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Complete Judge Dredd planet disc not turning. Faulty gearbox repair.

paddythegreek

paddythegreek

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EFB1F4CD-87D5-4375-AF9A-C3EDF355CA96.jpg DB7961C6-ADC7-4F54-98DB-59657F7CDF61.jpg Having been asked by a mate to look into why his planet assy wasn't turning i assumed a gear had stripped. So i asked on the group and BigIan posted a link re pinside forum. Helpful but not documented enough in my opinion so hence this log.
Firstly you need to remove the complete motor/gearbox assy from the machine.
Remove the planet plastic assy and then remove the black masking tape from around the globe. Inside is the circuit board that contains the 2 gi and 1 flasher bulb(s). Go under the playfield and on a spindle at the bottom of the g/box is a collar with a split pin through it,remove the pin as it makes it easier to pull the wires up. These wires feed the gi/flasher board that sits inside the globe. Carefully pull the lamp board up (i think you have to remove the bulbs) so you can see where the wires are soldered to the board. Mark the wires and desolder them, remove the board and unscrew the metal plate the lamp board fixes to. Then remove the nut that holds the bottom of the globe in place and remove the globe. Next carefully remove the nut that holds the bracket that the planet plastic fixes to and remove the bracket.
Back to under the playfield. Pull the 4 wires you desoldered earlier down and the inner metal tube away from the assy.
The wires should be still inside the inner tube of the assy. Undo the remaining screws that fix the assy to the underside of the p/field.
You should have something like in the pics.
 
IMG_0541.JPG IMG_0542.JPG IMG_0543.JPG Next step is to remove the bracket that mounts the unit to the p/field. Then remove the motor and bottom inner spindle support bracket.
 
Undo the 2 grubscrews on the bottom collar and do the same to the 2 grubscrews on the top collar. Note the top collar is attached to a brass gear.
 
Note both rivets are still in place. These have got to be removed to split the box.
This is what i used to knock both rivets out as i'm hoping to reuse them.
It's a 3mm masonary naii ground down to a slight taper. The rivets are 1/8" so 3mm is smaller.
Job done and the rivets knocked out easily.
 

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Rivets removed and g/box split
 

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IMG_0550.JPG IMG_0551.JPG IMG_0552.JPG IMG_0553.JPG IMG_0550.JPG As you can see from the pic the 2 brass gears on a short shaft. These need to be removed but wont come out as the gear on the tube shaft is stopping them.
Having earlier loosened the grubscrews on the upper gear collar you need to knock the shaft downwards to enable the 2 brass gears to be removed.
Then remove the gears.
The large gear of the two is the fault. It's spinning on the shaft
 
Good work. I had similar difficulties with the entry wheel motor on works' Popeyes. New motors were fitted since the games were totally out of action, but I split the broken ones to make a good spare by mixing the parts. One had failed like this, with the output shaft loose from its gear wheel, the other had stripped teeth on the input gear/motor. I'd guessed about the former (I think the wheel could be turned manually), and had seen the latter, so I thought there was one good unit between the two
 
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This is a great thread, lots of pictures and descriptions, I have a JD and am always weary of the gearbox, looking forward to seeing the final outcome
 
IMG_0560.JPG IMG_0561.JPG IMG_0562.JPG IMG_0563.JPG IMG_0564.JPG So this morning with some slight trepidation i drilled a hole and inserted one pin before i drilled the other hole. Pics of before and after i cut the pins to size. The gears are back in half the gearbox awaiting new grease. I'm gonna use general purpose grease.
 
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IMG_0565.JPG IMG_0566.JPG Greased all the gears and reassembled the two halves. Getting all the gear shafts to line up was a bit fiddley but using slight hand pressure and a bit of jiggling it popped into place. Then slide the upper collar down the shaft and tighten the two grubscrews. I removed one screw so i could see the original grubscrew marks on the shaft. Repeat the process for the lower collar
 
IMG_0568.JPG IMG_0569.JPG IMG_0570.JPG Because i'd knocked out the rivets using my home made tapered tool it left a hollow in the end of the rivets. I carefully knocked the rivets back into place and rested the good end of the rivet on a small rod the same size as the rivet head
Using a centre punch in the hollow i tapped the punch causing the hollow to spread and hold the two halves together.
The bottom inner rod bracket went on next followed by the main mounting bracket assy.
All done and ready to be installed back into the m/c but i did power it up one last time for my peace of mind. Yep it still works.
 
To be honest if the guy on pinside had put more info on i may not have done a log, but as it seemed there was a lot of info missing i thought it's gotta be worth it. If it helps a few people save money by following this and doing what i'm doing then it's a result.
 
IMG_0572.JPG IMG_0573.JPG Hopefully the final furlong this morning.
The shaft i am holding with the wires running through pushes inside the tube. There is a thread on the top end of this shaft that the plate for holding the gi/flash bulbs secures to. Note the hole through the bottom end of the shaft. This shaft does not turn and is eventually secured to the bottom bracket of the gearbox assy.
So push it inside the tube (i oiled it slightly. Ok it don't turn but the tube it fits into does) further than it's final locating position. You need the wires long for ease of soldering to the the gi/flash board
 
Great thread, I respect this attention to detail and innovative repair:clap:

Was wondering how was the gear that came loose originally attached to the shaft?
 
IMG_0574.JPG IMG_0575.JPG IMG_0576.JPG Next fit the planet plastic unit securing it with the nut and star washer. Then fit a nut onto the thread of the globe shaft followed by the lower globe and lock nut and star washer. The round metal plate is next which the gi/flash circuit fastens to. This screws onto the inner shaft that don't rotate. Ok time to solder the wires back onto the board then fit the board onto the plate and secure it with the 2 screws
 
The large gear came loose as the small gear has a small flange each side of it on the shaft. The large gear and one of the flanges are splined but the splines are that shallow i'm surprised the damn things lasted as long as it has. Deffo a design fault imho
 
IMG_0577.JPG IMG_0578.JPG Having fixed the lamp board in position with new bulbs i secured the inner spindle to the bottom assy bracket with the split pin through the holes. Push the wires to one side whilst pushing the split pin through. Power to the gi bulbs only at the moment as i want to double check my work before i power up the motor/gearbox.
 
IMG_0580.JPG So replaced the top of the globe and secured it to the bottom with black insulating tape. Replace the planet disc and secure with the 3 screws. Having checked everything i've done i connect up the plugs i removed to get the unit out. Go into planet test and great. The planet is turning smoothly with no more noise than it had before. I've played a 3 ball game and i'm cheating as i have the glass off but it appears to work exactly as it should
Gotta try and find a way to put a video on.
 
@paddythegreek I'm almost done repairing this same problem (and your guide here has been a huge help!), it's mostly put back together but I've got these two short metal tubes and I have no idea where they fit! any idea?

They fit inside the main tube attached the the gear box, but then the metal spindle that the LEDs sit on just pushes them back out. I can't spot anything in my or your photos, or the manual either.

IMG-7790.JPG
 
Hi this was a long time ago for me but post no 2 has 3 pics. The middle pic shows spacers on the gearbox where the motor attaches.
Post no 14 last pic shows spacers as well. If it's not these then i've no idea as it was a mates machine.
Sorry about this but the spacers look like they sit between the sides of the g/box so it helps the motor sit straight.

Ken
 
Bingo! Spot on, can't believe I missed them in that photo - wood for the trees etc.

I should now be able to finish up the repair the next time I'm at the club where Dredd is right now. Thanks a bunch @paddythegreek
 
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