NAD-T163-pre-tb3 维修电路原理图.pdf

PAGE 1 OF 5Technical BulletinT163Product: A/V Tuner PreamplifierHardware Technical Bulletin: T163-H2004-03Date:August 24/04Subject:Residual NoiseNote:Implemented in production from Serial number :R47T1630186Previous T.B.s required: Please refer to the following software bulletin to perform thesoftware upgrade procedure.K K K KYEST163-S2004-01 Software Upgrade ProcedureK K K KNODESCRIPTION: At high volume setting with no signal on an unterminated analogue input,there maybe some audiable residual hum noise and whistling sound coming form one or morechannels.REASON:The residual noise is coming from power supply ground and DSP ground. Thewhistle noise is coming from the DSP board.SOLUTION: Remove the DSP board and order the replacement DSP board from our sparesdepartment . This board will require version 2.03 software or later,check for current versionon our service website, http:/ . Also see above for software bulletinfor the software upgrade procedure. Order the part number for the DSP board using thisnumber, 80-0907630-65-00 from our spares department. This board has Dolby Pro LogicIIxinstalled. NOTE: The HDCD decoder is replaced by the Dolby PLIIx decoder.Ground Changes1. Change the cable between J617 on Pre-out board and Multi-channel RCA from AWG22 to AWG18.Figure1Contact:NAD Electronics International633 Granite CourtPickering, ON Canada L1K 3K1Voice: 905-831-0799 FAX 905-837-Note: If this is not present onthe unit, add an AWG18 wirebetween the Pre-out RCA andMulti-channel RCA jacks asshown.RadioFans.CN 收音机爱 好者资料库PAGE 2 OF 5Technical BulletinT163Product: A/V Tuner PreamplifierHardware Technical Bulletin: T163-H2004-03Ground Changes2. The jumper wire between G2A on MAIN board and G2B on AUDIO IN board , remove the endconnected to G2B on the AUDIO IN board and connect this end to the chassis GROUND LUG. Seefigure2.Figure 23. For J705B and J704B on AUDIO PCB , cut all the AGND pins. That is pins 4,5,7 and 9 .on both J704Band J705B. See arrows in figure 3. NOTE: We suggest using the following slim line side cutters to allowfor easy cutting of pins.Consult your local supplier. See Figure 3A.Figure 3 Figure 3ARadioFans.CN 收音机爱 好者资料库PAGE 3 OF 5Technical BulletinT163Product: A/V Tuner PreamplifierHardware Technical Bulletin: T163-H2004-03Ground Changes4. Add a jumper wire between J8(copper bar) on main board and chassis. See figure 4.Figure 45. Install an AWG18 wire from the DSP board to the MULTI-CH. RCA connector ground. See Figure 5Figure 5PAGE 4 OF 5Technical BulletinT163Product: A/V Tuner PreamplifierHardware Technical Bulletin: T163-H2004-03DSP changes2. When installing the new DSP board perform the following. Float the DSP AGND (including thegrounding bracket or remove it) from the chassis using an insulated washer. See figure 6 ,7 and 8.Figure 6 New DSP board (indicated by yellow dot)Figure 7Contact:NAD Electronics International633 Granite CourtPickering, ON Canada L1K 3K1Voice: 905-831-0799 FAX 905-837-PAGE 5 OF 5Technical BulletinT163Product: A/V Tuner PreamplifierHardware Technical Bulletin: T163-H2004-033. Mount the front panel ground cable to the nearest front panel screw as shown in figure 8.Figure 8Contact:NAD Electronics International633 Granite CourtPickering, ON Canada L1K 3K1Voice: 905-831-0799 FAX 905-837-