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MMRLE VUK/Coil issue?

Discussion in 'Pinball Tech Support' started by Golden Graham, Sep 15, 2020.

  1. Golden Graham

    Golden Graham Active Member

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    Haven't posted in a while...in fact, haven't even turned my machine on in a while! I did today, it has roughly only 350 plays on it.
    During my first game, my ball went into the moat trough and the VUK wouldn't kick it up. When the machine attempted to look for the ball, that coil wouldn't fire when all others would? Cannot figure out why? Everything is pristine and rarely even used. Any ideas as what I might be looking at; and perhaps some steps to solve it? All connectors are seated properly (pretty sure they are on the blue board above the moat).

    Thanks
    Kyle
     
    #1
  2. Mike Gratton

    Mike Gratton Member

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    Check that the coil has both wires still attached.

    Re-seating the connectors is usually the first step (after you confirm the wires are still soldered to the coil). You may need to put foam or other material under the large board to prevent it from flexing as you re-connect the connectors.
     
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  3. Golden Graham

    Golden Graham Active Member

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    All wires are perfect. Board has perfect seating. I am confused!
     
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  4. Mike Gratton

    Mike Gratton Member

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    Did you physically re-seat the connectors or did you just look at them? It's a known issue. Remove connector and re-connect.
     
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  5. Golden Graham

    Golden Graham Active Member

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    Physically re-seated. But I will do it again.
     
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  6. Golden Graham

    Golden Graham Active Member

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    I think I found the problem...it was a total NOOB problem. I had a blown F1 Fuse (4A) on the blue circuit board. I haven't replaced it yet as I don't have any, but I guarantee that is the problem.
    Thanks for the suggestions though!!

    Kyle
     
    #6
  7. sylvain

    sylvain Active Member

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    Can we assume that F1 is a slow-blow fuse? Probably is my guess.
    The other question is why that fuse blew in the first place.

    If it blows again after replacement with a proper-rated fuse, then it could be the
    drive (transistor/snubbing diode across the coil which might be located on a board).

    Good luck!
    -Sylvain.
     
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  8. Golden Graham

    Golden Graham Active Member

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    Sylvain, It blew again right away.

    What should I be looking at? I don't really understand...
     
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  9. sylvain

    sylvain Active Member

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    Looks like there is a short to that line, or most likely the associated drive transistor (to this specific VUK coil) is shorted on the driver board.
    You will need the game manual and a Digital multimeter to identify the bad part(s) first, then obtain a proper replacement, and replace it.
    Soldering will be involved. Hopefully those are not surface-mount components. You might need to hire a good experienced tech if this is still cryptic/unclear to you. Note that there are quite a few web sites out there on how to test drive transistors, etc.

    Alternatively, perhaps this new game is still under some kind of warrantee and/or the manufacturer might offer free tech servicing over the phone or email? Or a replacement board? Something to check before starting troubleshooting...

    Best of luck!

    Regards,
    -Sylvain.
     
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  10. Golden Graham

    Golden Graham Active Member

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    Thanks for the input.
    I am sure there is no warranty, but I contacted Chicago Gaming anyway. I don't mind buying a new board as I truly suck at fixing boards. I have the game manual, but I really don't know how to read the schematics. So weird how this happens when the game has literally been off for months. I was going to take pics to sell it and decided to play a game...of course something had to go wrong! lol.
     
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  11. Golden Graham

    Golden Graham Active Member

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    So I replaced the solenoid driver board and the fuse didn’t blow until I played a game (so it wasn’t the board...waste of $115).
    Upon further inspection I found that the fuse blew when the castle was destroyed and the tower spires shook and did their thing.
    So I looked under the game again and noticed that the coil that controls the movement of the castle was “burned”:

    can a burned/fried coil cause a fuse to blow?

    Thanks for the help

    Kyle
     

    Attached Files:

    #11
  12. Mike Gratton

    Mike Gratton Member

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    yes!
     
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  13. Golden Graham

    Golden Graham Active Member

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    so that causes a fuse to blow? Why would a coil burn out?
    Is there a place in Canada that sells coils to avoid the border?
     
    #13
  14. sylvain

    sylvain Active Member

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    Given the fact that the fuse did not blow immediately at power-up with the new board, but did with the old board, proves that the old driver board definitely has a shorted drive transistor on that circuit to that coil. So you did not waste your money on that board, at least initially.

    Unfortunately you have a 2nd issue of that burned coil. That will blow the fuse once its drive transistor is activated. Chances are that the new board now has its drive transistor busted as well, due to the burned coil :(. Hopefully you are lucky and the transistor survived the ordeal this time.

    ... A burned coil would often overheat/short its associated drive transistor, and vice-versa, a shorted drive transistor would burn its associated coil if overfused.

    Most pinball coils (except for flippers) are designed to operate only for a short time.
    If locked-up due to a shorted drive transistor for instance, the current drawn is high, cause the coil to overheat, and will cause the destruction of the coil and/or drive transistor if a fuse does not protect/open quickly enough (such as being overfused).

    -Sylvain.
     
    #14
    Last edited: Oct 12, 2020
  15. Golden Graham

    Golden Graham Active Member

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    Thanks Sylvain

    I have my old driver board in front of me with my DMM.

    how do I test the drive transistor? Where do I put the black and red prongs and what should the DMM be set too?
    9C3A6B52-7D67-43A6-91FA-39DFE069505B.jpeg
     
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  16. sylvain

    sylvain Active Member

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    What is the number on these transistors?
    I cannot see on the pic...

    Also, if you have the game manual and schematics, locate the castle coil that is burned in your game, and follow the schematics diagram to identify which transistor drives it.
     
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  17. Golden Graham

    Golden Graham Active Member

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    On the transistors it says: (the black tabs with the three prongs)

    F3710Z
    1R. 747P
    B6 V6

    I have the manual....schematics are not easy for me to read...lol
     
    #17
  18. Golden Graham

    Golden Graham Active Member

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    Maybe this? image.jpg
     
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  19. sylvain

    sylvain Active Member

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    F3710Z is a MOSFET high-power drive transistor.
    Looking from the top of the board, left to right, the pinout of each of those drive transistor is:

    gate drain source

    Start with your old original driver board.
    You should be able to put your DMM in ohm or continuity/beeper test.
    Chances are that the bad drive transistor on that board has its drain-source pins shorted internally.

    Put any of the two DMM probes on the middle drain pin of one transistor, and the other DMM probe on the right source pin of the same transistor.
    Check each transistor one at a time until you find the one that shows a short between those two pins.

    Incidentally there are amazing web sites out there describing in details how to test drive transistors in pinball machines, including on youtube. Feel free to Google if my explanation is not quite clear enough.

    Looking at the schematics extract you posted above: We are missing one piece of info.
    Which connector does that burned castle coil connects to, on that driver board?

    Good luck!
    -Sylvain.
     
    #19
    Last edited: Oct 12, 2020
  20. Golden Graham

    Golden Graham Active Member

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    Ok Sylvain.

    put the DMM on beep.
    The only transistor that made a beep was the one second from the right/fuses.
    All others faintly illuminated the green LEDS above the fuses. Does the beep mean that that transistor is bad?
     
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