Buzzing motor - MMF-5

[02audionoob]

Anyone here ever have any trouble with one of those little motors you see in a Music Hall, Pro-Ject or Rega turntable? Mine buzzes when it gets hot and I'm looking around to see if anyone has ever solved that.

[poppachubby]

Anyone here ever have any trouble with one of those little motors you see in a Music Hall, Pro-Ject or Rega turntable? Mine buzzes when it gets hot and I'm looking around to see if anyone has ever solved that.

you talking about a buzz that can be heard externally or through the stylus? BTW I know nothing that could help you, sorry man. I hope it's not something serious, real shame man...

[02audionoob]

I mean the motor itself makes the noise. Maybe it's more of a whine than a buzz. The motor is pretty simple...a magnet spinning in a steel case that splits open in half. The noise happens usually only after it has been running a long time...probably 2 hours or more...long enough to get hot to the touch.

http://farm3.static.flickr.com/2555/3977140527_c702e76784.jpg

[Luvin Da Blues]

Sounds like a bearing problem to me.

[poppachubby]

If you can gain access to the bearing, photograph it noob, I would like to see. If it's not sealed you can probably get away with a bit of penetrating oil for now. I assume you've inspected it for anything that might be loose and grinding...with moving parts heat means friction. It seems unlikely that a quality bearing (that we assume Music Hall have used) would not be able to handle the load of a platter infinitely.

The best solution would be to somehow watch the motor in action, anyway possible?

[02audionoob]

If you can gain access to the bearing, photograph it noob, I would like to see.

That's it in my previous reply. The only moving part is that round magnet on the left.

[poppachubby]

hhmmmmmmmmmm....have you got some super tough penetrating oil? With a rag, absorb a small amout and rub any areas that are moving. Give that a test run...

[02audionoob]

I put about 8 drops of sewing machine oil in the bottom half and put it back together. I figure surface tension of the oil will draw it up around the bearings. It's on a test run at the moment. If I resort to the penetrating oil I'll need to go out and buy some.

[jrhymeammo]

I hope your TT motor is okay and is nothing serious.
I would contact MH about the motor overheating.

Assuming MH and PJ TT assembly is basically the same, I have a few questions.

Have you removed the motor mount screws?
Are you using a correct 16v power supply?
Have you inspected your belt and the spindle platter?
Perhaps the self-lubricating motor has run dry. You may want to use a drop of synthetic motor oil as MH suggests.

Good luck and best wishes,
JRA

[02audionoob]

I don't know if the amount of heat would qualify as overheating or not. It's not scorching hot...just sort of hot. There's a fairly thick plastic shell above the motor and I've removed that. Plastic seems like too good of an insulator to have there if I'm having heat issues.
<P>
I might contact MH if the problem continues, but I'm afraid the answer there might just be to buy a new turntable. I'd buy a new motor from Needle Doctor if it came already attached to a power cord. I haven't asked them if it does, but I'd guess it doesn't. The soldering looks a little intricate...beyond my skill level.
<P>
To answer your questions...the motor mount screws are in place. The power setup is original to the turntable...no outboard transformer. The belt and spindle check out good.
<P>
And then to answer a question with a question...What do they mean by "self-lubricating"? Does that mean the bearings do or don't need oil? Or that they shouldn't need maintenance with additional oil later? In the manual...at that comment about adding oil...it seems like they're talking about the platter bearing rather than the motor bearings. Do you think they mean the motor?
<P>
In any case, I'm guessing they didn't mean to crack it open like I did. But it's been running continuously since I put the oil in...certainly more than a drop...and it has been quiet.

[jrhymeammo]

To answer your questions...the motor mount screws are in place. The power setup is original to the turntable...no outboard transformer. The belt and spindle check out good.


And then to answer a question with a question...What do they mean by "self-lubricating"?






Arent the mounting screws meant to be removed? If they are same as the PJ deck, I was under the impression that mounting screws need to be removed to suspend/isolate motor vibration from the deck. And also to allow the motor to spin freely as it was designed. Have you always had screws in place? If so, the mounting screws may have applied too much downforce stress onto the motor assembly.


As for "self-lubricating" I have no idea. Some motors and spindles are designed to pump oil back to contact surface to minimize possible wear.

[02audionoob]

Arent the mounting screws meant to be removed? If they are same as the PJ deck, I was under the impression that mounting screws need to be removed to suspend/isolate motor vibration from the deck. And also to allow the motor to spin freely as it was designed. Have you always had screws in place? If so, the mounting screws may have applied too much downforce stress onto the motor assembly.

I thought you meant the screws on the flanges of the motor, which are in place and are required to hold the motor on the bottom deck. As for those screws that hold the top deck to the bottom deck...yes...they are intended to be removed and I have removed them. They go in those brass threaded holes you can see in the photo. The hole in the top deck is much larger than the motor, so it wouldn't appear to apply any unusual pressure if the screws were in place, but of course the screws would defeat the purpose of the decoupled plinth.

At this point, I think cracking it open and putting several drops of sewing machine oil in the bottom solved it, although I wonder if that oil will congeal someday.