Music Hall MMf5 motor noise

C

calman46

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Joined
May 9, 2012
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MA
I can hear the motor running on my MH turntable and there is scorching on the motor shaft. I am the original owner and didn't play it to death ,I have other TT's. The motor is still playing at the right speed . Does the motor shaft scorching indicate that the oil impregnated bushing has dry out ? Is this motor repairable ? I found Bluz Bros website and they drop in replacement motors, any suggestions?, thanks
 
The heat is caused by friction, so yes, it's a lubrication issue.
I'd take the motor out, take it apart, clean all the old lubricant and dust out, and re-lube it. Keep the original motor rather than replace it.
Electric motors do need periodic maintenance.
Here's a photo of the last unit I disassembled, cleaned, and lubed. A Robo Fan. :)
 

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I was able to take the motor apart . I was thinking just redistributing the original lube paste ,its not dry up and there's plenty of it, clean too. The bushings appear to be brass, not bronze anyway. All I have is super lube and light weight turbine oil which will probably run out. I can polish the shaft.IMG20230614101729[1289].jpgIMG20230614101749[1288].jpg
 

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That grease looks similar to Lubriplate 105. I wouldn't reuse the old. New is readily available, perhaps down at the local auto parts store.
Also check for drag from the platter causing motor heating.
Many of us use Mobil 1 or any motor oil on our turntables. I fill my oil squirt cans with whatever is left after doing oil changes on the cars.
My AR XB still has the original motor and bearings since I bought it new in about 1974. It's seen nothing more than automotive engine oil.
 
I don't see any "scorching". Even if it was scorched, just playing it wouldn't cause that to the thick steel shaft.
 
I didn't use the old grease it looked ok but had a waxy stickie feel to it . I went with Super Lube in motor and some capstan lube I have for a Revox B215 for the main bearing. The manual suggested Mobil 1 or any synthetic with Teflon for the mail bearing, I think capstan lube fits the bill. The TT is running quiet now, time will tell. Thanks for all the replies. There wasn't any scorching maybe just old cooked in lube . The shaft cleaned up pretty good ,there is what might be and oil retaining line etched in it.
 
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The super lube didn't last the noise is back . The TT ran quite with no record when testing 3 for four times this week. After playing one LP the noise is back and the noise is there with or without a record on the platter or the belt connected .The motor is hot but I can touch it. When the motor cools downs its quite again. Besides the two motor bushings could something else in motor be causing this noise? I thought maybe a heavier lube but I'm not sure now .I'll look for Lubriplate 105 . In the mean time I have some Exxon Ronnex MP.
 
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Perhaps the issue is platter bearing drag overheating the motor. I have no idea how that table is constructed, but my AR-XB uses a plain babbit bearing to support the shaft sides with a single ball that the platter shaft rotates on, in the bottom of the well. Motor oil is the lube.
If the ball was missing, the platter would still spin, for a while, until the motor failed.
 
The bearing is oiled and uses a white plastic-looking disc at the bottom to support the spindle. It is the original belt maybe that is dragging . The speed was never an issue so I haven't replaced. I'm going to run the motor with no belt .
 
when motor starts getting warm (no belt connected) the noise starts also. The hotter the motor gets the louder the noise.
 
Try it again with light oil. That super lube is silicone based no? ProbBly need to clean that also.
 
I think the shaft (pulley side) has flat spots on it . With the motor in half's if I back out the shaft it spins smoothly all the way in it fells like step audio pot.
 
My AR also uses a Delrin plastic disk at the bottom. The ball sits on the disk. Make sure your not missing a ball.
If your motor shaft is worn, then there you go. But realize the magnets and windings as they interact can also make it feel like a "stepped attenuator".
 
calman46 said:
I think the shaft (pulley side) has flat spots on it . With the motor in half's if I back out the shaft it spins smoothly all the way in it fells like step audio pot.
Click to expand...
Pics pics pics. Sounds like a thrust washer worn or missing in the motor.
 
George S. said:
My AR also uses a Delrin plastic disk at the bottom. The ball sits on the disk. Make sure your not missing a ball.
If your motor shaft is worn, then there you go. But realize the magnets and windings as they interact can also make it feel like a "stepped attenuator".
Click to expand...
Probably shaded pole motor, do any TT’s use permanent magnet?
 
Looking at the bearing with the big eyes it its white ball . I agree I think the stepped feel is normal . There were some marks on the shaft that came with 1000/3000 grid spinning in my drill press. The motor bushing must be bad. I will mostly just buy a new motor and belt . I give one more try see if it gets noisy.
 
That’s interesting.....I’ve had a similar issue with background noise on older gear, and it really makes you appreciate how clean digital sound is. Honestly, it’s moments like this that make me glad I use Spotify APK for most of my listening, since there’s zero hum or motor hassle.
 
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