Inspections; Measuring Instruments; Analog In/Out Characteristic Inspection; Updating The Program - Yamaha M7CL-32 Service Manual

M7CL-32/M7CL-48

INSPECTIONS

1. Preparation

1-1. Measuring Instruments

Use measuring instruments which can measure the inspection
items accurately with confidence.
Input impedance of the measuring device should be 100 kΩ or more.
· System Two
· Tester
· Filter (12.7 kHz, –6 dB/OCT)
· Level meter
1-2. Parameters
◊Unless otherwise specified, the parameter settings are as
follows.
· Set the WORD CLOCK to INT 48 kHz.
· Set the "+48V MASTER" to ON.
· Turn on only the channel being measured.
PAN :
GAIN :
FADER :
PHONES LEVEL :
TALKBACK GAIN :
· 0 dBu = 0.775 Vrms
· 0 dBFS = 0 dB, full scale
· Set the oscillator output impedance to 150 Ω.
· Correct with LPF at 12.7 kHz, –6 dB/OCT during noise
measuring.
(For measurement, use the average values and not effective
values.)
· Correct with LPF at 80 kHz, –18 dB/OCT during distortion
measuring.
◊For analog output inspection, add or change parameter settings
as follows.
· For maximum output measurement, unless otherwise
specified, output 0 dB from the internal oscillator.
· Set the analog output loads as follows:
OMNI OUT:
PHONES(x 2):

1-3. Updating the Program

If the main program is not the latest version, it is necessary to
update it to the latest version.
∗ For the latest version, download the latest program from the
YSISS home page and save it in the USB memory device.
(1) How to check the version of the main program
Press the MENU in the LCD screen and the current version will
be shown in the "SETUP" page screen.
(2) How to write programs
For the program writing procedure, refer to the "LOADING THE
PROGRAM" section in the "SERVICE CHECK PROGRAM".
(See page 126)
118
CENTER
MIN
NOMINAL (0 dB)
MAX
MAX
600 Ω
8 Ω
1-4. Initialization
Refer to "Initializing the internal memory" for Initializing the
internal memory. (See page 189)

1-5. Fader Calibration

Refer to "Calibration function: Calibrating faders" for calibrating
faders. (See page 192)
1-6. CPUM circuit board SRAM Backup Inspection
Check that "== INITIALIZE MENU ==" does not appear on
the LCD screen when the power is turned on.

2. ANALOG IN/OUT Characteristic Inspection

2-1. OMNI OUT 1—16
Parameters: Input from INPUT (XLR) of CH1.
Assign CH1 to OMNI OUT 1—16.
(1) Gain (OMNI OUT 1—16)
Input Frequency Input Level Prescribed Output Level Permissible Range
1 kHz +10 dBu
(2) f characteristics (OMNI OUT 1—16)
Parameters: 1 kHz is used as the reference of the permissible range.
Input Frequency Input Level
20 Hz +10 dBu –1.5 — +0.5 dB
20 kHz +10 dBu –1.5 — +0.5 dB
(3) Distortion factor (OMNI OUT 1—16)
Input Frequency Output Level
1 kHz +22 dBu 0.01 % or below
(4) Residual noise(OMNI OUT 1—16)
Parameters: Turn off STEREO.
Permissible Range
–86 dBu or below
(5) OMNI OUT 1—16 level difference
Adjust the range of difference in the gain measured in item (1)
above as follows.
Permissible Range
Within 1 dB
(6) Crosstalk between adjacent channels (OMNI OUT 1—16)
Parameters: Turn on OMNI OUT of only one odd number channel
for output with OMNI OUT of other channels turned
off and measure the noise level of even number
channels next to the odd number channel on both side.
Input Frequency Output Level
(Odd Channel) (Even Channel)
1 kHz +23 dBu –57 dBu or below
Perform the same check on the even number channels.
+4 dBu +4±2 dBu
Permissible Range
Permissible Range
Permissible Range