Lyric/Neumann users, have you had flutter problems?

[smithadamm]

im having some flutter problems with my setup. It is a Neumann turntable bearing with a lyric motor. If I play the 3150hz tone on my test record, it will get up to 3160 and down to 3140 or so. You've really got to strain to hear it, but it is there. Coupling shaft between the motor and TT is straight and straight up and down. The turntable isn't eccentric, I checked and rechecked that. I also tried changing out the oil in the bearing with 600w gear oil. The top and bottom of the bearing move freely against each other when the TT isn't installed, once the 70lb TT is loaded up, I can't really get it to move in relation to the bottom of the bearing. I'm not sure if this is normal or not. Have any Neumann bearing/lyric motor users run into this? If so how did you solve it?

[concretecowboy71]

Is it possible the that the large cap that is attached to the motor is bad?

I am not strong with my electronics, but that seems like the only thing in your system that you did not mention.

I am sure others with better knowledge than me can explain what that cap does, but I did have to replace one exactly like it on a jukebox that was having speed issues.

I know one of the caps on the motor drives the start motor function and the other helps keep the motor stable. Please correct me if I am wrong.

[gold]

Have you double checked the frequency measurements with a frequency counter? I'd make sure there was actually a problem first. What you are describing could be an aural illusion.

[mossboss]

Seriously that's well within the tolerance of any mains frequency based motor
It is less than 1% say 0.6-7% which is quite reasonable
The mains frequency that the motor depends upon for its speed will most likely be the cause assuming it is fluttering for no other reason like coupling
Get an accurate freq meter place it on the supply line than do your test again after establishing that you are getting exact 60 hZ out of the mains supply line I would be surprised if it is the case you are getting exact 60 hZ
Don't be surprised, as you will most likely find the line fluctuates, most likely within that range of a similar percentage
It is now getting to be a pain as any one feeding the grid with surplus power sourced via solar collectors or some other means have to " push" it to the mains at a slightly higher frequency in return you will get fluctuations all the way down from the step down transformer to the supply point which may be a few blocks down
On another note
There is only one start capacitor installed on any Lyrec motor on a VMS, only for starting which in my experience never seems to do the trick
I have yet to see a run capacitor as well as a start one.
May be i am missing something but the schematics clearly show only one cap
Cheers
Best
C.

[Greg Reierson]

The run cap is mounted up inside the cabinet near the autoformer. It's in all of the schematics. We had a thread about it last year some time. It presents a phase delay to the second set of windings in the motor. The only time one would not be present is if the system were being driven from two legs of a three phase power system.

I doubt it's causing speed issue but I suppose it's possible.

To eliminate the motor, disconnect the shaft and give it a good spin while playing back the 3150 tone (with the power OFF. NEVER run the motor without a load). You should get a very stable drop in frequency as it spings to. If not then you may have a mechanical issue in the dashpot / platter assembly.

The speed error you describe is wow, not flutter. It would take some pretty bad bearings to induce flutter in a system with that much mass. What does your strobe show when it's spinning at speed?

[Greg Reierson]

If you do find a frequency fluctuation in the line, a ferror-resonant transformer may be abe to stabalize the frequency.

[Stevie342000]

[quote="mossboss"]Seriously that's well within the tolerance of any mains frequency based motor
It is less than 1% say 0.6-7% which is quite reasonable
quote]

The RIAA standard for 1954 states that allowable speed of variation for 50c/s supplies is +- 0.5%, I have no reference to any later standards. So from what I see it is roughly within tolerance, which given the age of the equipment and usage is not bad at all.

[mossboss]

I really like to know how any ferro whatever transformer would be able to stabilise frequency
Since frequency is established by gen set revolutions I just do no see how it would help in any way
If I am missing something please educate me
Thanks
Cheers

[markrob]

I really like to know how any ferro whatever transformer would be able to stabilise frequency
Since frequency is established by gen set revolutions I just do no see how it would help in any way
If I am missing something please educate me
Thanks
Cheers

Hi Chris,

I believe you are correct. They only stabilize against voltage variations, not frequency.

I'm not sure about the short term accuracy of the power line frequency, but they maintain extreme long term accuracy by insuring that the number of cycles in a 24 hour period is correct. If they did not do, this, clocks with synchronous motors would drift.

