[Jukebox-list] AMI Carriage junction box RR relay arcing

[Ron Rich]

Aaron,
  Going from my great, but not too long memory, because I have mis-placed my "900 Mechanism book" (or did they call it a "record changer"), and notes--
  I think this is a problem with the "dynamic brake" circuit. I  seem to re-call that if you have replaced the selenium rectifier with a silicone type, there in lies this problem. The solution is to 1.) check and be SURE that all contacts in the circuit are making WELL. 2.) add a resistor in series with the output of the rectifier, to bring the voltage down to under 28vdc. (Sorry-don't recall the value--but think I used a 5w ww)
  My memory says that there should be no power to the magazine motor when that relay opens--it should have been shorted out (dynamic brake) when the pulled pin was sensed, by the "stopping switch" (either # 1 or # 2). I would think that somewhere, when you get the arc, there is a contact which should be open, that is closed---
  As for the fuse--AMi did increase the value of that fuse in later production from the 8/10 to a 1 amp SB. If the box with the rectifier and transformer does not have a 2 amp fuse in the primary circuit, I would suggest that one be added, as per later production units.
  Ron Rich

Aaron Heverin <aaron at vertasource.com> wrote:
  Hi all.
I'd like to put this out there on behalf of Joey because of a problem he's having with his AMI F...and for the exact same problem I'm having with MY G-120. While I'm not sure it's an actual issue that would cause a meltdown of the jukebox, it's an annoyance just the same. What happens is that the RR relay on the carriage junction box arcs every time the mech comes to rest and the relay opens and cuts the power to the mech. I had this problem on my G, and every time the arc would happen, the 8/10 fuse would blow. So after testing the relay...and making sure that all of the switch contacts on the relay were polished, I tried it again. Relay opens, pops the fuse. I was having the exact same problems with Joey's F...and when I went back to look at my notes, I found that quite a few of the Fs and Gs I restored had the same problem - plus or minus intensity of the arc per machine. On Joey's F, the arc was quite bright and powerful. It didn't seem to hurt the mech at all or hinder
 operation...it just opened and popped the fuse.

On my G, I had put in a 1 amp fuse and that seemed to solve the problem for a while, but every once in a while - in a way that was not in any kind of pattern to try and troubleshoot - the arc would be bad enough to pop the fuse. So I put in a 2 amp fuse. Now before any of you tune me out and start yelling :) - let me point out that I went through every ounce of the mech and carriage junction box to make sure that when the arc occured that something wasn't getting shorted out - and thus by putting in a larger fuse, I wasn't going to be causing any damamge to the mech or the main junction box. I assumed that since the arc was causing the fuse to blow - and not a dead short - that the 2 amp fuse would take up the relay's bang, but still pop if a REAL short occurred. Perhaps my thinking was wrong...and that's why I'm posting this question.

Any idea why that relay would be arcing so roughly? I've always seen some type of arcing in ALL of the relays in those jukeboxes....even in the credit unit. What I'm wondering is if the arc is occuring because there's too much current being pulled from some place. The only thing I can think of is the carriage motor since that's connected to the RR relay. But on both Joey's F and my G, the motor doesn't show any signs of being under a heavy load nor does it seem to be struggling to move the gripper arm. 

Like I said...this is more of an annoyance rather than anything else...but I'm curious because I'd like to not have an arc at all.

Thanks all!

Aaron Heverin_______________________________________________
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