Foot 4 feet into the r48 send CN13 volume potentiometer sent to the front of the connector, C32 C33, CN8 input of left and right channel audio signal by the R38, R39 partial pressure after the merger, the C38 sent to the operation amplifier U5 of the foot of amplification, amplification of signal from the output by removing high frequency components are sent to the U5 3 feet by an internal amplifier amplification, and then from the foot of the output by C31 and CN13 panel bass adjustment BASS1 heavy bass to adjust, and then through the connector to the main circuit board, the power amplifier circuit U8, enlarged after the bass signal from the output, the output of the cn2 connector to promote the main speakers heavy bass loudspeaker sound.

Two, common troubleshooting

Maintenance of the sound box circuit, detection of power supply in the off state and 16V is normal, if not normal fault in city electrical input and a rectifying filter circuit; second, check the amplifier circuit TDA2030A the pin voltage. The integrated circuit with negative power supply, input end, feet and the output voltage of the terminal 4 feet normal voltage were around 0V, if the output end 4 feet of the output voltage to 0V, please shutdown, avoid burn out the speaker. When maintenance is recommended to use a cheap speaker test machine, to avoid causing damage. Maintenance by tens of ohms 5W above resistance instead of the speaker, power amplifier circuit board fixed, confirm the TDA2030A is 4 feet or speaker socket voltage at both ends of the 0V, then connect the speaker test machine.

[tip] if the TDA2030A using single power supply, the power supply is generally used ten 24V power supply, legs of the normal voltage is as follows: the foot is power supply end is 24V. Output end of the foot 12V, 2 feet inverting input 12V, foot positive phase signal input end of 12V.

Fault phenomenon 1: silent, light is not bright.

Analysis and maintenance: this fault more power supply transformer primary open circuit. The failure accounted for more than half of the speakers fault, the reason, one is the poor quality of the power transformer, power reserve is insufficient; the second is no fuse and an overvoltage protection element of the input terminal of the city electricity, when the city electricity voltage rising, transformer burned; the third is the power amplifier circuit short-circuit fault, the current surge will burn out the transformer.

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