Rock-ola 424 gripper motor problem

Hello all, I'm a newbie here so please bear with me.
I was recently given a Rock-ola Princess Royal 424 Jukebox by a friend for repair. I was told it was in working order before it went into storage about 10 years ago. This is the first time I have worked on a jukebox, so any help would be greatly appreciated. This thing was filthy and the gripper arm was completely frozen up. I have removed, disassembled, degreased and thoroughly cleaned all of the dirt, grease and grime that had accumulated on the mechanism. I reassembled and lubricated it with ND 20w oil and Lubriplate Areo grease as appropriate. After reinstallation into the cabinet I'm having problems with the gripper motor circuit. After selecting a title, it operates OK selecting and placing the record on the turntable but the gripper motor does not stop, continues to run and jams. By turning the service switch to off, manually turning the gripper motor back out of the jammed state and then tripping the interlock relay it will then reverse when the tone arm contacts close. This jamming also happens on the return cycle when the gripper returns the record to the magazine. I have checked the operation of the 3 micro switches with an ohm meter and they all appear to be functional. I have readjusted the cam to several different positions making sure the #1 switch lever is in the cam notch while the gripper arm is in the standby position at the end of the shaft rotation travel. I also checked the reverse and interlock relays. Each of the 3 coils has continuity through them and show no signs of overheating. Each set of relay contacts (both NO & NC) also check good (1.5 ohms or less) with an ohm meter. What am I missing? After numerous reads through the sequence explanation in the manual, I can't get it into my thick skull a true understanding of why this is happening. This thing is driving me nuts!

Thanks for your help,

Redneck Abe

Hi Abe,

I have a 433 and I have exactly the same problem. After I rewind the motor manually sometimes the gripper arm works just fine for a couple of records but then all of a sudden it doesnt stop after putting down the record on the turntable, jamming itself. I checked the cam wheels, the switches but nothing helped...

I looked for a solution for a long time but couldn't find it. Did you have any luck finding what's causing this?

Regards,

vds

The "usual" cause of this is a switch, or relay contact, that is not making "well". This can not be determined with a digital meter, only with a good analog meter,set to R(X)-1. Ron Rich

Did any of you guys solve this problem? I have worked for endless hours and am finally ready to give up on it. I feel like it must be micro switch #2a but everything when I test it everything sees fine.

I have a severe love/hate relationship with this machine.

Hi
I would check micro switch No. 3 in conjunction with interlock relay, either test it with an analog meter or replace it,also check for loose plug and wires
regards
clones

Hi
Also there is only one way the cam will sit over the micro switches, try and loosen the motor and cycle the gripper manually, this will give you a better idea of the operation of the micro switches
clones

I rotated the cam just a bit to make sure the micro switches would sit "perfectly". That didn't turn out to be the problem.

I will check micro switch #3 when I get home. I don't have an analog meter (just digital) so I might need to just replace it and cross my fingers.

I actually took a couple videos of it... let me know if any of you guys see anything that jumps out at you.

https://www.youtube.com/watch?v=k5Vnq_9JaKk

https://www.youtube.com/watch?v=P9Khq8uW170

Can't tell for sure, but it almost looks like it is attempting to reverse ? If not, check the relay to see if power is removed, and/or it has a "magnetized armature". Also--pulling the "common" off the switch prior to it going into the cam notch, might tell you if the switch is the cause. Ron Rich

Just wanted to say thank you for all of your help. I really have learned so much through the people on this board. I have also learned ALOT just by working on the jukebox. It has been a lot of frustration and very little happiness... until last night! I wanted to update my situation because I get so bummed when i read through someone's problem that is similar to my own and there is no conclusion.

I solved my issue and in case anyone else runs into the problem here is my checklist.
First the problem: The main cam was continuing to run past it's stopping point and it would then get stuck (because it over rotated). Bytheway, this wasn't the same Jukebox as the person who started this thread. I have a Rock Ola 1000 which has similar mechanisms as a few others (490, 494, etc)
Here is what I tried:
1) I adjust the cam so I had the microswitches hitting where I thought they should - No help
2) I replaced the #1 microswitch - No help
3) I was about to replace the reverse relay but instead decided to go back to #1 and adjust the cam again...
4) My success was adjusting the cam. This jukebox is different than any of my others (super frustrating). The cam has to be adjusted to an exact setting. You can not be off by even a mm. Once I had it perfectly adjusted I was good to go.

Thanks to everyone. After I had it going late last night I reloaded all of the records and cracked a celebratory beer while listening to some of my favorites.

Cheers!

Glad you "got-it" ! Thanks for posting it--
BTW, all switches, especially the "Micro Switch type" must be "perfectly" adjusted--they CLAIM that the reason for the design of that switch, is to have it "trigger", at exactly the same place, every time (IMHO--Not true, as they age). Ron Rich