-Nosound isheardwhenthepoweristurnedon.
-Sound stopsduring aperformance.
Thefunction ofthiscircuitryistopreventcircuitrydamageif, for example, thepositive and
negative speakerconnection wires are
“shorted”, or ifspeakersystemswithanimpedance less thantheindicatedratedimpedance of
theamplifierareused.
Ifthisoccurs, followtheprocedureoutlines below:
1. Turnoff thepower.
2. Determinethecause oftheproblemand correct it.
3. Turnon thepoweronce againafteroneminute.
Note:
Whentheprotection circuitryfunctions, theunitwill notoperateunless thepowerisfirstturned
off and thenon again.
4. Prevention of ElectroStaticDischarge (ESD) to
ElectrostaticallySensitive(ES) Devices
Somesemiconductor (solidstate)devices canbedamagedeasilybyelectricity. Such
componentscommonlyarecalledElectrostaticallySensitive (ES)Devices. Examples oftypical
ES devices areintegratedcircuitsand somefield-effecttransistorsand semiconductor “chip”
components. Thefollowing techniques shouldbeusedtohelpreduce theincidence of
componentdamagecausedbyelectro staticdischarge(ESD).
1. Immediatelybeforehandling anysemiconductorcomponentor
semiconductor-equipedassembly, drainoff anyESDon yourbody
bytouching aknownearthground. Alternatively, obtainand wear
acommerciallyavailabledischarging ESDwrist strap, which
shouldberemovedforpotential shock reasonspriortoapplying
powertotheunitundertest.
2. Afterremoving anelectrical assemblyequipedwithES devices,
place theassemblyon aconductivesurface suchas aluminium
foil, topreventelectrostaticchargebuildup orexposureofthe
assembly.
3. Use onlyagrounded-tipsoldering iron tosolderorunsolderES
devices.
4. Use onlyananti-staticsolderremoverdevice. Somesolder
removal devices notclassifiedas “anti-static(ESDprotected)”can
generate electrical chargetodamageES devices.
5. Donotuse freon-propelledchemicals. These cangenerate
electrical charges sufficienttodamageES devices.
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