NAD-T743-avr-tbh200505 电路图 维修手册.pdf

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1、Page 1 of 2 Technical Bulletin T743 Product: A/V Receiver Hardware Technical Bulletin: T743-H2005-05 Date: February 28/05 Subject: Static protection for muting transistors Note: Implemented in production from serial number:R49T74310201 Previous T.B.s required: ? ? YES ? ? NO DESCRIPTION: You may hav

2、e the complaint that the subwoofer or other channels are popping when switching inputs or when turning on and off. REASON: The channel that is popping may have a muting transistor damaged due to an external source or subwoofer causing static damage to the transistor. SOLUTION: Replace the transistor

3、 and install a 4700 pF capacitor between the base and collector on the pre amp pc board , as shown in the following two schematics. The use of a surface mount capacitor is recommended. Placing the capacitor on the bottom of the board between the base and collector of each muting transistor is prefer

4、red . See figure 2 on page 2. Note: It is recommended to install this capacitor to each channels muting transistor.The following are the designations of the muting transistors, Q608,Q609,Q610,Q611,Q615,Q617. Figure 1 muting circuit Subwoofer/Multi. CH.S muting circuit All other channels RadioFans.CN

5、 收音机爱 好者资料库 Page 2 of 2 Technical Bulletin T743 Product: A/V Receiver Hardware Technical Bulletin: T743-H2005-05 Figure 2 Contact: NAD Electronics International 633 Granite Court Pickering, ON Canada L1K 3K1 Voice: 905-831-0799 FAX 905-837-6357 4700pF surface mount capacitor between base emitter pins of muting transistor on the pre amp pc board RadioFans.CN 收音机爱 好者资料库