Read Panasonic SA-VK82DGN (serv.man2) Service Manual online
1 Before Repair and Adjustment
Disconnect AC power, discharge Power Supply Capacitors C5815, C5818, C9513, C9533, C9534, C9816 and C9817 through a
10
10
Ω, 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 220-240V at 50Hz in NO SIGNAL (vol. min, at CD mode) should be ~500mA .
After repairs are completed, restore power gradually using a variac, to avoid overcurrent.
Current consumption at AC 220-240V at 50Hz in NO SIGNAL (vol. min, at CD mode) should be ~500mA .
2 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.
· 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.
3 Safety Precautions
3.1. 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.
3.1.1. 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
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 1M
chassis, the reading should be between 1M
Ω and 5.2MΩ.
When the exposed metal does not have a return path to the chassis, the reading must be
.
Figure 1
3.1.2. Leakage Current Hot Check
(See Figure 1)
1. Plug the AC cord directly into the AC outlet. Do not use an isolation transformer for this check.
2. Connect a 1.5k
2. Connect a 1.5k
Ω, 10 watts resistor, in parallel with a 0.15µF capacitor, between each exposed metallic part on the set and a
good earth ground such as a water pipe, as shown in Figure 1.
4
SA-VK82DGN
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