The System 500 may never have even been productized.  I have never seen one offered on eBay since my first searches in 2012 and there are no known photos of it. The actual subject matter was not revealed in the (known) price lists until March 1st, 1982 when the System 500 (the complete self-contained version of the Ausbausystem 5) was listed for the first time.  

The curriculum was Logik und Leistungselekronik incl. Lectron Motor (logic and power electronics including motor).  The Triac, Diac, Unijunktion Transistor, Leistungstransistor npn, and Leistungsdiode blocks were featured blocks in this model. This curriculum was also added to the Labor Spezial SK III model.