Most of the desktop computer configuration of the active speaker, and this type of speakers are not configured circuit diagram, which brings trouble to repair. The author repeatedly maintains the multimedia active speaker, found most amplifier circuit TDA2030A. The author will recently repair the EARSON multimedia active speaker circuit analysis, for reference.a3Nservice manual download site
EARSON multimedia active speaker models for ER2801 (ER2809 of the circuit identical with it), the internal principal circuit board of positive and negative were as in Figure 1 and Figure 2 shows, on the main circuit board is composed of three power amplifier circuit TDA2030A 2 + 1 channel amplifier circuit, namely the left channel, right channel, the bass sound channel three amplifying circuit, drawing the circuit as shown in Figure 3.a3Nservice manual download site
One, working principle analysisa3Nservice manual download site
The sound box amplifier circuit uses three TDA2030A, are designed for the OCL circuit, uses the positive, the negative power supply. TDA2030A containing short circuit protection, thermal protection, ground occasionally open circuit, power supply polarity reverse connection Vsmax=12V and load discharge kickback voltage circuit can work under minimum scholar 6V and the scholar 22V voltage. When the input voltage is 19V, the load impedance is 8 ohms, effective power output of 16W, the total harmonic distortion is less than 0.1% THD. TDA2030A Pinout: feet, the positive phase signal input; (2 feet, inverting input; 3 feet, negative power supply terminal; 4 feet, output, foot, is the power supply end of the power supply.a3Nservice manual download site
AC220V power, power step-down transformer for voltage double AC11.2V, and rectified by the diode d5-d8, C20, C21 filter, formed off state and 16V voltage, three pieces of TDA2030A power supply; pre small signal amplifier LM4558 (U5) power supply is off state and 16V R45, R46 step-down get.a3Nservice manual download site
Left and right channel audio signal first sent to the front control panel, through two double potentiometer (Vol TRE) volume, tone control, again through the connector CN8 sent to the board of the left and right channel amplifier circuit, which left channel signal the R33, C26, C25 sent to power amplifier circuit U6 (TDA2030A) of foot; the right channel signal by R36 C27, C24 sent to power amplifier circuit U7 (TDA2030A) of foot; U6, U7 amplification of the audio signal output from the 4 feet, through the output connector is received, promote left and right channel speaker sound.

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