Rock Ola 473

Next up is a Rock Ola 473 jukebox with several problems:
1. The coin mechanism does not accept any coins.
2. It’s not possible to enter any credits manually with the coin mech switches.
3. When there are credits in the machine it’s not possible to select a record, nothing happens when the third key is pressed.
4. The gripper does not manage to the return the record to the magazine.

I started with the fourth problem. The gripper mechanism needed to be taken apart, cleaned and greased. The old grease has become more like gum and causes the gripper to be a bit too slow. It didn’t manage to close until the arm had already been lifted from the record and the record remained at the turn table. I found a youtube video showing exactly the same problem: https://www.youtube.com/watch?v=b9zx8y2WU74

Here you can see what the gripper mechanism looked like before I started the rebuild. There are dried grease and oil residue on the outside. The same at the inside, I had to use a knife to get rid of the dried grease at the shaft inside the gripper spider.

Here are the parts after de greasing and cleaning. Before I assembled the gripper again I run the gripper arm and gripper spider in the bead blaster to clean of the oxidation. Once assembled and properly greased the gripper worked as it should again and problem number four could be ticked of the list.

 

 

The gripper is a clever piece of mechanics that performs a complicated sequence using surprisingly few parts. There is probably a lot of thinking and testing invested in the construction and once it was working it was used in the jukebox designs for a lot of years, with just minor changes during the time. The most common problem with the gripper is that it is more or less ceased by old solidified grease and grime. To properly solve this problem the gripper mechanism needs to be disassembled, cleaned, greased and re assembled. This job isn’t too complicated, it takes some time and it is important to keep track of the order of the parts and the gears.

First make sure to park the gripper at a location where there is no records in the magazine. Then disengage the motor from the gripper mechanism in order to be able to rotate it manually through gear #15. It is possible to rotate the gripper mechanism using the small tab at the bottom of the motor. But it is a tedious job to do that since the rotations goes through the motors gearbox and you need to make a lot of turns to complete a record loading sequence.

Next step is to carefully knock out the lock pin #25. Once it is out it is possible to separate the inner gripper (#23) from the gripper reversing assembly (#21). There is a square hole at the bottom of part #21 where you can knock out the square shaft of part #23 in case it is ceased. At this point you can also remove the gripper arm (#22). In some cases it might be enough to clean and grease these parts and assemble the gripper again. But I think it is well spent time to disassemble the rest of it and clean and grease also these parts to ensure smooth operation. For next step rotate the gripper assembly to point straight up, this is to be able to slide out gear #12 and # 13 from the gear at the gripper shaft assembly below (#14). Make a note (and take pictures) of the location of each of the three gears to make sure you put them back in the same position, else the gripper will not work. First remove the trunnion shaft button (#11) using a screw driver, it’s just to pull it straight out. Then remove the screw that locks gear #13 to the trunnion shaft. This screw might also hold the needle brush mechanism. Remove the gear #12 and #13 from the shaft (#10) and then slide out the shaft. The spider (#8) is now also free to be taken out of the mechanism. Clean the parts from old grease and grime and lubricate them with new fresh grease and put everything back in the reverse order. Make sure to engage the gears in the same way as they were before you took the unit apart. Rotate the mechanism manually a couple of times to check that it works properly before reconnecting the motor.