Using a Sola would help if the problem is dirty power rather than off frequency. In this case the transformer will cleanup the line noise and even fill in for short dropouts. Maybe that is the effect you are seeing.

MARK

[Greg Reierson]

Yes, that's right. I mispoke. A ferro will maintain a stable output level at it's resonant frequency during a brief loss or gap but not stabalize the frequency of what's coming in. Sorry.

[gold]

I logged line frequency one day for about 10 hours with my Fluke 287. It varied by 10ths of a hertz.

[smithadamm]

Thanks for all of the advice guys. I ended up fixing a few things, and that seemed to sort the problem out.

First, the hole in the "crown" coupling at the top of the lyrec was chewed up, so it had become eccentric. I had a local machine shop re-machine the shaft and coupling, the machinist went as far as to put a keyway in and add two set screws, so much more stable than the single set screw I was working with. I recommend anyone have that done to their motor. Wasn't terribly expensive, however, I had to take the non-working start motor off so the guy could get down to non-scarred up motor shaft. I also had them check my motor bearings, and those checked out fine.

Second, the upper TT bearing that sits in the oil had been worn down over the years and was letting the oil filled assembly seize sometimes, so it couldn't damp out irregularities. It wasn't an expensive bearing, but kind of hard to find. UBC Part # GT-7- if anyone ever needs to track one down.

Finally, my coupling shaft was a little out of true, either from the out of whack coupling, or maybe it just got a little bent getting moved in it's life. Anyway, I stuck a new one in and it seems like I'm back in business.

thanks again for all of the help.

[opcode66]

Fantastic post. Thanks for sharing this information!

[opcode66]

I've followed the advice of Greg Rierson from this thread http://lathetrolls.com/viewtopic.php?f=1&t=4844&p=36828#p36828 and have greatly stabilized the speed of my motor. My resulting Groove Graphic cuts are coming out much better. Still not as perfect as when cut with a digitally controlled platter motor. But, much better than what they were. Upon moving to L.A. I have found that my Lyrec was running much worse than it did in Chicago.

I did also check that the physical linkage was correct as is documented in this thread.

I'm working on a video detailing everything that I did. I will post it soon.

[smithadamm]

I had 8 months of operation with no problems on the lyrec/neumann bearing setup, then suddenly this week, I'm getting a huge amount of wow. Audible at 1k playing from my test record and on the scope you can see the waveform compressing and expanding with the change in pitch in the test tone. I've been through every inch of this drive train except the guts of the lyrec. Checked and rechecked the run cap, current draw, phase shift, turntable eccentricities. All fine. There is a little play in lyrec motor shaft, so I'm fearing the motor bearings have went. Has anyone opened heir lyrec up and changed the bearings? If so, how's you do it, how'd it go? Also, does anyone have a picture of the coupling between the drive shaft and the bottom of the TT bearing on their Neumann/lyrec or Scully/ Lyrec rig? Mine looks like it might be a homemade contraption.

[studiorp]

Sorry for question, but are there ic on your boards ?

This problem remember a little the same on a Revox A77 that I had in service . The direct drive capstan had a problem of wow and flutter, so the speed wasn't stable.

[studiorp]

Have you too tantalum caps on your boards?

If yes, check good every component. Unfortunately they are "famous" for give problems...

[smithadamm]

Sorry for question, but are there ic on your boards ?

This problem remember a little the same on a Revox A77 that I had in service . The direct drive capstan had a problem of wow and flutter, so the speed wasn't stable.

Thanks for the input. There aren't boards involved at all. They lyrecs are big synchronous motors that just need AC and a run cap if they are set to run on 2 phase power. The electronics are all doing what they should be doing, I'm just asking specifically if anyone has ever replaced the bearings on their lyrec motors and if those who have can give me any pro tips. I've replaced the bearings on synchronous motors before, specifically on ampex 440 tape decks, but this is one of those if I break this motor, I'm out of business type of problems so I'm gathering as much information as I can before I plow ahead.

[gold]

If you have the right bearing pullers and have experience with bearings it shouldn't be too difficult. Did you check the run cap? I think I have a exploded view diagram somwhere.

[gold]

If you are in the NY area Chris Muth has all the right stuff. Please don't ask him for any information unless you are hiring him.