Symptoms: user said on the phone this DSP-A1 power each channel volume maximum volume output, adjust the volume knob is invalid, as this amp power, push the floor box, but now she would have to listen to music every day dare to boot.msmservice manual download site
Spectator reviews: DSP-A1 and DSP-A2 are the early listed flagship of Yamaha AV amplifier, where A1 on the decoding and better than some, the difference between two models A1 levels after more powerful, decoder Board materials used are more abundant.msmservice manual download site
Maintenance: energized to not pick up the speakers, because output on Max volume very shocked, a bit much. Intuitive oscilloscope for monitoring audio output is also more convenient. Audio signals from the input panel to enter and after switching circuit to decode Board, then output to the mixer to adjust the volumemsmservice manual download site
msmservice manual download site
Volume potentiometer not General of carbon film resistance regulation method, but touch controlled type knob switch, through volume control chip NJU10582 to control each road volume of output size, according to Yamaha amplifier maintenance experience, General chip is not easy bad of, first check perimeter work conditions, 12 v work voltage normal, check circuit diagram displayed 4th feet for inhibit level, add-ins 10UF capacitor, measurement the feet work voltage for 12 v, normal should to 3 v around, observation capacitor introduction feet at has corrosion phenomenon, When you replace the capacitor test machine volume adjustment is normal.msmservice manual download site
msmservice manual download site
IC working conditions tend to generate some strange phenomena are not met, the most typical is the insufficient voltage or voltage is too high. Not long ago, I encountered a pedicle Jacques Music Center, customers bought from Hong Kong for a week just doesn't work, and it is not convenient to take it back under warranty, so let me be repaired. After an inspection found the amplifier section of the machine is good, CD part is good, the problem is the sound volume control has no output signal, which functions by an unknown chip, measuring chip power found that

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