Teres turntable motor problems

Hi,  thanks for the response.  I built my table base, so i will be comfortable machining it a bit if need be.  I think from looking as the Sota info, that the magnet should fit though.  I have a 12.25" dia platter and the Sota's are different.  Do you know how the magnet (on the platter) placement is accounted for?  Do you just adjust on the "box".  I guess i am confused as how 33.33rpm, etc is nailed down, if the magnet is just placed.  i understand once it is nailed down that drift/variance will be shown.  Hope that is clear, thanks

In the Phoenix Engineering set-up, the sensor is set in a fixed position under the outer edge of the circle described on the surface of the plinth by the platter floating above it. Then a magnet is fixed to the underside of the platter, at its outermost edge, such that the two elements pass over each other with each complete rotation of the platter, with a certain max tolerance for the distance between them when they are momentarily superimposed. Every time the two elements are in proximity, a signal is sent to the Roadrunner (tachometer), where the speed of the platter is compared to a reference (33.333 or 45.000, depending on the setting). If the Roadrunner perceives the platter is moving a hair too slow, it sends out a signal to the voltage source (I forget the Phoenix Eng names for that device; they made two versions with different wattage ratings, so the original PE system is compatible with a wide variety of AC synch motors), which pulses the motor to speed up if that is needed. Or the motor reduces the drive force, to slow down the platter. The Roadrunner is not just monitoring speed; it is actively maintaining an exact set speed via its role in feedback to the driving amplifier. I hope this answers your question. In the Sota system, the driver amplifier is designed specifically to work with their Eclipse motor that is included in the Eclipse package.

i think the light bulb went on, my head was confusing speed and RPM. 

i think my big decision now is do i fork out about $1700 (sota=1500 + taxes,+ shipping+ new belt + new pulley) for this, or do i just go buy a used VPI or something for about $2k and sell my existing bits/arm off.  thanks for the help.

Not sure why you are giving up on your present motor unless you found out fixing it was prohibitively expensive, but the gains associated with tight speed control afforded by the SOTA Eclipse system are not trivial. In other words you’re not just getting a new motor. Whereas a used VPI also “needs” the Eclipse.

My current motor is no longer manufactured and the builder has gone out of business.  i am doing trouble shooting/tweaking of what i have now and also feeling out what my options may be.  The Sota does sound very nice and seems like it could easily install it on my own, so very tempted if i do need to go that direction