Presto 6n motor speed problem

[Jccc]

Hello, my presto 6n motor is spinning a little to fast when cutting on 33. I noticed it right after cutting a record as the playback seemed a little slowed down.

I took a tachometer to check the speed and its spinning at 34 rpms. I then tested the 78 speed and its spinning at 77rpm.

Do you think it might be time change the rubber rollers? Or could it be a motor problem.
If its the motor is there somewhere on the motor where i can dial in the speed?

[Prestofan]

The size of the rubber idlers (or pucks) have nothing to do with the speed. Check the motor - have it cleaned, lubed, and bearings checked by a small motor repair shop.

Alan Graves

[markrob]

Hi,

I would not trust a digital tach unless it has a few decimal points of accuracy (e.g. 33.33). Any digital insturment is +/- .5 count in the least signficant digit by its nature. Use a strobe disk instead. You can determine the amount of speed error by counting how many lines pass over a set time.

Mark

[Jccc]

I got a new problem now with my motor. It has nothing to do with the speed now. It has to do with it sort of not working.

It just started today For some reason when i switch the lathe motor on. It does not spin. I have to take off the platter and turn the motor shaft by hand and then it starts to spin.

I then have to turn off the motor and put the platter on so i can set the lathe up to cut. Once its spinning everything works until i turn it off then i have to repeat the same process over again.

I put oil in it where it says to add it and it still does it. I was wondering if it needs to be regreased but i do not know how to open it up.

Has anyone had this problem before?

[tragwag]

I don't know for sure,
but it would seem that your start capacitor is failing.
it causes the motor to not have enough torque to start correctly, though it can hold its speed when it's moving already.

someone with more knowledge should clarify

[Jccc]

Now the motor does not even spin anymore. I was cutting a plate and then all of a sudden the platter stops.

Hopefully the motor is not dead! i felt the motor and it felt pretty warm.

Is the start capacitor located right next to the on/off switch? Could that be the cause of it not working?

[Angus McCarthy]

I had much the same thing happen to my 6N motor. Running fine all day and then after sitting cold it seized nearly solid. The ancient grease had finally coagulated and gummed up the bearings. The only thing that got it spinning again was gentle persuasion and a dropper of Oil of Wintergreen.

[Jccc]

Thank you all for the repleys. I tested the start capacitor with a multi meter and it seems to be working so that eliminates that problem.

I will see if i can have someone open up the motor and give it a good cleaning.

[Jccc]

So i got the motor cleaned and regreased and it works again! Now i got another problem!
Once i have the motor back in place and everything reassembled i go & switch the platter on to see if it spins and it does not!

I hear the motor spinning but for some reason its not making contact with the rubber pucks.
I go and make sure everything is in place and if im missing any parts but everything it seems to be all there. I even try bringing the motor closer and messing with different settings and its still not working.

This is driving me crazy right now. I must have spent 6 hours or so tweaking out adjusting everything i could & its still not working.

Has this happened to anyone else before?

[tragwag]

those rubber idler wheels sure are fickle at times.
It's never been that bad for me.
I would check the shaft of the motor that comes up to the wheels, I've taken that off once before to remove a 45rpm adapter.
It's an allen wrench adjustment.
Maybe it's not tight?

I wish I could take pictures to show you better, but I'm cutting atm.

[Steve E.]

There is a definite adjustment or two to make regarding the position of those wheels and maybe the motor or capstan itself (I am far from my 6N right now). Look in the 6N manual on this site, it should explain it. Can you reach under? try pulling and pushing the motor, see if that changes the contact.

[Steve E.]

One thing I have to say about the 6N, I love how well it seems to work --when it works-- by simply approximating. Motor? Yeah, get it over there, shove it kinda near the platter. Cutterhead? Yeah, get it somewhere between zero and five degrees, turn that little springy doohickey a couple times.

You can indeed spend hours, at times, getting it within those tolerances, but once you are there it's a little miraculous. Yours might have been operating just on the edge of the tolerances and it finally went out.

[Jccc]

Yes the 6n is a really excellent machine when it was running when i had it dialed in. I must have spent many hours cutting music until the motor went out.

Here is a picture of the inside where the switch turns on and is supposed to move the rubber pucks.
Does everything seem to be in the right place?

For some reason i got the motor to touch the rubber wheels but now they seem not to touch the inner part of the platter.

I noticed when i switch it on the part thats holding the rubber wheels is not fully turning to touch the motor shaft.

[markrob]

Hi,

Loosen the two outside screws on the motor mount. That will allow you to slide the whole assembly closer to the idler rollers. Also, make sure the rubber shock mounts are not rotted and that the motor hangs freely. Also check that the two long screws that pass through the rubber shock mounts are not bent. If so, they will affect the alignment of the motor to the idler wheels.

Mark

[emidisc]

Hey Jccc,

you mentioned you had just oiled and greased your machine so check you have not left any oil residue on the rubber idlers and mating surfaces etc this is easily done and will cause them to slip.

Emidisc

[Jccc]

Thank you all for the replies and help. I have checked the rubber pucks and there is no oil on them.

I did figure out why the idle wheels were not touching the motor shaft. I had the motor mount on backwards! So now everything sort of works again.

I am still having trouble with the motor starting up and sometime seizing while cutting. I know the start capacitors are ok because i did test on those and i put oil in the right areas.

I think there is still some hardened grease in there that is causing it to seize or properly start.

Im gonna look for the oil of wintergreen hopefully that will fix it.

[Jccc]

Well my motor seems to be about dead. I think? I changed the start capacitor and the run capacitor with brand new ones thinking it would help the motor. Failed

I even took the motor apart again and checked to see if anything was shorting out. failed

Basically when i try to switch it on i hear the motor humming (electric going to it) but i have to give the motor shaft a twist to get it going but then i cant put the platter on because the rubber pucks are in the way. so i have to turn it off. i which i have to keep repeating the same thing over and over again.

Some times i get lucky and it turns and i can get a few minutes of cutting in before the motor freezes up in the middle of a recording session.

Does anyone know where to get a brand new one for pretty cheap or guide me to a web site where i can buy one?

Any help will do.

[tragwag]

there is a thread somewhere here with the bodine link, or equivalent.
give the search feature a try!

[Jccc]

Well i did a search for a new motor and gave up & decided to take the old motor apart again.

Upon taking it apart i noticed the top bearing had seized up pretty good causing the motor shaft to get grinded up just a tad bit.
Maybe that was one of the reasons why it would just lock up in the middle of cutting.

I fixed that up by applying some new oil and a dab of grease and lightly sanding the shaft where it got grinded.

I also noticed that the motor shaft had a little play to it (where i could push and pull the shaft) and it had a slight click whenever i turned the motor shaft by hand.

So i added a small washer on the bottom of the shaft (kinda right under the fan part where the bottom washer is) to make it more tight.

I then gave it a test and did prolly around 30 minutes worth of cutting non stop and it worked!
I felt the motor and it was pretty hot so i gave it a break until it cooled down and then continued on again. It worked again!

So i guess i fixed the problem finally!

I still have to give the motor shaft a few turns before i turn it on to get the motor running but once its on, it will keep on going.

Hopefully thats the last of it!

[Angus McCarthy]

Awesome. Just make sure it's well-lubricated. The old beasts of a motor tend to run hot anyway. I've considered mounting a small fan in the case near the motor just to keep air circulating. That might help in this situation, too.