Bose Acoustimass 3 Series 서비스 매뉴얼 - 페이지 12

{카테고리_이름} Bose Acoustimass 3 Series에 대한 서비스 매뉴얼을 온라인으로 검색하거나 PDF를 다운로드하세요. Bose Acoustimass 3 Series 42 페이지. Powered speaker system
Bose Acoustimass 3 Series에 대해서도 마찬가지입니다: 소유자 매뉴얼 (17 페이지), 소유자 매뉴얼 (10 페이지), 매뉴얼 (43 페이지)

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12. DC Offset Protection

If any one of the three amplifier channels should fail, it is likely that a large DC voltage will occur

at the output of that channel. If this occurs, the DC offset detect circuit will cause the AM-3P

amplifier power supply to shut down. It will remain shut-down until the unit is unplugged from

the power source. This provides a safe indication to the customer that the unit requires service.

Detailed operation is as follows: The amplifier outputs are summed by resistors R149,249,318,

and 418, and (low pass) filtered by capacitor C29. For a sustained DC offset, C29 will charge

either negative or positive. A positive offset will trigger Q7 and a negative offset will trigger Q8.

This in turn causes Q6 to conduct and latches Q5 permanently on. Q5 then shorts the emitter

of Q4 to ground (off). Q4 is the transistor that controls turn-on of 2P1T relay K1 (on the Amp

PCB) that is used to connect +/- 20V supply rails to the power amplifiers. Thus, the amplifiers

are de-energized.