The unit's power supply with dual toroidal transformer, the transformer secondary output AC 18V, bridge rectifier obtain a 25V power supply voltage, supply of C5198/A1941 for the power output tubes power amplifier Board.2D8service manual download site
2D8service manual download site
The signal flow: jacks of the input signal after a total of five groups, namely, VCD, DVD, AUX, LD, TAPE, after select touch-panel signals to control audio source select integrated CD4 () elected 52, volume potentiometer control evacuations to tone plate.2D8service manual download site
2D8service manual download site
Tone plate TL084-centric composition, microphone signal is also sent to pitch, which means volume potentiometer, that only after the control input signals or closed will not affect the microphone output signal. After treble and bass control, L/R signal sent through a shielded cable to the power amplifier the amplifier Board and eventually the speaker protection relay for speakers.2D8service manual download site
2D8service manual download site
Understand signal processes need to know is: 50Hz by interfering sound is power amplifier Board, tone, or a microphone? First of all unplug the amplifier input plug, sound 50Hz interference undermined; restoration plug, plug unplug the CD4052 output to tones, sound 50Hz interference; restoration plug, unplug the microphone Board to tone signal plug, sound 50Hz interference to determine points of failure in the receiver plate.2D8service manual download site
2D8service manual download site
Handset 1, handset 2, microphone treble potentiometer enclosure grounding, interfering sound much lower. Observe the microphone close to the toroidal power transformer, suspect that transformers are sources of interference. Move 15cm to the rear of the amplifier power transformer, power up sound completely excluded, try 50Hz interference.2D8service manual download site
2D8service manual download site
Sound 50Hz interference to eliminate, but owners are still scratching their heads, why when I first bought this fault is not? This is only recently getting serious, and this problem really is no easy answer.2D8service manual download site
2D8service manual download site
When testing speakers, plays familiar music, break, unable to feel the bass, too soft cotton, makes people feel like the bass potentiometer open end, treble potentiometer when close to the end. Open the loudspeaker protection nets, press 15-inch bass vibration found speakers spring is soft, hardness less than the conventional 6-inch bass spring boards, it should be a 15-inch woofer for 50Hz interference "highly sensitive"----15-inch bass into a few of the reasons why the sub woofer.

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