Yamaha DME24N, Руководство по обслуживанию

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84
DME24N/DME64N
e
Total Harmonic Distortion
r
Noise Level
Measuring Method··· Terminate the CHn input with
150
Ω
. Measure noise levels output from the CHn output.
(n =1~8)
If the noise level is not within the above tolerance, check
EIN (Eqivalent Inpit Noise) that EIN = Noise Level
Measured Value – (Voltage Gain at 1kHz)
≦ -127.
t
Level Difference between CHs
The range of voltage gain difference measured in the
above step
q
will be defined as follows.
2-1-2-4 Voltage Gain Test for HA-GAIN
Press “ENTER” to return “TEST CASE No. Selection
Mode” for a time.
Select the “TEST CASE:#3” (see 2-1-2-1 Diag Mode
Settings), and press “ENTER”.
In the similar procedure to the above, select the “TEST
CASE:#4” and press “ENTER”.
In the similar procedure to the above, select the “TEST
CASE:#5” and press “ENTER”.
Permissible range
-63dBu or below
Permissible range
Within 2dB
Input Frequency Input Level Specified Output Level Permissible range
1kHz -17dBu +4dBu +4
±
2dBu
Input Frequency Input Level Specified Output Level Permissible range
1kHz -37dBu +4.5dBu +4.5
±
2dBu
Input Frequency Input Level Specified Output Level Permissible range
1kHz -46dBu +4.5dBu +4.5
±
2dBu
2-1-2-5 Phantom DC Voltage Test
Measuring Method
· Short-circuit a “+ terminal” and a “-terminal” of CHn,
and connect a 10k
Ω
load between the “-terminal”
and a “GND terminal”.
· Press “ENTER” to return “TEST CASE No. Selection
Mode” for a time.
· Select the “TEST CASE:#6” (see 2-1-2-1 Diag Mode
Settings), and press “ENTER”.
· Measure DC voltage difference between the “-
terminal” and the “GND terminal” of CHn. (n=1~8)
Press “ENTER” to return “TEST CASE No. Selection
Mode” for a time.
Select the “TEST CASE:#7” (see 2-1-2-1 Diag Mode
Settings), and press “ENTER”.
After turning the PHANTOM power “OFF,” check that
the voltage difference between the “-terminal” and the
“GND terminal” decreases immediately.
2-1-2-6 Analog CH 1-8 IN → CH 1-8 OUT
(Test at WORD CLOCK “INT 48kHz”)
Measuring Points··· Analog CH 1-8 OUT
Measuring Method··· Input an analog signal from CHn
input, and measure an output signal from CHn output.
(n=1~8)
a. Characteristic Test at HA-GAIN: MIN (HA-GAIN
setting = “10dBu”)
Enter the Diag Mode, select the “TEST CASE:#7” (see
2-1-2-1 Diag Mode Settings), and press “ENTER”.
(If this setting is performed at the measurement in the
section 2-1-2-5, this setting can be omitted.)
q
Total Harmonic Distortion
w
Noise Level
Measuring Method··· Terminate the CHn input with
150
Ω
. Measure noise levels output from the CHn
output.(n =1~8)
Permissible range
DC 33~36V
Permissible range
-82dB or below
Input Frequency Input Level Output Level Permissible range
(Reference Value)
1kHz -50dBu +14dBu 0.05% or below
1kHz -42dBu +22dBu 0.02% or below
20Hz -50dBu +14dBu 0.05% or below
40kHz -50dBu +14dBu 0.05% or below
Input Frequency Input Level Output Level Permissible range
(Reference Value)
1kHz +20dBu +14dBu 0.02% or below
20Hz +20dBu +14dBu 0.02% or below
20kHz +20dBu +14dBu 0.03% or below