1st Rockola 474 Newbie question on where to start...

Hello everyone, I'm new to the forums and wanted to see if I could get some advice/suggestions on a juke I picked up this weekend. It's a Rockola 474. The previous owner thought it had a bad amp and said the amp overload light was on but I don't think that's the problem. I do have the manual but it's not with me now so please excuse me if I use the incorrect terminology. This is a project I picked up for my dad (a recently retired electrician) and myself, so I'm hoping between this forum and our knowledge, we can get this box back up and running. Here's what we're observing:

When I plug in the box I hear a mild "pop" from the speakers which seems normal as if the amp is turning on. There doesn't appear to be a coin box (quarters drop to the bottom of the jukebox) so I'm wondering if that is my first problem. I found a post on here about soldering some wires together for free play but I'm not sure if the absence of the coin box would deter this. Does the juke need the coin box to work? Nothing happens when I make a selection. Opening the juke, the service switch/lever does allow the record carousel to rotate along with the turntable and pin bank. Unfortunately I can't get the needle over and if I rub the needle with my finger I don't get any sound. Most of the lights turn on and the box looks relatively clean. The "make selection" and "record playing" lamps are on but obviously I can't make a selection and the record isn't playing. We have yet to test the fuses. Is there a way we can manually test the record playing function?

Any suggestions would be great. Thanks.

Eager to learn,
-david

David,

First of all, I assume you are using "coin box" in reference to the
coin acceptor ( unit to seperate the coin denominations and sent them
to the proper coin switch ). The acceptor is not necessary, nor is
the coin switch assembly. There should be a credit button on the
credit unit, which if memory serves me, is on the left sidewall as you
are looking at the mechanism from the front of the cabinet. This
momentary slide switch should add one credit for each actuation.

Second, the overload lamp on the amp will be lit any time the unit is
not attempting to play a record. It is lit when the mute circuit is
engaged OR when the amp "senses" a speaker overload / short
condition. The thump you hear on power up is probably normal, but may
indicate a degrading parts in the amp.

Third, the Write-In / Read-Out drum has two rows of selector pin
around its outside edge. These pins are "set" in the direction away
from each other when they are selected. You should be able to
manually move one of the pins to force a selection sequence. Toward
the back upper side of this drum unit is a micro-switch which is
acutated by an arm including a spring steel armature when one of these
selection pins are in the selected position. This switch enables the
scan circuitry to operate.

Last, if you have the service manual, it should contain a sequence of
operation which will not only familiarize you with what the juke
should be doing, but also the terminology of the major assemblies and
parts.

Respectfully,
David Rebber
Jordan Amusement Co., Inc.
Lubbock, TX

David, thanks for the tips, it helped us see some operation with your manual pin suggestion. I was mistaken, we do have a coin acceptor, it's just not working properly. Unfortunately we haven't had luck getting the credit button to work but we have been able to give the juke credit using the coin acceptor.

Here's where we're at now...

Using your suggestion about manually selecting a selection pin we can get the record to select and the tone arm over to play the record. Unfortunately we're not getting any sound but that's going to take some more investigating with the tone arm and amplifier to say the least. I did see the the input from the tone arm to the amplifier stripped at one point, I imagine that may have fried the amp.

We're having a problem getting the selector motor to move after making a selection. It's a little hard to reach but we found access in the back is best. We still have some testing to go but I'm happy with the progress we've made so far. The manual is a great help but any tips from the forum are great as well so please keep them coming!

Thanks! -david

Originally Posted by DRebber

David,

First of all, I assume you are using "coin box" in reference to the
coin acceptor ( unit to seperate the coin denominations and sent them
to the proper coin switch ). The acceptor is not necessary, nor is
the coin switch assembly. There should be a credit button on the
credit unit, which if memory serves me, is on the left sidewall as you
are looking at the mechanism from the front of the cabinet. This
momentary slide switch should add one credit for each actuation.

Second, the overload lamp on the amp will be lit any time the unit is
not attempting to play a record. It is lit when the mute circuit is
engaged OR when the amp "senses" a speaker overload / short
condition. The thump you hear on power up is probably normal, but may
indicate a degrading parts in the amp.

Third, the Write-In / Read-Out drum has two rows of selector pin
around its outside edge. These pins are "set" in the direction away
from each other when they are selected. You should be able to
manually move one of the pins to force a selection sequence. Toward
the back upper side of this drum unit is a micro-switch which is
acutated by an arm including a spring steel armature when one of these
selection pins are in the selected position. This switch enables the
scan circuitry to operate.

Last, if you have the service manual, it should contain a sequence of
operation which will not only familiarize you with what the juke
should be doing, but also the terminology of the major assemblies and
parts.

