(Topic ID: 239050)

Strange Black Knight flipper issue (Update: SOLVED, see post #10)

By grinchia

1 year ago

Topic Stats

  • 10 posts
  • 3 Pinsiders participating
  • Latest reply 1 year ago by grinchia
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    #1 1 year ago

    So I have a fairly rough original Black Knight machine bought a few years ago that originally had plenty of issues, many of which I have managed to resolve. I had pretty weak flippers and replaced the mechanical portion (piston/lever arm/spring) of both lower playfield flippers with a newer and more reliable style (the type with the long, narrow tension spring holding the flipper in it's rest position rather than the large conical compression spring). The left side now works fine, but the right side is pathetic. It activates but very weakly, buzzing and struggling all the way. Here's what I can tell you:

    The mechanism moves freely when I manually cycle it from beneath the table with no binding or unusual resistance compared to the good flipper on the other side

    Voltage is about 37 volts at the leaf switch (I have cleaned with paper and get a good spark when I slowly close the switch wit the flipper button)

    When I have the playfield tilted up on the prop rod, the flipper seems to be as quick and snappy as it should be, but as soon as I lower the playfield down again it is once again hopelessly weak. To me it seems like this must be some kind of mechanical binding, but honestly I can't feel any unusual resistance when I cycle it manually. Any suggestions on what I should check next?



    #2 1 year ago

    Use a jumper wire across the end of stroke switch and then press the flipper button. If it works strong you have a bad switch.

    #3 1 year ago

    Thank you mikat11, I will go and check that now.

    #4 1 year ago

    Just looked. The EOS switch is new and makes good contact (closed when flipper at rest) even when the field is lowered. I put a jumper across just in case and tested it, no improvement. Next thought?

    #5 1 year ago

    Did you replace the bushing that goes through the playfield? If not could be worn weird. If you did it could be installed improperly.

    Did you gap the flipper from the pf properly?

    Look to see if the flipper rubber is binding on the inlane guide.

    Did you change the coil sleeves?

    Check voltage at the coil not the button.

    Check the wiring on the coil to make sure it is correct. Previous owner could have the lugs wrong.

    That’s all I got.

    #6 1 year ago

    Thank you Black Knight. To address your questions:

    Yes, I replaced the playfield bushing.

    Yes, I gapped the flipper from the playfield properly.

    No binding of the rubber on the inlane guide.

    New coil sleeve.

    *I will check the voltage at the coil and see if it differs from the switch

    *There is some obviously molested wiring on the coil, I will check and see if it is correct.

    #7 1 year ago

    So the wiring looks correct, and I get 24 volts at the coil for both the normal left flipper and the droopy right flipper.

    I feel like it ought to be a mechanical rather than an electrical issue, because when I activate the flipper when the playfield is propped up it seems to work fine. That's what really has me puzzled.

    #8 1 year ago

    I'm thinking that there is a wiring issue. Moving the playfield up and down is also moving the bundle of wires going to the playfield. There may be connectors in the bottom of the cabinet from the back box to the playfield. I would trace the wires from the weak flipper to wherever they go and check for damage or a bad connection.

    #9 1 year ago

    When it’s up gravity is helping the flipper so that’s not always a great indicator.

    I can’t remember if the power goes to the upper flipper first or second but if the other one is working right it’s prob not a cabinet connector issue. But I guess there is a connector between the pfs. So need to Check it I guess.

    Are the coil leads good? Maybe you have a broken wire on the coil? Have you check resistance on it?

    If you are really stuck, swap upper and lower assembly and see what changes.

    #10 1 year ago

    Update: SOLVED

    Turns out it was in fact a mechanical issue. Although I had gapped the flipper to spec something came loose and there was too much play between the flipper shaft and the playfield bushing, causing the piston to bind against the coil mounting bracket. I pulled the whole thing out and disassembled/reassembled it, gapped it again, and snugged the retaining nut tighter. Bingo! I can play again!

    Thanks for your input everyone, sorry for being a noob. I'm learning : )

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