TrolMaster 24V Control Board (OA6-24)TROLMASTER 24V CONTROL BOARD (OA6 24) The OA6 24 control board is designed to control multiple 24vac solenoid valves. It provides an easy and efficient method to control up to 6 valves, each with individual timer settings. Up to 5 OA6 24 can be connected to a single Aqua x providing a maximum of 30 individually controlled outputs to connect to your solenoid valves. The Aqua x can also provide a master pump link by using a DSP 1 along with the OA6 24.