Panasonic SA-HT920P Service Manual page 7

4 Before Repair and Adjustment
(Using Active Subwoofer)
Disconnect AC power, discharge Power Supply Capacitors C546~C549 through a 10 Ω, 10 W resistor to ground.
DO NOT SHORT-CIRCUIT DIRECTLY (with a screwdriver blade, for instance), as this may destroy solid state devices.
After repairs are completed, restore power gradually using a variac, to avoid overcurrent.
Current consumption at AC 120 V, 60 Hz in NO SIGNAL mode should be ~ 1000 mA.