Yamaha MW12CX Service Manual page 48

MW12CX/MW12C
2-7 Frequency Characteristic
In the signal route 1 to 0 specified in the table 2-6-1 to 2-6-6, check the 20 Hz and 20 kHz frequency response of each output
is within the range of +1/-2.5 dB compared with the 1 kHz (0 dB).
* When the GAIN control is set to maximum, only 20 Hz frequency response is within the range of +1/-4.5 dB compared with
the 1 kHz (0 dB).
* In the signal route 1, check every OUT when the signal is input to CH1, and check only the ST L OUT when the signal is
input to CH2 and other channels.
* In the signal route 4, check only the ST L OUT and the ST R OUT.
2-8 HPF
With controls set as specified in the table 2-6-1 and 2-6-2, set the GAIN control minimum and input 80 Hz, -36 dBu signal to
the input terminal. Set the 80 switch on and then check the output level obtained at ST L OUT is within the range of -3 ± 2 dB
compared with the output level obtained when 80 switch is off.
2-9 Channel Equalizer Characteristics
With controls set as specified in the section 2-2, move each equalizer gain control (HIGH, MID, LOW) respectively and check
the output level obtained at REC OUT2 L and REC OUT2 R for each frequency is within the range specified in the table 2-9
compared with the output level obtained when each equalizer gain control is at center click position.
If the output level is out of range, change the input frequency within the range of ± 20 % and check that the output level is within
the range shown in table 2-9.
Table 2-9
EQ control
HIGH
MID
LOW
2-10 Crosstalk
Set ON switch and ST switch of each input channel to ON, and turn the PAN control (PAN/BAL or BAL control in case of ST CH
INPUT) counterclockwise fully, check the leakage signal level obtained at ST R OUT is -50 dBu or less when the output level
obtained at ST L OUT is +20 dBu.
Also turn the PAN (PAN/BAL, BAL) control clockwise fully, check the leakage signal level obtained at ST L OUT is -50 dBu or
less when the output level obtained at ST R OUT is +20 dBu.
2-11 PEAK indicator light-up level
With controls set as specified in the section 2-2, input signal to the CH INPUT MIC and ST INPUT MIC. Then check the input
level is within the range specified in table 2-11 when the PEAK indicator lights up.
Table 2-11
INPUT
MIC
2-12 Lighting Check of LEVEL meters
Check the "0" indicator of meter lights up when the output level at ST OUT (L, R) is +4 ± 2 dBu.
Move the ST master fader and check the indicators light up in order from "-30" to "PEAK".
48
EQ gain control Input frequency
Max.
10 kHz
Min.
Max.
2.5 kHz
Min.
Max.
100 Hz
Min.
PEAK indicator
-43 ± 2 dBu
Variation width
+12 ± 2 dB
-12 ± 2 dB
+15 ± 2 dB
-15 ± 2 dB
+12 ± 2 dB
-12 ± 2 dB