other things. If both of these are not depress, nothing works.

    So, maybe once the zero reset is fixed, everything will fall into place. I have been thinking what you said about the NO switches. They close for one cycle of the motor; I just have to figure out why the motor doesn't stay on until the zero reset is complete. (It's ironic that most people with motor issues stay it will not stop!)

    #8 8 months ago

    What is your A-reset relay doing? Anything strange mechanically (slipping?)

    As markg says, S pulls in which starts the motor. During this motor cycle, motor switch 2C will pulse to actuate 4 things: play meter, subtract replay unit, reset ball count unit and the A relay.

    I'm assuming you can observe the A relay activate.

    Now that A has pulled in, it should not let the motor stop until A-reset fires to unlatch A. And it could take a few motor cycles because some reels will have to increment from 1 all the way around to 0. A-reset can only fire when all four score reels' reset switches are closed.

    If you set your reels to 1111, what do they show when the motor stops early? The same showing each time?

    Could *ALL 4* score reels' reset switches be closing too early (adjusted wrong)?

    There is no lock-in circuit that could prematurely open to lose your A relay (which is powering the motor) so if you are getting different scores after each reset attempt from 1111, I'd suspect the closed switch on A that powers the motor might be dirty or lacking enough bias to keep it closed.

    Note: I'm working off of a 74 1p Sky Jump schematic.

    #9 8 months ago

    I suppose that if the motor is stopping prematurely due to poor NC switch on A relay, then the A-reset would never fire and A relay would remain latched.

    Also, if your score reels are only getting to 4's or 5's it could be that the A relay is not powering the motor at all and you are only seeing the last few 1A motor pulses to the score reels while the S relay finishes up its time with the motor.

    #10 8 months ago
    Quoted from redrock:

    I HAVE to press the hole switch AND the trough switch. Then I can work on the other things. If both of these are not depress, nothing works.

    There's a switch on the Ball Count Unit that cuts power to most of the playing and scoring parts of the game:
    King Pin Ball Count Zero Position switch (resized).jpg
    It's common on many Gottlieb games. What happens is that after resetting the score reels and all the game features, the ball in the out hole fires the O/Ball Return relay which in turn kicks the ball through the trough to the shooter lane. On the way, the ball closes the Trough switch which steps the Ball Count unit out of the Zero position which closes the switch above and provides power to most of the rest of the game.

    When debugging with the playfield up you can usually let the game reset, then tap on the Trough switch from underneath the playfield to advance the Ball Count unit and power the game.

    #11 8 months ago

    Thanks for the help. I'm going to spend some time going over things and take good notes; stay tuned.

    3 weeks later
    #12 7 months ago

    Life intervened, and now that I have gotten this out of the way, back to my fun. I think that my problem is one that I have had from day one, i.e., the "A" relay.

    The motor switch is normally closed, so the motor will run. But, when "A" activates, the blade pulls away and the switch opens, stopping at one cycle and not allowing the reels to continue until reset. Taking my finger to close it causes the motor to run. When all the score reels go to zero (reset), the "A" Reset relay activates, the "A" opens and the start sequence is complete. The three other operations for start up all work for the one cycle, while the reels requires more than one cycle, hence the problem of the motor stopping at one cycle.

    The "A" motor control is just backwards; it seems possible that it could have be reconfigured but I can't imagine how this could happen. I know that I am missing something; I need some help.

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