NAD-T743-avr-tb4 维修电路原理图.pdf

《NAD-T743-avr-tb4 维修电路原理图.pdf》由会员分享，可在线阅读，更多相关《NAD-T743-avr-tb4 维修电路原理图.pdf（2页珍藏版）》请在收音机爱好者资料库上搜索。

1、Page 1 of 2 Technical Bulletin T743 Product: A/V Receiver Hardware Technical Bulletin: T743-H2005-05R Date: March 7/05 Subject: Static protection for muting transistors Note: Implemented in production from serial number:R49T74310201 Previous T.B.s required: Revised from T743-H2005-05 K K K K YES K K

2、 K K NO DESCRIPTION: You may have 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.

3、SOLUTION: Replace the transistor 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

4、each muting transistor is preferred . 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

5、 All other channels RadioFans.CN 收音机爱 好者资料库Page 2 of 2 Technical Bulletin T743 Product: A/V Receiver Hardware Technical Bulletin: T743-H2005-05R 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 and collector pins of muting transistor on the pre amp pc board RadioFans.CN 收音机爱 好者资料库