Classic belt-drive turntable and successor of the famed TD-124, a very different successor and not nearly as sought after.
The TD-125 was originally offered with the TP-14 tonearm and TP-50 headshell, changed to TP-25 with the TD-125II (still with the TP-50) and sans tonearm for the large and very elegant TD-125LB version.
Speed on all three versions is generated by an AC generator, the frequency of which is set by a Wienbrücke (Wien bridge) made with stable resistors and capacitors.
Some versions have an EMT transformer, some not : the TD-125 was "made in West Germany under Swiss licence".
The synchronous motor itself has 16 poles and can run between 175rpm and 350rpm. Speed changes are performed by altering the bridge's output frequency : 16rpm, 33 1/3rpm and 45rpm plus manual pitch if desired, within ± 2% and with stroboscope help.
Supension is traditional Thorens : a 7kg diecast base supporting the platter and the tonearm's base makes one layer, and a fixed chassis with the motor and electronic boards makes the other.
If not placed on a very stable and even support, this system really has a tendency to wowiezowie back and forth but if you're not disco dancing next to it, it works.
Classic Thorens again : the platter is a 30cm dynamically balanced non-magnetic zinc alloy weighing 3,2kg ; the sub-platter is made of the same material - classic Thorens.
Japan saw a last hybrid version in 1975 : TD-125IIAB, a regular TD-125II with the more modern TP-16 tonearm.
Ulimately replaced by the TD-126 series which was very successful in Japan as well in many versions and with many japanese "ultra" options just for the... japanese.
Properly setup (properly setup), a TD-125 works, makes music and lasts forever : no crazy ICs, no electronic damping, no fiddly programmation modes.