Kenwood SW-900 subwoofers specifications: rated power 100W (8 ohms), 90dB sensitivity, floor-standing, dual 6.5-inch woofer. The subwoofer sound good, infrared remote control, large sales. Currently I have yet to find Kenwood model SW-900 subwoofer circuit diagram data measured in repair the machine circuit diagram (Note: effective symbols the symbols for circuit board circuit diagram components), sharing with the general maintenance of the peer.aDLservice manual download site
1.SW-900 power supply circuit diagramaDLservice manual download site
Power supply circuit diagram is shown in Figure 1. This circuit includes a figure of 1-1 for transformer rectifier circuit, the output voltage ± 42V; 1-2 +5V regulated power supply circuits, power to the CPU; figure 1-3 for the +12V power supply circuit, Figure 1-4 is -12V regulated power supply circuits, signal channel circuit the power supply. Complex is ± 12V voltage regulator circuit, this circuit can remote-control shut off 12V power supply. Work principle analysis is as follows: remote shutdown, CPU IC D75004CU Q38 25 pin 0V output voltage saturation of conduction, causing the Q33 saturated hydraulic conductivity, and Q32 and Q31 globe, +12V down. +12V after the electricity supply was cut, Q34 b voltage negative voltages, Q34, saturated hydraulic conductivity, and Q35 and Q36 globe, -12V down. 25 pin of the CPU when the voltage is +7.5V, 12V voltage regulator circuits started power subwoofer work.aDLservice manual download site
aDLservice manual download site
2.CPU and volume control circuitaDLservice manual download site
Circuit diagram is shown in Figure 2, the key pin functions are shown in table 1.aDLservice manual download site
aDLservice manual download site
aDLservice manual download site
Volume control potentiometer model of micro-motor IC TA8409S, pin functions are shown in table 2.aDLservice manual download site
aDLservice manual download site
3. amplifier and subwoofer controlaDLservice manual download site
Circuit diagram is shown in Figure 3. Signal flow is as follows: RCA socket audio input signal to IC1 (JRC4565) II feet, amplified output from ① foot; then enter the IC4 (JRC4565) and aim at foot, amplified output from ① foot; then entered into a four-way switch circuit is an audio filter network D4066BC II foot switch, switch directly into the volume potentiometer. External input audio signals input to the IC1 ⑥ feet, amplified from ⑦ foot M5134P h foot bass output to digital processing circuit. Along the signals after the Digital Bass output from 18 feet, and then enter the IC4 II feet, IC4, 1th amplifier. Two signals after the IC4 1th amplifier mixing amplifier, and output to a volume potentiometer.

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