Continental AMI Juke Box Fault Finding

[rob1948]

Thanks guys. I assume removing the magazine motor is done from the front after first removing the Search Unit ? Or do I access it from the back after removing the magazine. Thanks Rob

[rob1948]

Hi Norman/Ron,
Have just re measured the DC voltage with no load 27V and operating the magazine it drops to 25V.Going to replace the rectifier diodes and condenser (1000mfd) and re check. Must be the problem ? Just checked I can access the DC motor from the front by removing the playmeter assembly. Thanks Rob

[jukenorman]

Hi Rob,
I imagine it could be done either way but my gut feeling is that it would be easier from the front with the search unit removed. There is also a drive coupling for the popularity counter and scan control unit to disconnect. Virtually nothing is easily accessible on the Continental so if you have the mech out, it's worth servicing as much as you can to save you having to return to it in the future.
Norman.

[Ron Rich]

Hi Rob,
I would NOT change the rectifier ! Look at it carefully-- if no "paint is peeling", it's good ! You do not want to speed up that carriage past where it should be, as it will start "breaking things"-- Clean up the motor first-- change the cap, and I think you will be just fine-- Ron Rich

[rob1948]

Hi Ron/Norman,
I can get a 1000 mfd 450V DC capacitor (51mm diameter x 106mm) physically a little larger than the original one currently installed and as a result of its size I am going to have to mount the capacitor on the outside of the Junction Box, but not ideal. The voltage, 450V DC should not be a problem, unless its voltage rating is less than the 32V DC out put from the rectifier? Alternatively I have a 1000 mfd 63V DC capacitor (16mm diameter x 36mm) which looks physically hopelessly too small ?? Maybe I should continue and try and source one identical to the current one installed ? Thanks Rob

[Ron Rich]

Rob,
Size on caps over the last 50 + years has steadily decreased. I don't know the value that cap was voltage wise, when installed at the factory, but it would be my guess that it was either a 35 or 50 volt item-- therefore, the 63 volt cap, will be just fine-- check the schematic, or parts list, to be sure -- Ron Rich

[jukenorman]

Hi Rob,
The 63V will be more than good enough, the sizes of electrolytic capacitors have reduced dramatically since 1960! As you have discovered!  Oops too late - the original was 50V I'm fairly certain.  You can fix the smaller capacitor in the original clamp using a plastic cable tie.
Norman.

[rob1948]

Thanks guys, I will install the 63V DC capacitor and return the bigger one for a refund. This will make life a lot easier. Ron, I have also checked the rectifier and no paint is peeling and so no need to replace it. Good news. Thanks. Rob

[phil]

Hi
look

www.west.net/~jay/jukebox/amijunction.html

Phil

[rob1948]

Hi Ron/Norman,

[rob1948]

Hi Ron/Norman, Well I have installed the Junction Box from my 'Donor' JB but still no improvement to the rotation of the magazine. I then replaced the condenser with a new 1000mfd 250v DC unit, still no change. To rule out a faulty rectifier I connected a 24v car battery to the +/- pins on the 4 pin plug, the magazine obviously turned slower as a result of the 24v supply. Slight improvement when I release the tension on the record retainer belt. The drive motor rotates at 28 RPM and based on a 5:1 gear ratio(20 teeth vs 100 on the magazine gear)the magazine should rotate at 6rpm and is only rotating at approximately 4rpm. I think this process of elimination can now only lead to the magazine drive motor being the problem as we have discussed before and therefore I have now no option but to remove the motor and give it a service and replace brushes if necessary. I am going to access the motor from the front of the JB by removing the play meter assembly and search unit. Is there any thing I should be marking before I remove components so I re-install correctly in order not to have to reset the JB's sequence of operation from scratch ? Norman did say I should lock the sprag relay before removing the search unit? Your response would again be appreciated. Thanks Rob

[jukenorman]

Hi Rob,
I think what I said was that if you were feeling lazy, you could lock the sprag relay before you remove the search unit - although it's not something I have ever done. The pin pusher adjustment is actually quite straightforward and is covered on page RCS-29 of the manual.

Norman.

[rob1948]

Thanks Norman, I have just come up from my workshop and thought I would 'bounce 'this off of you. I was thinking of un-bolting the entire JB mechanism complete from the cabinet(4 x spring mounting bolts or 6 x channel bracket bolts) and then lifting the mechanism up just high enough out of the cabinet to get to the magazine motor bolts. I will erect a small crawl over the Cabinet to lift it up. OR, slide the magazine end out from the back just far enough to be able to get to the magazine motor bolts, and obviously supporting the overhanging mechanism? I think this could work and save having to just about strip the JB mechanism to get to the motor. How does this sound to you? Thanks Rob

[jukenorman]

Hi Rob,
If you think that's the best way, then go for it. The mechs are quite robust, access is the problem with them. You shouldn't have any worries about removing the search unit though, it is quite easy to set up after you put it back.

Norman.

[rob1948]

Thanks Norman, I will keep you posted.