Problem: Power indicating LED (DS1) on SBRII circuit board is not lit, indicating no power.
Solution: Check incoming 115VAC power supply to the SBRII. Verify circuit breakers, fuse F1 in electronics compartment, and all power connections are tight. Ensure power transformer connections are secure at J1 (115VAC) and J2 (16VAC). Check that power wires are connected according to SBRII wire diagram.