RD-379 A(V) UNH BLOCK DIAGRAM The overall system block diagram of the RD-379 A(V)/UNH recorder/reproducter is divided into main sections. Transport no. I, Transport no. 2 and the common to both transport area which is located in the middle of the diagram between the two vertical dashed lines. The main signals are depicted from their origination points and are easily traceable to termination. The block diagram is the best drawing to use during system check out procedures in order to isolate malfunctions to the possible subassembly.