Panasonic SA-AK450PL, Service Manual

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1.3. 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.
1.4. Caution For Fuse Replacement
1.5. Safety Part Information
Safety Parts List:
There are special components used in this equipment which are important for safety.
These parts are marked by
in the Schematic Diagrams & Replacement Parts List. It is essential that these critical parts should
be replaced with manufacturer’s specified parts to prevent shock, fire or other hazards. Do not modify the original design without
permission of manufacturer.
Table 1
Reference No. Part No. Part name & Description Remarks
L5950 ELF15N035AN LINE FILTER
T5950 G4CYAYY00147 MAIN TRANSFORMER
T5951 G4C2AAJ00005 SUB TRANSFORMER
Z5950 ERZV10V511CS ZENER
RL5950 K6B1AEA00015 POWER RELAY
F1 K5D402APA008 FUSE
FP5920 K5G702A00009 FUSE PROTECTOR
FP5940 K5G702Z00004 FUSE PROTECTOR
FP5950 K5G402A00025 FUSE PROTECTOR
JK5950 K2AB2B000007 JK AC INLET
A2 K2CB2CB00018 AC CORD
R5950 ERC12UGK335D 3.3M 1/2W
2 Prevention of Electro Static Discharge (ESD) to
Electrostatically Sensitive (ES) Devices
Some semiconductor (solid state) devices can be damaged easily by electricity. Such components commonly are called
Electrostatically Sensitive (ES) Devices. Examples of typical ES devices are integrated circuits and some field-effect transistors and
semiconductor “chip” components. The following techniques should be used to help reduce the incidence of component damage
caused by electro static discharge (ESD).
1. Immediately before handling any semiconductor component or semiconductor-equiped assembly, drain off any ESD on your
body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging ESD wrist strap,
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SA-AK450PL