
eachpoint.
5. Reverse theACplug intheACoutlet and repeat eachoftheabove
measurements.
6. Thepotential at anypointshouldnotexceed0.75 volts RMS. A
leakagecurrenttester(Simpson Model 229 orequivalent) maybe
usedtomake thehotchecks, leakagecurrentmust notexceed1/2
milliamp. Incase ameasurementisoutsideofthelimits specified,
thereisapossibilityofashock hazard, and theequipmentshould
berepairedand recheckedbeforeitisreturnedtothecustomer.
2. Handling the Lead-free Solder
2.1. Aboutleadfree solder(PbF)
Distinction ofPbF P.C.B. :
P.C.B.s(manufactured)using leadfree solderwill have aPbF stampon theP.C.B.
Caution:
-Pbfree solderhas ahighermelting pointthat standardsolder;
Typicallythemelting pointis50 -70°F(30 -40°C)higher. / Please
use ahigh temperaturesoldering iron. Incase ofthesoldering iron
withtemperaturecontrol, please set itto700 ±20°F(370 ±10°C).
-Pbfree solderwill tend tosplashwhenheatedtoo high (about
1100°F/600°C).
-Whensoldering orunsoldering, please completelyremoveall ofthe
solderon thepinsorsolderarea, and besuretoheat thesoldering
points withthePbfree solderuntil itmelts enough.
3. BeforeRepairand Adjustment
DisconnectACpower, dischargePowerSupplyCapacitorsC546, C547, C548, C549 through a10
, 1Wresistor toground.
DONOTSHORT-CIRCUITDIRECTLY(withascrewdriverblade, for instance), as thismay destroy
solidstatedevices.
Afterrepairsarecompleted, restorepowergraduallyusing avariac, toavoidovercurrent.
Currentconsumption atAC230-240V, 50HzinNOSIGNALmodeshouldbe~500 mA.
4. Protection Circuitry
Theprotection circuitrymay have operatedifeitherofthefollowing conditionsarenoticed:
-Nosound isheardwhenthepoweristurnedon.
-Sound stopsduring aperformance.
Thefunction ofthiscircuitryistopreventcircuitrydamageif, for example, thepositive and
negative speakerconnection wires are
“shorted”, or ifspeakersystemswithanimpedance less thantheindicatedratedimpedance of
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