The IC3600SCBD4A is a printed circuit board (PCB) which was produced by General Electric for the Mark I-Mark II system. The Mark I and Mark II were the earliest systems in the Speedtronic Mark turbine control series. The first Mark system, Mark I, was first installed in Long Island, NY as early as 1968.
The IC3600SCBD4A consists of two distinct parts. The main part of this board is a rectangular printed circuit board (PCB). A long line of large metal prongs takes up the right edge of the printed circuit board. These prongs help connect the circuit board to the rest of the Mark system. A few medium-sized resistors can be seen on the IC3600SCBD4A. These resistors are connected to metal cube-shaped metal parts with wires. Several yellow capacitors are also located on the surface of the IC3600SCBD4A. These capacitors are attached to the surface of the board with white wires. The several cube-shaped metal parts are arranged in lines on either side of the IC3600SCBD4A. These parts are used to wire the IS3600SCBD4A into the rest of the system. The other main part of the IC3600SCBD4A is a large metal plate which is attached to the side of the printed circuit board. This metal plate features two large dials at the top. The first dial is labeled with CURR which stands for current. The dial directly below it is labeled VOLT for voltage. There are four large switches underneath these dials. The upper two switches are identified by the word COM and the two lowest switches are labeled as VOLT which stands for voltage.