Yamaha AD824 Service Manual page 36

AD824
INSPECTION
1. Preparations
1-1 Conditions
· The setting for AD824 is gain 10 dB, word clock INT 48 kHz.
· Word clock in 75 ohms is set to on.
· Signal input of only the CH to be measured.
· Input signal to NCH when measuring NCH.
· 0 dBu=0.775 Vrms
· The output impedance of the oscillator connected is 150 ohms.
· The input impedance of the oscilloscope and the level meter should be more than 100 k ohms.
· Noise measurement is corrected at 12.7 kHz, -6dB/OCT LPF.
(This is a measurement of the average value and not the actual effect value.)
· Distortion measurement is corrected at 80 kHz, -6 dB/OCT LPF.
· Use DA824 and MY8-AE card and output signal.
· The load for DA824 output 1 to 8 is 600 ohms.
· DA824 output 1 to 8 is measured at the cannon connector.
· DA824 internal gain SW is +18 dB.
1-2 Initialization
While pressing the [SEL4] key and [+48V] key, turn on the power switch. The system will start up and initialize.
2. Inspections
2-1 INPUT1 to 8CH
(1) Gain
Input frequency
1 kHz
(2) f characteristics
Conditions: Permissible range uses 1 kHz as a reference.
Input frequency
20 Hz
20 kHz
(3) Distortion ratio
Input frequency
20 Hz
20 kHz
1 kHz
(4) Residual noise
Conditions: Input 1 to 8 channels shorted using 150 ohms.
GAIN
+10 dB
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Input level
+10 dB
+4 dB
-2 dB
-8 dB
-14 dB
-20 dB
-26 dB
-32 dB
-38 dB
-44 dB
-50 dB
-56 dB
-62 dB
Input level
+10 dBu
-62 dBu
+10 dBu
-62 dBu
Input level
+10 dBu
-62 dBu
+10 dBu
-62 dBu
+24 dBu
-48 dBu
Permissible range
Less than -90 dBu
GAIN Specified output level (DA824)
+10 dB
+4 dB
-2 dB
-8 dB
-14 dB
-20 dB
-26 dB +4 dBu
-32 dB
-38 dB
-44 dB
-50 dB
-56 dB
-62 dB
GAIN Permissible range
+10 dB -1.5 to +1 dB
-62 dB -3 to +1 dB
+10 dB -1.5 to +1 dB
-62 dB -3 to +1 dB
GAIN Specified output level (DA824)
+10 dB +4 dBu
-62 dB +4 dBu
+10 dB +4 dBu
-62dB +4 dBu
+10 dB +18 dBu
-62 dB +18 dBu
Permissible range
+4 +/-1 dB
Permissible range
Less than 0.05 %
Less than 0.1 %
Less than 0.05 %
Less than 0.1 %
Less than 0.01 %
Less than 0.05 %