Respectfully,
David Rebber
Jordan Amusement Co., Inc.
Lubbock, TX

So our write motor appears to be bad. I'm going to try to see if I can fix it by giving it a good cleaning but if that doesn't work, I'll probbably need a new one. Does anyone have a write motor (I believe that part number is 401A0-3A) for a Rockola 474, 473, or equivalent? Thanks!

Originally Posted by

David, thanks for the tips, it helped us see some operation with your manual pin suggestion. I was mistaken, we do have a coin acceptor, it's just not working properly. Unfortunately we haven't had luck getting the credit button to work but we have been able to give the juke credit using the coin acceptor.

Here's where we're at now...

Using your suggestion about manually selecting a selection pin we can get the record to select and the tone arm over to play the record. Unfortunately we're not getting any sound but that's going to take some more investigating with the tone arm and amplifier to say the least. I did see the the input from the tone arm to the amplifier stripped at one point, I imagine that may have fried the amp.

We're having a problem getting the selector motor to move after making a selection. It's a little hard to reach but we found access in the back is best. We still have some testing to go but I'm happy with the progress we've made so far. The manual is a great help but any tips from the forum are great as well so please keep them coming!

Thanks! -david

We replaced the motor, we're almost at functional operation! We can get a selection to be placed on the turntable however we're still not getting any sound. Could an amp cap kit fix our sound problems? Is it possible that the wires coming from the tone arm into the amp could have shorted and shorted the amp input? Any suggestions would be greatly appreciated.
Thanks,
-david

David,

Here's where having spare assemblies really simplifies the troubleshooting procedure...
If your overload lamp does not turn off when the record is placed on the turntable, your mute circuit is not disengaging or there is a problem from the amp forward.
If it goes off, your problem may lie anywhere. It would be great if you could put some other input into the amp to see if you have amplification. Unfortunately, the tonearm input is that goofy three post connector, but you could jumper in a signal to the posts on the inside of the amp cover. ( A magnetic phono level input would be best. ) This will help determine if the amp has any output whatsoever and whether the needle, pickup cartridge and / or tonearm cable may be at fault. Remember, though, that this test has to be done while the record on the jukebox is attempting to be played.

Let us know how you make out.

Somehow, my previous post did not translate properly from the
collectingbanter.com forum. It was posted to la.kings question about
his amp. ?????

At any rate, if your selections are not writing in properly, cleaning
the slip rings and contacts may help. There is also a relay involved
in the pin setting sequence.
However, it evades me at the moment which one in particular fires that
circuit. I'll try to find my schema and run it down.

Thanks David, We did clean the slip ring contacts which made a drastic improvement. We didn't have enough records in the box to test it accurately but it has been much more responsive. I came across some 45 so we can give it a better test. So far all our relays have tested fine, I do recall reading a post about cleaning the relay related to this to help improve the write process but hopefully that isn't an issue for us. Sound seems to be our next hurdle (which you address already).

Originally Posted by DRebber

At any rate, if your selections are not writing in properly, cleaning
the slip rings and contacts may help. There is also a relay involved
in the pin setting sequence.
However, it evades me at the moment which one in particular fires that
circuit. I'll try to find my schema and run it down.

WE HAVE SOUND! Apparently our initial fuse check wasn't as accurate as I thought it was. After replacing a fuse we now have sound!

We're now going to go back and fine tune our selection process. Thanks for your help David, you've been a great asset. I'll let you know how our fine tuning goes. I'm so excited, this forum has been a great asset!

-David

Originally Posted by DRebber

David,

Here's where having spare assemblies really simplifies the troubleshooting procedure...
If your overload lamp does not turn off when the record is placed on the turntable, your mute circuit is not disengaging or there is a problem from the amp forward.
If it goes off, your problem may lie anywhere. It would be great if you could put some other input into the amp to see if you have amplification. Unfortunately, the tonearm input is that goofy three post connector, but you could jumper in a signal to the posts on the inside of the amp cover. ( A magnetic phono level input would be best. ) This will help determine if the amp has any output whatsoever and whether the needle, pickup cartridge and / or tonearm cable may be at fault. Remember, though, that this test has to be done while the record on the jukebox is attempting to be played.

Let us know how you make out.

CORRECTION:
It wasn't exactly our fuses so much as our fuse holders. We replaced the holders and THAT gave us audio.

Last stop on the list is the selection keyboard. Some of the buttons aren't selectioning as easily as they should. We're working on adjusting them but I'd say we're about 95% working!

Originally Posted by

WE HAVE SOUND! Apparently our initial fuse check wasn't as accurate as I thought it was. After replacing a fuse we now have sound!

We're now going to go back and fine tune our selection process. Thanks for your help David, you've been a great asset. I'll let you know how our fine tuning goes. I'm so excited, this forum has been a great asset!

-David