Vintage DD turntables. Are we living dangerously?


I have just acquired a 32 year old JVC/Victor TT-101 DD turntable after having its lesser brother, the TT-81 for the last year.
TT-101
This is one of the great DD designs made at a time when the giant Japanese electronics companies like Technics, Denon, JVC/Victor and Pioneer could pour millions of dollars into 'flagship' models to 'enhance' their lower range models which often sold in the millions.
Because of their complexity however.......if they malfunction.....parts are 'unobtanium'....and they often cannot be repaired.
128x128halcro
Hi Halcro,
I have a few more questions if you don't mind.
Acquired a TT-101 motor on ebay.
Arrived today and I unpacked it and was shocked:
At first glance it appeared DOA.
Without the platter installed, as you press 33 or 45, the spindle is making grinding noises and never gets to the proper speed (33.33 or 45). The LED display shows the motor is rising in speed to random numbers below the required speed and then the counter goes back to zero and re-starts again.
Putting the internal counter switch on "hold" gets this re-counting to stop but again, speed never gets to either 33.33 or 45.

When assembling the platter on the spindle, the bottom of the platter scrapes against the base underneath it and when pressing the 33 or 45 does not turn at all. On a closer look you can see that the platter is eithef not concentric with the base's outside diameter, is not sitting in the centre as if the spindle is bent or out of centre or sitting too low.

On an even a closer look yet, finally picked on what's wrong:
The spindle is a cone which enter an opposing cone in the platter's hole.
It seems that either the spindle cone "shrank" from its original size and/or the opposing concical hole in the platter "expanded" or the spindle sits too low to engage and support the platter above the base.
The size tolerance could have been a temperature issue (expansion and contraction).
End result is that the platter sits too low and scrapes against the base,
So? I took a skinny tape and put on the spindle cone (like a very thin shim) and guess what? The platter locks on the right speed, it rotates quietly and stops on a dime when I press the stop button,
So few questions:
1. The spindle seems to have axial freedom/clearance. In other words without the platter, when I gently pull the spindle it comes up a few thous. I have noticed this on my TT-71 motor too. I assume it is relying on gravity and the motor bearing is not a thrust bearing but not sure.
From your experience, is this slight axial freedom normal?
2. When trying to rotate the spindle without the platter it seems noisy and doesn't lock on 33.33 (it does on 45 but takes a while).
As soon as I put the platter on, its dead quiet and locks beautifully on both 33.33 and 45. Is this normal? Does your TT-101 functions similarly?
3. What's with the spindle cone/platter matching cone clearance?
Have you ever experienced such an issue?
Could it be a shipping damage (bumped on the floor and the spindle moved down from its original place, which would have resulted in the same exact result?

Any additional thoughts/advice would be most welcome!

Thanks and kind regards,

Doron
I would not recommend running without the platter,often will cause lots of issues with speed lock etc and possible damage.

As to the issues was the table shipped with the platter mounted?

From your description you may have damage to the
platter ie lost tolerance of the mating area due excessive
shock.
The scraping is yet to be determined likely related to what caused the platter deformation issue.

Not a great way to start your Victor experience.
Doron:

Platter height is adjustable via a screw at the bottom of the unit (where the bearing is). You'll have to take off the metal cover to access it. It is cemented into place per stock, but perhaps the previous owner messed with it. Scraping is likely due to the platter being too low. Mine was the same way. Perhaps the bearing oil ran out or up due to shipping, thus causing the platter to sink ever so slightly? You might wait a day or so to see if it self corrects before messing with the bearing screw.

As Totem said, don't run motor w/o platter. It's calibrated for a specific load, so it shouldn't lock speed w/o platter. I'm surprised to hear that it locked at 45 for you.
Fleib, On 8/29 or thereabouts you wrote, "Lew,
You mean 21mm short of the lead-out groove, which would be about 80mm from the spindle?" Then Hi-ho made some further comments to indicate that 76mm is correct.

But if you guys will look at the diagram in the article quoted by Hiho, follow the arc formed by the dotted line. In order to achieve zero tracking error (stylus tangent to groove) at point B, as defined by the designer of the RS-A1 in that diagram, the stylus needs to hit the label or the run-out grooves of the LP where that arc comes closest to the spindle, which I think is indeed about 21mm from the spindle. Thus we were talking about two different things, in one case how to mount the arm, in the other case, where on the LP playing surface we wish to achieve the one point of zero tracking error.

As to the Rigid Float. All that babble about how the "bearing" is constructed does not allow me to form a picture in my mind of how it works, how something can be both "rigid" and "floating". I would need to play with one to convince myself. Well Tempered liked to sell the idea that their tonearms have no bearing and hence no bearing friction; the problem is that their bearing (which IS a bearing, semantics notwithstanding) has a fair amount of play and so low friction is achieved at the expense of wobble.