Yamaha MS400 Service Manual page 18

MS400
QQ
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• Finished product inspection
1. Preparation
1) input terminal: LINE INPUT (XLR)
2) OUTPUT: LF
HF
3) LINE LEVEL: MAX(10)
4) MIC LEVEL: MIN(0)
5) MASTER LEVEL: MAX(10)
6) TONE CONTROL HIGH: Center click position (0)
7) TONE CONTROL LOW: MAX(0)
2. Inspection
1) Input a 20Hz to 20kHz, 0.08V(-19.72dBu) sine wave
signal to the input terminal LINE INPUT (XLR) and
check that none of the contact of the voice coil, air
leakage and abnormal noise such as vibration noise
occurs.
Next, input music signals to the input terminal LINE
INPUT (XLR), move each VR knob and check that
the sound volume and tone quality change smoothly
without producing noise.
2) Phase of speaker output
TE
Check that the output at LF is in positive phase with
L 13942296513
respect to the input signal and the output at HF is in
negative phase with respect to the input signal.
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