T763-H2004-01 - Wiki Karat
Contents
1. NAD Technical Bulletin T763 Product A V Receiver Hardware Technical Bulletin T763 H2004 01 Date June 15 2004 Subject Residual Noise Note Implemented in production from Serial number R44T76303751 Previous T B s required Q YES NO DESCRIPTION At high volume setting with no signal on an un terminated analogue input there maybe some audible residual hum noise and whistling sound coming from one or more channels REASON The residual noise is coming from power supply ground and DSP board ground The whistle noise is coming from the DSP board SOLUTION Remove the DSP board and order a replacement DSP board from our spares department Order under the number in the service manual Perform the following ground changes to lower residual hum noise T763 Ground changes 1 Change the cable between J617 on Pre out board and Multi channel RCA from AWG22 to AWGI8 Figure 1 Note If this is not present on the unit add AWG18 cable between Pre out RCA and Multi channel RCA Page 1 of 4 NAD Technical Bulletin T763 Product A V Receiver Hardware Technical Bulletin T763 H2004 01 T763 Ground Changes 2 For J705B on AUDIO PCB cut all the AGND pin That is pin 1 3 9 amp 12 Please refer to figure 2 i i 3 Install a 18AWG ground wire from the DSP board to the Multi channel RCA connector ground See Figure 3 L _ 7 X Figure 2 Figure 3 Page 2 of 4 Mew Technical Bulleti2. n 1763 Product A V Receiver Hardware Technical Bulletin T763 H2004 01 T763 DSP Changes 4 When installing new DSP board please perform the following Float the DSP AGND including the grounding bracket from chassis using an insulated washer See figure 4 and figure 5 FIGURE 4 m a T mpe Wa Fy F EFE E a T FSi ia E E ce er m mA I ii i r f n roi iin La ee a at ak F T E T f oe i amip E i f a aka ui T y z Ms p maian oe Contact NAD Electronics International 633 Granite Court Pickering ON Canada LIK 3K1 Voice 905 831 0799 FAX 905 837 6357 www nadelectronics com Use insulation bushing Page 3 of 4 Mew Technical Bulletin 1763 Product A V Receiver Hardware Technical Bulletin T763 H2004 01 T763 DSP Changes 5 Mount the front panel ground cable to the nearest front panel screw See figure 5 Figure 5 Isolate the PCB ground from chassis Contact NAD Electronics International 633 Granite Court Pickering ON Canada LIK 3K1 Voice 905 831 0799 FAX 905 837 6357 www nadelectronics com Page 4 of 4
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