NAD-T163-pre-tb3 维修电路原理图.pdf

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1、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 thesoftwa

2、re 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 fr

3、om 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 se

4、e 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 th

5、e 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

6、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 t

7、his 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

8、 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 wi

9、re 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

10、 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-