[Jukebox-list] Rockola 478 Reverse Relay. Chattering

[Ron Rich]

John,
  Thanks for the update !
  Ron Rich

"John D. Taylor III" <johndt3 at verizon.net> wrote:
  
Update,

For those of you that were following this thread I thought that I would give
you an update now that I have repaired the jukebox. First, I want to thank
everyone that has replied with their suggestions,-thank you.

Failing to discover the problem after trying all the suggestions, I decided
to order the manual. The manual was interesting and it provided several
sequence of operations diagrams that simplified things. Nevertheless, it
didn't tell me anything that I didn't already know. Frustrated, I decided
to return to basics and start from the beginning. I had taken it for
granted that I had to correct voltage because the LED light was on on the
regulator. But, by this point I decided to trust nothing. I got my meter
out with the intention of tracing the circuit voltage, point-to-point. When
I read the incoming DC voltage it was 20 V instead of the 34 that it should
have been,-I immediately switched to the AC scale, and there was 10 V AC
combined with the DC voltage. It all made sense then, the chattering of the
relay, the relay being able to hold itself in when I did it manually, and so
forth. Of course, from there it was simple. I went in the power supply and
changed the filtering capacitors, and the one on the front regulator board,
even though this one was good. I put everything back together and it is
working fine now.

It's funny how sometimes we get ahead of ourselves, forget the basics, and
start making assumptions, (How Often I Forget the Phrase, Check Your
Voltages.) I guess the strange part of this was everything did seem to be
working right with the exception of the gripper arm not wanting to return
the record to the magazine,-so I made the mistake of making assumptions
about the voltage.

Anyway, thanks to everyone for their help. Even though it turned out to be
a different problem than any of us thought of,- you did help me to affirm
that I was checking the right things in the circuit. At least if anyone runs
across this again we will have an added suggestion for the subscriber.

John

---- a-Original Message-----
From: jukebox-list-bounces at lists.netlojix.com
[mailto:jukebox-list-bounces at lists.netlojix.com]On Behalf Of John D.
Taylor III
Sent: Sunday, December 02, 2007 6:57 PM
To: jukebox-list at lists.netlojix.com
Subject: [Jukebox-list] Rockola 478 Reverse Relay. Chattering



Greetings all,

I have recently ran across a 478 Rockola reverse relay that chatters when
trying to pick the record up to return it to the magazine. During this
chatter, the gripper motor jerks in time with the relay until the record is
returned to the magazine. This is a very slow process. Unfortunately, I am
not as familiar with the circuitry on this jukebox as I would like to be. I
pulled the mechanism power Board checked the relay along with the
components in the related circuitry. All appeared to be well, with the
exception of two capacitors that were only a little out of tolerance,-which
I replaced. I noticed that when the record is canceled using any of the
cancel options if I activate reverse relay for a half a second with my
finger, then, it will stay activated until the cycle is complete. During
half sec that I am holding relay in by hand the transfer arm has not moved
yet, so, none of the micro switches has changed position while I am holding
it manually. The relay is self holding by the time the transfer shaft begins
to turn within the cam switches on the end. I did found one forum where
another mechanic had the same problem, he changed the mechanism control
Board completely, but it didn't fix the problem for him, so I think I can
eliminate the board.


Okay, since I may have made this a bit confusing, I'll summarize. When a
record is canceled the gripper motor begins a jerky movement to pick up the
record and return it to the magazine, and a reverse relay is chattering in
time with the jerk movements of the gripper motor.

I have the schematics, but not the manual. I really don't understand the
sequence of operations on this jukebox. However, I do have a schematic, and
I have tried to chase the circuit's all around this 9 foot square thing,
this is when I realized I was in trouble and needed to ask for help. Can
anybody help me with this problem? Can you tell me the sequence of
operations for the circuit? Have you ran into this before and know the
solution? I welcome any thoughts, and/or debates relating to this problem.

Thanks to whoever created this forum, it's been a great help to me in the
past and I'm sure it will in the future.

John


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