NAD-T763-avr-tbh200401 电路图 维修手册.pdf

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1、Page 1 of 4 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: ? ? YES ? ? NO DESCRIPTION: At high volume setting with no signal o

2、n 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

3、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 AWG18. Figure 1 Note: If

4、this is not present on the unit, add AWG18 cable between Pre-out RCA and Multi- channel RCA. RadioFans.CN 收音机爱 好者资料库 Page 2 of 4 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

5、, 3, 9 & 12. Please refer to figure 2. Figure 2 3. Install a 18AWG ground wire from the DSP board to the Multi channel RCA connector ground. See Figure 3. Figure 3 RadioFans.CN 收音机爱 好者资料库 Page 3 of 4 Technical Bulletin T763 Product: A/V Receiver Hardware Technical Bulletin: T763-H2004-01 T763 DSP Ch

6、anges 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 Contact: NAD Electronics International 633 Granite Court Pickering, ON Canada L1K 3K1 Voice: 905-831-0

7、799 FAX 905-837-6357 RadioFans.CN 收音机爱 好者资料库 Page 4 of 4 Technical Bulletin T763 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 Contact: NAD Electronics International 633 Granite Court Pickering, ON Canada L1K 3K1 Voice: 905-831-0799 FAX 905-837-6357