4
\$\begingroup\$

I am restoring a jukebox from 1953 (AMI E-120). Everything is going fine except the main drive motor, an A/C induction motor, cannot start under the load of the platter. It starts fine when the belts are off, but under full load, it won't start. And once I start it with my hand, it runs fine.

That makes for a pretty worthless jukebox.

This isn't actually my motor, but it looks a lot like it enter image description here

(The pics above are of another one that looks like mine)

I've taken the motor apart, and cleaned and oiled everything. It looks spotless, but it still doesn't have the guts to start the player.

What steps would you do next? Have the magnets gotten weak? Or do the coils need re-wiring?

Thank you in advance.

\$\endgroup\$
  • \$\begingroup\$ Product repair questions are off-topic here. The first thing you need to do is to understand how this was supposed to work. There is essentially no such thing as a single phase AC induction motor; any induction motor that can run off a single phase employs one trick or another to create some phase shift or other starting torque. To get anywhere, you need to understand which technique this motor employed... and why it is no longer working. If there is a phase shift capacitor (and I'm not saying there is...) it may well be long dried out and useless.d \$\endgroup\$ – Chris Stratton Aug 4 at 1:56
  • \$\begingroup\$ probably just needs some lubrication. \$\endgroup\$ – Jasen Aug 4 at 7:05
  • \$\begingroup\$ @Jasen - I had wondered about that too last night. I took it apart and added some light lubrication. It spun better by hand, but still didnt' have the umph to get the platter spinning by itself. I'm not ruling it out, but I'm thinking something is wrong with them otor \$\endgroup\$ – Dicer Aug 4 at 19:21
7
\$\begingroup\$

The Visible bit of bright copper is part of a shading ring .Your motor is single phase and relies on the shading rings for starting torque .When you strip the motor check the integrity of all the shading rings because you want rated torque .Also check the bearings ,they must be really free to turn .Starting torque of these types of motors is useless but they have not too bad speed regulation using no extra electronics .Now that winding looks not too good to me ,Give it a hipot test to avoid electrocution at power up .You could save your jukebox by using a more modern motor ,I have heard of this being done .

| improve this answer | |
\$\endgroup\$
  • 1
    \$\begingroup\$ This answer covers the most likely possibility. There is some possibility that the motor is a permanent-magnet synchronous type that has become de-magnetized. A better look at the rotor would determine that. \$\endgroup\$ – Charles Cowie Aug 4 at 3:18
  • \$\begingroup\$ Okay, I'll take it apart tomorrow and post a pic of the innards. Thanks to both you guys. \$\endgroup\$ – Dicer Aug 4 at 3:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.