measurements.
6. Thepotential at anypointshouldnotexceed0.75 volts RMS. A
leakagecurrenttester(Simpson Model 229 or equivalent) maybe
usedtomake thehotchecks, leakagecurrentmust notexceed1/
2milliamp. Incase ameasurementisoutsideofthelimits
specified, thereisapossibilityofashock hazard, and the
equipmentshouldberepairedand recheckedbeforeitisreturned
tothecustomer.
2. Handling the Lead-free Solder
2.1. Aboutleadfree solder(PbF)
Distinction of PbF P.C.B. :
P.C.B.s (manufactured) using leadfree solderwill have a PbF stamp on the P.C.B.
Caution:
-Pbfree solderhas ahighermelting pointthat standard solder;
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 or unsoldering, please completelyremoveall of
thesolderon thepinsor solderarea, and besuretoheat the
soldering points withthePbfree solderuntil itmelts enough.
3. Before Repairand Adjustment
DisconnectAC power, discharge PowerSupplyCapacitors C546, C547, C548, C549 through a
10 , 1 Wresistorto ground.
DONOTSHORT-CIRCUITDIRECTLY(with a screwdriverblade, forinstance), as this may
destroysolidstate devices.
Afterrepairs are completed, restore powergraduallyusing a variac, to avoidovercurrent.
Current consumption atAC 230~240V, 50HzinNOSIGNALmode shouldbe ~400 mA.
4. Protection Circuitry
The protection circuitrymayhave operatedifeitherof the following conditions are noticed:
-Nosound isheard whenthepoweristurnedon.
-Sound stopsduring aperformance.
The function of this circuitryis to prevent circuitrydamage if, forexample, the positive and
negative speakerconnection wires are
“shorted”, orifspeakersystems with animpedance less thanthe indicatedratedimpedance of
the amplifierare used.
