Tiger River Hot Springs Electronic Heater PCB Board PC - 74618 77119 Part Number: 74618 This is a Tiger River and Hot Springs Electronic PC Board 74618 or 34923. The size of the board is 5"x 5". Includes the updated IQ2020 Heater Relay board with jumpers and screws to secure to font cover of the IQ2020. Hot Spring Spa Supplies carries spa fragrances, air & water valves, control systems, filter accessories, lights, cleaners, pumps, thermostats, and more for virtually every hot spring model.