Technics SL-J2 platter: a compartment? What's for?

[catBot]

Hello!

Technics SL-J2 here.
Right under the mat on the platter there is a comtartment near the spindle as if some electronic module to be placed there.
What could that be?

 

[felix_katze]

There should probably be a lever to detect that a record is on the platter, which activates a switch below, and there'd be a second lever detector off to side that detects if it is a 33/13 or 45 size record. This is so it knows where to drop the needle.

Yours may just be missing.

 

[Powertech]

When a major high volume manufacturer produces a range of models some components are shared between them. Like a range of cars, they make the most complex version first and then start removing bits for the lesser models in the range. Main wiring looms etc are all the same - with some plugs and sockets left unused for the lower models. The same applies here.

Example - I have a Sansui Sr-D36 turntable which is direct drive. It uses the same platter as the Sr-D25 which is belt drive. It's more efficient (and cheaper) to produce a single platter that will suit multiple turntable models than it is to to produce specific parts for each unit.

 

[lini]

(...) Yours may just be missing. (...)

(...) with some plugs and sockets left unused for the lower models. The same applies here. (...)

I don't think so (regarding the "may just be missing") - or respectively in this case rather the opposite, one could say (regarding the "left unused for the lower models").

Shall mean., while I agree, that this compartment is intended for a record detection sensor, I'd deem it likely, that this sensor is only required for models, that do not sport a track detection (and arm position) sensor, as the latter would make the former superfluous.

Greetings from Munich!

Manfred / lini

 

[Beobloke]

As others have said, that cutout is for the mechanical size detector used on cheaper models.

The SL-J2 obviously shares its platter with these but doesn’t need the size selector as it does this electronically.

SL-J110R platter picture showing the gadgetry below. It’s not exactly the same platter but the concept is similar.