Accessories; Before Repair; Protection Circuitry - Panasonic SC-AK48 Service Manual

1 Accessories

2 Before Repair

1. Turn off the power supply. Using a 10Ω, 10W resistor,
connect both ends of power supply capacitors (C571 - 574,
558) in order to discharge the voltage.
2. Before turning the power supply on, after completion of
repair, slowly apply the primary voltage by using a power
supply voltage controller to make sure that the consumed

3 Protection Circuitry

The protection circuitry may have operated if either of the
following conditions are noticed:
• No sound is heard when the power is switched ON.
• Sound stops during a performance.
The function of this circuitry is to prevent circuitry damage if, for
example, the positive and negative speaker connection wires
are "shorted", or if speaker systems with an impedance less
than the indicated rated impedance of the amplifier are used.
If this occurs, follow the procedure outlines below:
1. Switch OFF the power.
2. Determine the cause of the problem and correct it.
3. Switch ON the power once again.
Note:
When the protection circuitry functions, the unit will not
operate unless the power is first switched OFF and ON
again.
current at 50Hz in NO SIGNAL mode should be shown
below with respect to supply voltage 230/230-240V.
Power supply voltage AC230V, 50Hz
Consumed current Less than 250mA
3
SA-AK48
AC230 - 240V, 50Hz
Less than 250mA