Rock-Ola 460 very faint sound left side

[rockolarick]

Hi again,

Rockola Rick is back.  He thought he had everything fixed, but found another issue after playing with it some more.  I thought I would start a new thread in case this is happening to somebody else.  I had a hard time following any troubleshooting in the manual as the suggestion was to replace the amp.

1. When picking up and placing back a record, an annoying static sound can be heard from the speakers. Goes away once the record starts playing and when the gripper motor stops moving.  Could this be a loose ground somewhere in the gripper motor?

2. The entire left side of the speakers are very faint.  Things I have tried..

    Switched L/R wires on Aux Speakers Terminal Board. Result - Right side was faint.
    Adjusted the balance. Result - turning all the way to the left turned off the right side and could barely hear the left side.
    Adjusted the Gain - nothing happened
    
I tried to follow this post on a Rockola 1494 - jukeboxaddicts.proboards.com/thread/582/rock-1494-sound-right-side

Here were some suggestions - 
swap inputs - Are these the 2 inputs in the pre-amp? so swap the left and right one? 
could well be a poor cartridge - I couldn't find this part in the manual. Where is this and how can I test it to be poor?
also check volume control - How do I test this?  I unplugged it from the amp and cleaned the pins and am able to adjust the volume successfully
If no change, it's the amp-- if tube (valve) type, swap tubes - I assume this is on an older model?  I didn't see anything I could pull out and swap.

The fix for this jukebox was this - "I found a fault at the first tube that the right input signal sees"  Is this on my model, if so, where can I locate it? Again, I couldn't find anything in the manual to locate the first tube.

Sorry for all of the questions. Thanks for all of the great help you have provided.

[whammoed]

Did you try swapping the left/right inputs from the tone-arm cable? That will narrow it down between the tone-arm cable/cartridge/ stylus and the preamp/amp/speaker connections etc.

[jukenorman]

If you are getting noise when the gripper motor is running, you should probably start by checking that mute relay in the amp. is operating OK.

Norman.

[rockolarick]

Love this forum. I needed a little help on where to start and found the issue. I am getting continuity on the L and LG, but NOT the R and RG on the cartridge. Is there any cleaning I can do to the cartridge or stylus, before ordering a new cartridge?

Thanks jukenorman, I am going to check this next.

[whammoed]

You are measuring at the cart and not through the tone-arm wire correct? (just ruling out broken wire...had that issue on my Wurlitzer)
I would have expected no continuity on the left side since that is where you are having an issue. Hooked up backwards maybe?

[rockolarick]

Did some more testing and a little more confused. Here is what I observed.

Did continuity test on tone arm wires only - tested ok
On cartridge, getting continuity between the L and LG, but NOT the R and RG
This is what is throwing me off, I switched the yellow and red wires (L/R) in the cartridge and played it and now I hear faint sound coming out of both speakers. I was hoping just swapping the wires would have just switched the faint sound over to the other speaker, but wasn't the case.

Any ideas?

[whammoed]

Sounds similar to my issue that ended up being the tone-arm wire. Ended up having breaks in both left and right but was hard to track down testing continuity since moving the wires made the breaks make contact intermittently.
Try moving the wire around while playing. If the sound goes in and out that's your issue. Won't rule it out as not being an issue of course.
You could also have multiple issues of course but best to keep it simple first.

[rockolarick]

Thanks for the suggestions. I tried playing a record and moving the wires around and didn't fix the issue. I think you are right, I think there are multiple issues. Is it safe to say that if I have continuity between the L and LG, but not the R and RG that the cartridge is probably bad? If so, I will get it replaced, then worry about the next thing up the line on the left side.

[whammoed]

If you aren't getting any kind of resistance reading across R and RG then yes I would say it is bad.

[rockolarick]

Update - I ordered a new cartridge. Will post the results after receiving.

Also, I think I found the issue on why one of the channels had no sound. If you remember, when hooked up correctly, I had no sound coming out of both channels. One channel I think is because of the cartridge. The other channel I had to investigate, so I started with the preamp boards and switched them and got sound out of one channel. So then I switched the boards back and then pulled out and swapped the IC L&R that has 8 pins and this was the fix. the working one has 48934 AA7542 on it and the non working one shows 48934 RP7601. When doing a continuity test the working one shows 1600 and the non working one shows 770.

Could somebody explain this part and is the lower reading the cause of the speaker not working? Also, I am looking for a replacement part and I checked out the FAQ on this site and couldn't find a match from all of the websites listed. I did a google search and somebody stated that the 741 dual op amp could replace the 48934 part number. Could somebody confirm this?

Thanks again for all the help.

[jukenorman]

Yes, a 741 dual op amp can be used to replace R-O part number 48934. What cartridge did you order as a matter of interest?

Norman.

[rockolarick]

Thanks Norman. I will also get that ordered and report back.

After doing research, here is the cartridge I ordered. AT3600. I've had good luck with this site.

www.needles4jukeboxes.com/rockola-cartridges.htm

[rockolarick]

While I wait for my parts I started trying to diagnose the static coming out of the speakers when the gripper arm is moving. Here is what I have tried.

While jukebox is waiting for a selection I put my finger under the needle and did not hear any static coming out of the speakers, so I assume the mute relay is working.
Next, I selected a record, static was heard once the gripper motor started. Once the record was done playing and gripper motor started again, static was heard.  Once the gripper motor stopped and the magazine motor started, the static stopped.

Next, replayed a record and let the gripper motor place the record back.  During this process, I switched it to scan mode, then to the off position while record was on its way back. I then put my finger on the needle and I did hear static, so somehow it is not muting when the micro switch #3 in the back is on.

I don't think the microswitch is the issue because when the jukebox is waiting for a selection, it was muted.

Any ideas on where to look at next?

[Ron Rich]

Yea, The schematic ! See what's supposed to hold the mute relay on, during the time the gripper motor runs-?? Ron Rich

[jukenorman]

You could always link out micro switch 3 as a trial while the gripper is operating - that would prove the switch.

Norman.