[Jukebox-list] Rockola 478 Reverse Relay. Chattering

Mon Dec 3 16:33:57 PST 2007

THanks Ron,

I found this message in the archives,

" [Jukebox-list] Re: Rockola 478 clicks
Janscott9 at aol.com Janscott9 at aol.com
Thu Jan 29 15:15:16 PST 2004

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I have a Rockola Mystic 478. When the record finishes or I hit the cancel
button it slowly puts the record back in a jerky motion and clicks in time
with
the jerks. The reverse relay on the power supply board in the back seems to
be
the problem but I have replaced it and there is no change. Does anyone know
what else would cause this and also were to get the capacitors to redo the
amplifiers?"

If I can trust his input then it's not the relay, However, I suppose it
could still be a switch somewhere. I think I will spend some time laying out
the sequence of operation from the large schematic that I have, - perhaps
that will give me a better understanding what's going on in this circuit.

John

-----Original Message-----
From: jukebox-list-bounces at lists.netlojix.com
[mailto:jukebox-list-bounces at lists.netlojix.com]On Behalf Of Ron Rich
Sent: Monday, December 03, 2007 11:44 AM
To: Jukebox mailing list
Subject: RE: [Jukebox-list] Rockola 478 Reverse Relay. Chattering

Hi John,
  Even if it's supposed to be normally closed, and you can hear it "click",
does not indicate that the switch is good. It may be "dirty, or pitted" and
unable to pass the current needed at that point in time.
  The only good test that I know for any switch is to use an analog meter on
the lowest ohms scale, and slowly push/release the switch while watching the
meter. If good, the switch will remain closed, with no meter mvement after
the "click" in both directions. If it "flops the meter indicator" it's bad.
  Ron Rich

"John D. Taylor III" <johndt3 at verizon.net> wrote:
  Thanks for the input Ron,

There are relays in the circuit,-the latch relying, and some cam switches.
However, the latch relay is a normally closed switch, and the micro switches
which is on the cam do not change position until the cam has been turning
for some period of time after the reverse relay is holding in by it self.
When I hold the reverse relay down by hand, I only hold it momentarily,
which is to say before any the cam switches change position,-therefore, it
seems unlikely to me that it would be one of those switches. Nonetheless,
at this point anything is possible. I appreciate your input. I could take
a picture of the magazine power Board on the schematic and send it to you if
you like.

John

-----Original Message-----
From: jukebox-list-bounces at lists.netlojix.com
[mailto:jukebox-list-bounces at lists.netlojix.com]On Behalf Of Ron Rich
Sent: Sunday, December 02, 2007 8:30 PM
To: Jukebox mailing list
Subject: Re: [Jukebox-list] Rockola 478 Reverse Relay. Chattering

Hi John,
I have seen that happen before---a long time ago, and I just have "fuzzy"
memories of a "Micro" (type) cam switch failure--or maybe a bad "slow down"
resistor--but this could be a memory of one of the later Wurlitzers or one
of the German "Wurlitzer" models.
I do not have the book on a 478 R/O
Hope someone else will chime in---
BTW: Jay is the lists creator--we all owe him, big time !.
Ron Rich

"John D. Taylor III" wrote:

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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