Panasonic SA-XR55E, Service Manual, Page: 6 / 130

3 Before Repair and Adjustment
Disconnect AC power, discharge Power Supply Capacitors C707, C717, C718 and C924 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 230-240 V, 50 Hz in NO SIGNAL mode should be ~400 mA.
4 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.
5 Handling the Lead-free Solder
5.1. About lead free solder (PbF)
Distinction of PbF P.C.B.:
P.C.B.s (manufactured) using lead free solder will have a PbF stamp on the P.C.B.
Caution:
· Pb free solder has a higher melting point than standard solder; Typically the melting point is 50 - 70°F (30 - 40°C) higher. Please
use a high temperature soldering iron. In case of soldering iron with temperature control, please set it to 700 ± 20°F (370 ±
10°C).
· Pb free solder will tend to splash when heated too high (about 1100°F/600°C).
· When soldering or unsoldering, please completely remove all of the solder on the pins or solder area, and be sure to heat the
soldering points with the Pb free solder until it melts enough.
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SA-XR55E / SA-XR55EB / SA-XR55EG