Olympus BH-2 BHT - Power Transistor Replacement; AC Inlet Jack Replacement

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OlympusBH‐2(BHT/BHTU)Electronics   Revision2    Page14of24
PowerTransistor
PowertransistorQ101isaToshiba2SD867NPNpowertransistorintheoldTO‐3metalpackage(seeFigure15).This
part,althoughobsolete, can still occasionallybefound,butexpecttopay$20ormorefor it when you find it.If the
2SD867cannotbefound,thispart
canbereplacedwiththeSTMicroelectronicsBUX10part,whichisthesamepackage
styleandisalsoobsolete.TheNTE36partintheTO‐3PinsulatedcaseisagoodsubstitutethatisavailablefromAllied
ElectronicsandfromAmazon.
Whichever approach is taken, the replacement transistor must be installed using
 suitable mounting hardware which
provideselectricalisolationofthecollectortabfromtheequipmentchassis,andthermalpaste mustbeusedonboth
sidesoftheinsulatortoenhancethermalconduction.Ifnoneofthepartslistedabovecanbefound, lookforanNPN
partwithacollectorcurrent
ratingofatleast15A,acollector‐to‐emittervoltageratingofatleast100V,andacurrent
gainofatleast40,inasuitablepowerpackage.
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Figure15‐PowerTransistorMountedtoBHT/BHTUElectricalBase(100/115VVersion)
ACInletJack
Forsafety,alwaysreplacetheACinletjackwithanequivalentpart,whenavailable(seeFigure16).Makesurethatthe
chassis‐bondingscrewfortheground(middle)terminalofthejackispresentandsecureandthatthegroundingwireis 
undamagedbeforeoperatingtheequipment.Thisconnectionkeeps
thechassisatasafepotentialintheeventofany
electricalfaultswithintheequipment.
Ifasuitablereplacementjackcannotbelocated,afillerplatecouldbefabricatedtotaketheplaceoftheAC inletjack,
with a suitable hole drilled to allow an AC line cord to
 be installed with a strain‐relief grommet.If this approach is
chosen,besureto securely bond the ground conductorofthepowercord tothe unitchassisto maintain equipment
safety.