Yamaha M7CL-32 Service Manual page 120

M7CL-32/M7CL-48
A. GAIN MAX
(1) Gain
Input Frequency Input Level
1 kHz –60 dBu
(2) f characteristic
Parameters: 1 kHz is used as the reference of the permissible range.
Input Frequency Input Level
20 Hz –60 dBu
20 kHz –60 dBu
(3) Distortion factor
Input Frequency Output Level
1 kHz +22 dBu
(4) Noise level EIN
Parameters: Short TALKBACK IN with 150 Ω.
Permissible Range
–64 dBu or below
If the measured value is out of the above permissible range,
check for:
Measured value – (gain at 1 kHz) –128
B. GAIN MIN
(1) Gain
Input Frequency Input Level
1 kHz –16 dBu
(2) Distortion factor
Input Frequency Output Level
1 kHz +22 dBu
(3) Noise level
Parameters: Short TALKBACK IN with 150 Ω.
Permissible Range
–80 dBu or below
C. Phantom voltage
With No.2 and No.3 pins of XLR shorted and 10 kΩ load
connected between No.2 and No.1 pins, adjust the voltage when
the +48 key is turned on as follows.
Permissible Range
DC33 — 37 V
Also, check that discharging starts immediately when the +48
key is turned off.
3. DIGITAL OUT Characteristic Inspection
3-1. 2TR OUT DIGITAL
Parameters: Use System Two.
Input from CH1 IN.
Set GAIN to +10dB.
A. WORD CLOCK INT48 kHz
Parameters: Adjust WORD CLOCK to INT 48 kHz.
120
Prescribed Output Level Permissible Range
+4 dBu +4±2 dBu
Permissible Range
–1.5 — 0.5 dB
–1.5 — 0.5 dB
Permissible Range
0.02 % or below
< =
Prescribed Output Level Permissible Range
+4 dBu +4±2 dBu
Permissible Range
0.01 % or below
(1) Gain (2TR OUT DIGITAL)
Input Frequency Input Level Prescribed Output Level Permissible Range
1 kHz +10 dBu
(2) f characteristic (2TR OUT DIGITAL)
Parameters: 1 kHz is used as the reference of the permissible range.
Input Frequency Input Level
20 Hz +10 dBu
20 kHz +10 dBu
(3) Distortion factor (2TR OUT DIGITAL)
Input Frequency Output Level
1 kHz –2 dBFS 0.002 % or below
3-2. PLL Operating Range of WORD CLOCK IN
Parameters: Use System Two.
Use OMNI OUT 15 (L) when measuring L channel.
Use OMNI OUT 16 (R) when measuring R channel.
Select WC IN for WORD CLOCK.
Input from CH1 IN.
Set GAIN to +10 dB.
A. 48 kHz+6 % (50.88 kHz)
Parameters: Set the frequency of the oscillator to 48 kHz + 6%.
(1) Distortion factor (WORD CLOCK IN)
Input Frequency Output Level
1 kHz +22 dBu 0.01 % or below
B. 44.1 kHz–10 % (39.69 kHz)
Parameters: Set the frequency of the oscillator to 44.1 kHz –10%.
(1) Distortion factor (WORD CLOCK IN)
Input Frequency Output Level
1 kHz +22 dBu 0.02 % or below
3-3. Jitter Measurement
Parameters: Use System Two.
Select Sec, PK.
BW: Select 700 Hz to 100 kHz.
Use 2TR OUT DIGITAL for the inspection.
A. WORD CLOCK INT
Parameters: Select the values in the following table for WORD
CLOCK.
(1) Jitter
WORD CLOCK Permissible Range
INT44.1 kHz 2 nsec or below
INT48 kHz 2 nsec or below
B. WORD CLOCK EXT
Parameters: Select WC IN for WORD CLOCK.
When testing, set the frequency of the oscillator as
given in the table below.
–20 dBu –20±2 dBFS
Permissible Range
–1.0 — 0.5 dB
–1.0 — 0.5 dB
Permissible Range
Permissible Range
Permissible Range