Panasonic SAHT280 - RECEIVER, Service Manual

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Fig.1
Fig.2
2. Before Repair and adjustment
Disconnect AC power, discharge Power Supply Capacitors C703, C704, C705 and C706 through a
10 , 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 AC120V, 60Hz in NO
SIGNAL mode should be 600-1000mA.
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. Accessories