Panasonic SA-HT530EB, Руководство по обслуживанию

Страница: 9 / 152

- 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.
7. 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, which
should be removed for potential shock reasons prior to applying
power to the unit under test.
2. After removing an electrical assembly equiped with ES devices,
place the assembly on a conductive surface such as aluminium
foil, to prevent electrostatic charge build up or exposure of the
assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ES
devices.
4. Use only an anti-static solder remover device. Some solder
removal devices not classified as “anti-static (ESD protected)” can
generate electrical charge to damage ES devices.
5. Do not use freon-propelled chemicals. These can generate
electrical charges sufficient to damage ES devices.
9