FAQ What is the purpose of PSU Control Interface J902? PSU Control Interface J902 is used for onboard sensing of output supply voltage and power supply volume control.Are the speaker outputs of Loudspeaker Connectors J101J107 grounded? No, both positive and negative speaker outputs are floating and may not be connected to ground.How many pins does J902 have? PSU Control Interface J902 has 5 pins, each serving a specific function.