Magnavox motor

Electrically amplified phonographs or radio/phonographs and related components (approx. 1928-1990).



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Dewey
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Magnavox motor

by Dewey » Fri Dec 08, 2006 1:58 pm

I have a Magnavox Imperial Micromatic, and lately the motor fan has been hitting the underside of the motorboard. There doesn't seem to be any vertical play in the capstan, and the rubber motor mounts are still pliable, so not sure why this is happening. It originally only happened during the change cycle, but now seems to be during play as well. Any ideas on a repair?

Thanks


Thom
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by Thom » Mon Dec 11, 2006 12:47 am

Could it be that your motor mounts are becoming too pliable? I've seen some motor mounts rot out that way and can then no longer hold the motor in position. The older it gets the worse they get which sounds like what you are describing here. You could also check to see if the lubricant is drying out on the turntable shaft and is now dragging which would also pull your motor out of position while trying to spin it. Hope this helps.

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Record-changer
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by Record-changer » Mon Dec 11, 2006 8:17 am

If this is the Collaro Conquest, or Magnavox 400 or 420 series, the motor fan is held in place on the shaft by a friction collar spring. A good tug can push it up or down. Something may be pushing it up (a foreign object under the changer?), or the friction spring may have failed. Overlubrication can do this too.

Adjusting the height of the step drive surfaces on the motor shaft also moves the fan. There is a second adjustment for idler wheel height on the idler jockey assembly.

Adding my grommet motor mount isolation trick on the Conquest requires adjusting the drive surfaces and fan height.
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Bobby Basham
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by Bobby Basham » Wed Dec 13, 2006 3:40 am

[quote="Record-changer"]If this is the Collaro Conquest, or Magnavox 400 or 420 series, the motor fan is held in place on the shaft by a friction collar spring. A good tug can push it up or down. Something may be pushing it up (a foreign object under the changer?), or the friction spring may have failed. Overlubrication can do this too.

Hey, Larry....

I have a 600 series Imperial Micromatic, and its motor had a small screw just below the fan blades on the motor housing. Stupid me, I thought that it was a speed adjustment (like on cassette motors), and turned the damn thing. All Hell broke loose....the WOW and feedback was horrible. I did notice that if I turned the screw too far, the shaft scraped against it. The screw has since fallen out somewhere inside the cabinet and I'll locate it later. For now, the turntable has to "warm up" for about 10 minutes before the speed stabilizes. Why did they use that tiny screw? This is the first motor I've noticed with that. None of my schematics break the motor down in detail.

BobbyB
Tucson, Arizona


Topic author
Dewey
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Location: Tampa, FL

by Dewey » Sun Dec 17, 2006 4:23 am

Hey guys, thanks for the replies. I've looked for foreign objects and found nothing. The motor mounts seem fine. Now the changer has picked up a new bad habit which I believe may be related to the problem--every five seconds or so, the turntable slows down for a tiny bit. Even with the platter removed, I can hear the motor doing it. However, with the motor on but with the drive wheel removed, the motor runs steadily. So the problem is with the drive wheel??

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Record-changer
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by Record-changer » Tue Dec 19, 2006 7:06 am

The motors in those can go dry with age. Proper lubrication requires getting oil in the felt pad in each of the two bearings.

The drive wheel has probably hardened with age. If you can get some from a radio TV repair supply house, Caig CaiKleen RBR does a great job of restoring the surface. If the surface is damaged, the wheel must be replaced or re-tired.

The second (larger) wheel drives the change cycle.

Also check the spring which tensions the drive wheel, and the pivots of the jockey assembly. Binding pivots can cause drive failure too. Clean and oil them.



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