MMF-2 motor noise

[Montycat]

I have someone's Music Hall MMF-2 turntable in the house. The issue is a screechy noise from the motor once it gets hot. It sounds a bit like an electric toothbrush once it gets going.

It actually took a long time before I could get it to happen. So much so I thought maybe it was location specific as it was not happening for me after running it several times and even leaving the motor running for hours. The other night though it finally did it after being on for an hour or 2.

It's definitely inside the motor, not suspension rubbing or anything like that. I found the motor also got very hot but perhaps this is normal. I worked some oil into it and it seemed to get better but it was also cooling off.

Has anyone had success in a long-term fix by oiling etc or should the motor be replaced? Are there other motors that are known to fit? It's a 120volt 300rpm one.

 

[cdk99]

You know far more than I do, and I haven't seen one of those motors, so this is general. If you have some moly additive for lube oil (use very sparingly) it will fill in voids a little bit, and is sturdy enough for motor vehicle gear surfaces. I have also found that Rotella T-6 tends to quieten motors better than other things I've tried. It's a synth 5-40, pours a little thicker than turbine oil, doesn't seem to slow things, react to anything, or gum up so far. By the gallon at Walmart is the only way I know to get it, being a trucker oil.

IIRC they had some difficulties with their motors for a while, might even be a recall or cheap replacement available from OEM.

 

[Montycat]

I think Musc Hall knows of the issue and might offer replacements but I am not sure at what cost.

The motor is well sealed and stckier oils would not get far. I've been using a TriFlow type which is good at penetrating but not perhaps to the bottom.

 

[hoodie]

Most likely time for a new motor. Needle Doctor has them in stock for half a hundred. While you are at it, a more rigid mounting in place of the rubber bands and grommets helps tremendously with speed stability.
-Matt

 

[Montycat]

The person who owns this might not want to buck up for $100 which is likely what it will cost in Canadian by the time I order that.

 

[cdk99]

If they are resigned to possibly losing it anyway, might be worth trying stronger measures to get inside the motor. I'm sure we'd all be interested in the guts. Meanwhile a note to Mr Hall might work out...
http://musichallaudio.com/contact-us/

 

[Montycat]

I finally got around to this project. The turntable has been mine for a few months after we came to an arrangement. I traded her a fully functional and decent turntable I had tuned up, an Akai I think (can't remember), for this non working one and she also gave me a Dual 701.

I bought a 16 Volt Pro-Ject motor from another AK-er and a similar one to what I have from the same guy. The 120v one he sent me probably does the same thing as he said it was removed from another table. However before installing the 16 volt model, which will require a bit of extra surgery and different circuitry, I decided to try to resuscitate the original. Not successfully however.

It came apart pretty easily. There are slots and a gap so a screwdriver easily pries the case apart. I cleaned old, somewhat cakey, lube from top and bottom and added a bit of grease and put it back together. Reassembled and running, it was making a similar noise to before within about half an hour. Back to Plan A

Music Hall MMF-2 motor by Buhduh, on Flickr

 

[Bob_in_OKC]

I had this issue with a MMF-5, several years ago. I bought a replacement 120V motor from Roy Hall and all was well after I installed it. My story on another forum:

http://forums.audioreview.com/analog-room/mmf-5-back-action-34415.html

 

[Montycat]

Thanks, good pics.

Since I have the extra 120 volt motor, I'm going to open it too just for the heck of it. However I expect I will be installing the 16 volt one I have. The part I am not sure about is the circuit required. The motor has a little diagram on it with a couple of resistors and a capacitor but no indication of values. Any ideas? There is a cap already in the 120v circuit and I expect it's just for spark suppression but not sure on the resistors.

 

[Bob_in_OKC]

This is a Debut III that I think has that motor. If you open it, I think you have a 50% chance of getting it back together correctly. I’m not entirely sure about that. If it’s wrong, it could turn the wrong direction.

 

[Montycat]

Thanks Bob! That looks very much like the 120 v version I have. Can you see the component values on those caps?

I also can now see where the 2 little rubber bits fell out from which is good. Here's mine before I unsoldered the original motor.

 

[Bob_in_OKC]

The spark capacitor says 272M 500V. The phasing capacitor says 8.2 uF 100V. Are you planning to get the wall wart for the low voltage motor?

 

[Montycat]

The spark capacitor says 272M 500V. The phasing capacitor says 8.2 uF 100V. Are you planning to get the wall wart for the low voltage motor?

I have it already and the socket too. I got it at the same time from @hoodie (I think). It was an aborted project of his which he offered when I was first on this thread.

 

[Montycat]

Well it's working now! No noise so far from the 16v motor though it doesn't have much torque. I have to give it a push.

I also mounted it rigidly as Hoodie did above.