Wurlitzer 2410 turntable motor speed driving me crazy

Hi folks!
I believe I was signed up here at phonoland years ago, but have misplaced my login information. So here I am with a new account!

I have a really cool Wurlitzer 2410 that works great... has a rebuilt amp and power supply, selects and plays fine, looks great... but has a strange turntable problem.

When the box is first turned on, everything is fine and the records play at what sounds like the correct speed. When the box warms up after a few hours, the turntable speed increases. You can hear it in the selections, they play too fast, and it's pretty noticeable. I would guess maybe 5rpms too fast or so.

I've replaced the belt (today) and it still does it... I loosened the screw that adjusts the belt tension and made it as slack as possible, and it's still too fast. I put it on the other pulley (there's two on the motor, they look pretty much identical though) and that didn't change it... I looked at the schematics, and it appears that the motor runs off 120 volts straight off the ac line coming from the wall.... so there's no caps in the line or resistors that I can tell that could be changing value as they heat up.

Any ideas? I've heard these carousel turntables run slightly fast anyways, but it's fine when it's first turned on. Any help appreciated!

Hi Ronnie, welcome back.
My GUESS wold be, that when you think it's "running fine", it's actually slow. Almost all electric motors will slow down when cold--speed up when warm. That being said, put a strobe on it and see exactly what is happening. I suspect the motor could use a good dis-assembly, and cleaning, and then a large dose of 20 wt ND oil. As far as I know, there is no way to slow it down, because, as you state, it runs directly on line voltage. Ron Rich

Ron's got a point there.
Most older motors are "sluggish" when cold.
Much of this has to due with the old oil being thick and aged.
The best way to remedy it is to really dissasemble the motor, flush the bearings thoroughly with a solvent, including any oil-retaining pads.
Sintered bearings hold old oil, and I heat them carefully with a soldering iron to make the old oil "bubble out" then use solvent for the remaining stuff.
Once the pores of the bearings are emptied of old sludge, and any solvent dried out, I use the Zoom Spout Turbine Oil to replenish the bearings and wicks.
Usually is successful when done that way.
The motor shafts if sludged-up and not scored can be polished with 1000/2000 fine Emory paper.
Sure it's laborious! - but there's no shortcut to perfection.

There is a "fix" for the overspeed problem. It requires winding tape carefully in the flywheel pulley's trench to increase it's diameter.

You will need to use a thin tape and calendar it to fit within the trench pretty close to exactly. The best approach is to add too much tape and then remove turns till the speed is to your taste. This is the reverse of the old radio station trick when they wanted to speed up non-adjustable turntables.

Obviously, the motor's speed will have to be made consistent and that involves what Matt has mentioned. Sludged, glazed bearings are the first problem here.

I don't know why some manufacturers pitched up their machines to this extent. By far the worst are the Rowe/AMI 1100 series changers, but at least there careful grinding of the motor pulley will fix that.

Rob/NYC

Thanks for the advice folks. I'm leaning towards it being that they were simply fast from the factory, I've heard people mention that... and watching some youtube videos of carousel mechs many of them sound fast as well.

Not sure what direction I'm going to take it yet, as of now you can play it for well over an hour or two before it ever starts speeding up, so maybe gummed up is the way to go

I've done that tape trick before on I think a Rockola 490 that was too fast, I put it on the inside of the turntable, worked great! If I get the perfect width tape (looks like half inch or so) that should work out pretty good...

Oh yes, brings back radio tricks. It was a dirty game. The station I worked for did that to our transfer turntables. We put all our music on carts so the music was always pitched up. Anyone who listened to us got so used to pitched up music that if they listened to the competition the same music sounded like crap. Unfortunately it had the same effect if they bought the records. I agree with Ron. I would strobe it to find out where the issue is.
I bought a turntable for home that I never knew ran slightly fast. Later when variable speed tables arrived I bought one. I set it per the strobe and was like what the hell. Friends would come over and ask why my new turntable was running slow. Human perception is amazing.
Hey Ron Rich, if you are reading this I tried to PM you. Just curious if you got it. I may need your expertise when I start working on my 425. Let me know. Thanks.