Panasonic SA-HT535EE Service Manual

- 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 andnegative speaker connection wires are“shorted”, or if speaker systems with an impedance less than the indicated rated impedance ofthe 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 turnedoff and then on again.6. Prevention of Electro Static Discharge (ESD) toElectrostatically Sensitive (ES) DevicesSome semiconductor (solid state) devices can be damaged easily by electricity. Suchcomponents commonly are called Electrostatically Sensitive (ES) Devices. Examples of typicalES devices are integrated circuits and some field-effect transistors and semiconductor “chip”components. The following techniques should be used to help reduce the incidence ofcomponent damage caused by electro static discharge (ESD).1. Immediately before handling any semiconductor component orsemiconductor-equiped assembly, drain off any ESD on yourbody by touching a known earth ground. Alternatively, obtain andwear a commercially available discharging ESD wrist strap, whichshould be removed for potential shock reasons prior to applyingpower to the unit under test.2. After removing an electrical assembly equiped with ES devices,place the assembly on a conductive surface such as aluminiumfoil, to prevent electrostatic charge build up or exposure of theassembly.3. Use only a grounded-tip soldering iron to solder or unsolder ESdevices.4. Use only an anti-static solder remover device. Some solderremoval 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 generateelectrical charges sufficient to damage ES devices.8PDF created with pdfFactory Pro trial version www.pdffactory.com