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- 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. Safety Precautions
5.1. 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.
5.1.1. 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 1M and 5.2M .
When the exposed metal does not have a return path to the
chassis, the reading must be
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.
Figure 1
6
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