Before Use; Before Repair And Adjustment; Protection Circuitry; Safety Precautions - Panasonic SA-VK91DGCS Service Manual

SA-VK91DGCS / SA-VK91DGCP

1 Before Use

Be sure to disconnect the mains cord before adjusting the voltage selector.
Use a minus(-) screwdriver to set the voltage selector (on the rear panel) to the voltage setting for the area in which the unit will
be used. (If the power supply in your area is 117V or 120V, set to the "127V" position.)
Note that this unit will be seriously damaged if this setting is not made correctly. (There is no voltage selector for some countries,
the correct voltage is already set.)

2 Before Repair and Adjustment

Disconnect AC power, discharge Power Supply Capacitors C5815~C5818, C5829~C5830, C5835~C5836 and C5841 through a
10Ω, 5W 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 110/127/220~230V, 50/60 Hz in NO SIGNAL at (vol. min, in CD mode) should be as below:

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 turned 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. Turn off the power.
2. Determine the cause of the problem and correct it.
3. Turn on the power once again after one minute.
Note :
When the protection circuitry functions, the unit will not operate unless the power is first turned off and then on again.

4 Safety Precautions

4.1.

General Guidelines

1. When servicing, observe the original lead dress. If a short circuit is found, replace all parts which have been overheated or
damaged by the short circuit.
2. After servicing, see to it that all the protective devices such as insulation barriers, insulation papers shields are properly
installed.
3. After servicing, make the following leakage current checks to prevent the customer from being exposed to shock hazards.
4.1.1. Leakage Current Cold Check
1. Unplug the AC cord and connect a jumper between the two prongs on the plug.
2. Measure the resistance value, with an ohmmeter, between the jumpered AC plug and each exposed metallic cabinet part on
the equipment such as screwheads, connectors, control shafts, etc. When the exposed metallic part has a return path to the
chassis, the reading should be between 1MΩ and 5.2MΩ.
When the exposed metal does not have a return path to the chassis, the reading must be ･.
AC 50/60Hz 110 V
127 V
220-230 V
240 V
~ 1200 mA
~ 1100 mA
~ 700 mA
~ 650 mA
4