JVC JR-S150 Service Manual

PrecautionsWhen the following parts are replaced, idling current adjustment is required.1.2.PoweranddrivertransistorsX705throughX716.ResistorsR721through R742.Note:Idlingcurrentisobtainedby measuringthevoltageoftheemitterresistorconnectedtothepowertransistor.Forthispurpose,checkpoints,Tab.No.709(710)and 713(714),arelocatedonTAP-268P.C.Board.Adjusttheresistor(s)ofleftandrightchannelsfor5to20mVfollowingthestepsbelow.Procedures1,BesurethatthefollowingresistorsareconnectedtoTAP-268P.C.BoardAss’yasshowninFig.22.Item No.:Value|R729(R730):6802R731(R732): 1.8kQ2|R727 (R728): 330 QPart Number | ORD141J-331 QRD141J-681 ORD141J-182 |Ifone(ormore)is(are)disconnectedatthefactory,connectresistor(s)havingthesamevalueasspecifiedabove.2.ConnectGNDleadwireofDCVTVMtoTabNo.709(710)andtheotherleadwiretoTab.No.713(714).Referto Fig.23.CPrecaution:Allowthesettowarmupatleast2minutesbeforeconnectingDCVTVM.=3.Readthepointer positionofDCVTVMandfollowtheprocedureslistedbelow.'f the DC VTVM pointerPosition indicates+e———_____Channel(L or R)OmV —2mV2.1 mV —5mvV5.1 mV — 20 mVOver 21 mVLeftLeft & RightLeftRightProceduresDisconnectR729 &R731(680Q&1.8kQ).DisconnectR730 &R732(680Q&1.8kQ).DisconnectR729(680Q).Disconnect R730 (680 2) .Proper idling current range.ReplaceR729(6802) bya330Qresistor.ReplaceR730(6809)bya3302resistor.Repeatprocedures2 and3JR-S150No. 2417 =