Yamaha XP7000, Руководство по обслуживанию

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XP7000/XP5000
40
5. Inspection
5.1 Gain
Input a 1 kHz, -10.0 dBu signal and check that +28.0
±
1.0 dBu output voltage is obtained.
5.2 Frequency characteristics
Input 20 Hz, 1 kHz, 20 kHz, -10 dBu signals and check that the output voltage obtained is within -0.5
±
0.5 dBu at 20 Hz and
20 kHz as compared with the output voltage at 1 kHz.
5.3 Distortion
Input 20 Hz, 20 kHz signals to the input terminal and check that the distortion is 0.1% or less when the output voltage as
specified in the table below is obtained.
This inspection should be completed within 30 seconds.
XP5000
126.50 V
XP7000 (U/T/A)
149.68 V
XP7000 (H/B/K/O)
144.24 V
5.4 Output noise level
Shunt 2 pin (hot) and 3 pin (cold) of input terminals with 600 ohms.
Measure the noise level at the output terminal and check that it is -60 dBu or less.
Next, set the attenuator to MIN and check that the noise level is -65 dBu or less.
Use a DIN AUDIO filter for this measurement.
MEASURING
INSTRUMENT
A+
8 ohms R
8 ohms
XP7000
or
XP5000
INPUT+
INPUT-
R
B+
4. Preparation for BRIDGE mode
Attenuator : “0” (MAX) Only channel A is valid.
Input terminal : XLR connector 2PIN-HOT/3PIN-COLD/1PIN-GND
MODE switch : BRIDGE
GAIN switch : 32 dB
HPF switch : OFF (both channels)
Load resistance : 8 + 8 ohms +/- 1%
Make connections as shown below and measure the output voltage at each point.