(Topic ID: 251326)

Need Gottlieb Grand Slam continuous stepper unit help.

By jetmechinnc

2 years ago

Topic Stats

  • 9 posts
  • 3 Pinsiders participating
  • Latest reply 5 months ago by Tlw7409
  • Topic is favorited by 1 Pinsider


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#1 2 years ago

Please, I need help getting to home plate!

I have been going through and restoring my Gottlieb Grand Slam. After I cleaned the stepper unit by the chime box. I cannot seem to figure out what the correct mounting should be of the rotating disc. Is there a zero point on this stepper unit to assemble it correctly? Cant seem to find it anywhere. I can remove the 3 screws and reclock the disc and it will completely change how it scores runs, etc.

Plus, if I manually advance the disc using the coil plunger, the rivets align with the rotating studs. During game play, it only advances it half way between the studs, if I loosen the three screws and align the disc using the adjustment slots, the posts hit the rivets perfectly. Could this be a weak coil? Everything else seems to be working correctly the best I can tell. This simple stepper unit is confusing me, and I was hoping to have this restored and running correctly for my Dads 73 birthday this month!

Thank you in advance.

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#2 2 years ago

The notch on the disk is the home position. it should step step 5 or 6 times between cycles so there should be several cycles on the total revolution. so if there is 5 or 6 steps between notches just line it up with the finger. The finger closes outside the notch and will power the unit until the next notch.

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#3 2 years ago
Quoted from pinhead52:

The notch on the disk is the home position.

So there are several notches on the disc, doesn't matter which one? As far as the game not fully rotating the disc from rivet head to rivet head, compared to manually moving it at the coil/lever arm, would you recommend replacing the coil? Once the disc rotates, you can clock the disc forward or aft to align the rivet rows with the adjustment slots, should they be aligned to the forward row or aft row? Once the switch drops into the notch, should the disc be adjusted then?

Sorry for so many questions, this last thing just frustrates me. Total reset stepper units at least makes sense to me, there is a start and a finish point.

#4 2 years ago

yes, once the notch is lined up with the switch it is roughly aligned. with power off you manually step the unit to a rivet, ie 1 step and then eyeball how the shoe(s) is aligned with rivet, making any "fine" adjustments.

As to the coil, no, clean and gap the notch contact. there may be other contacts like a 1A contact that needs to be cleaned as well.

#5 2 years ago

Ok thank you for the help. I will try this either after work or start on it Monday for sure. I will let you know how it goes. Wasn’t sure if I needed to order new springs as well from Pinball Resource. Again, it manually always works as it should when I moved the plunger, just doesn’t move the disc as much when the game is doing it with electric power.

#6 2 years ago

you probably need to replace the notch contact. Ive seen where pads will become loose in the finger and give flaky results. My quick fix is to take a heavy set of needle nose pliers and mash the two sides of the contact pair into there fingers. Works for a while but if its burnt real bad (scorching on the back side on the finger) you'll need to make up a replacement.

#7 2 years ago

Talked with Steve Young at pinball resource as well, he mentioned checking the 1A contact on the score motor, it may not be giving a long enough pulse for the run stepper unit to actuate correctly causing the stepper unit to not fully rotate like it can when I manually manipulate it. Can't remember if there is a diagram of the unit or not attached to the game to tell me which one is the 1A contact.

I will closely inspect the notch contact as well, didn't really look at it that closely when I had the pallet out. Thank you for the advise!.

#8 2 years ago

Evey gtb game has a 1A contact, its the lowest level and there are 5 hits per 120 degree cycle, ie thars what scores your 50 points

2 years later
#9 5 months ago

I had this same issue. It turned out to be a broken metal stopper that is adjustable in the stepper. Look at all three of these metal stoppers on your runs stepper and make sure when you activate the stepper very fast, and let it release fast (like the real action of a solenoid), it should be advancing correctly. This solved it for me. It sounds like the exact thing you’re experiencing.

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