7-3-7. Audio Circuit
Fig. 7-3-12 shows the audio circuit block diagram.
Signal path from the QV001 to the LINE OUT terminal is: QV001 ® transistor buffer ® LINE OUT terminal.
Signal path from the QV001 to the speaker is as follows. The audio signal developed from the QV001 becomes one signal with its L and R signal components mixed. The mixed audio signal enters the electrical volume IC QA01 (M5222FP) and the output level is controlled within a range of about 0 dB to –80 dB by an external DC voltage (DAC). The audio signal thus controlled by the IC QA01 is fed to the speaker amplifier IC QA02 (TDA7056A) and amplified by about 36 dB to drive the speaker.
VIDEO
L |
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R | QV001 |
RGB INPUT SELECTOR
L 
CXA1855Q
R
LINEOUT
R
BUFFER 
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| BUFFER |
| QA01 | M5222FP |
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| VOLUME |
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| DAC | VOL / MUTE |
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| MUTE |
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| CXA1315M |
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| QA02 | TDA7056A |
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| SOUND OUT |
| SPEAKER | |
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| 1.5W |
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