Yamaha EMX312SC, Руководство по обслуживанию, Страница: 52 / 140

EMX512SC/EMX312SC
52
2-7 FCL indicator light-up level
With controls set as specified in the section 2-1, check the FCL indicator lights up when the 1 kHz, –73 dBu signal is input to the input
terminal (INPUT B, MIC) of channels 1-11/12. Also check the FCL indicator turns off when the –85 dBu signal is input.
2-8 Lighting Check of LEVEL meters
Check the “0” indicator of meter lights up when the output level at MAIN OUT (L, R) is +4±2 dBu. Move the MAIN MASTER
control and check the indicators light up in order from “–10” to “+6”.
2-9 Distortion Factor
In the signal route
1
to
5
specified in the table 2-3-1 and 2-3-2, set each control of input channels and the MASTER controls to the
nominal position. Then check the distortion is less than 0.5 % when the output signal level is +14 dBu.
Note:
• Distortion should be measured with a 30-kHz low pass filter.
2-10 Maximum Output
In the state specified in the section 2-9, check the distortion factor is less than 1 % when the output level is +20 dBu at MAIN OUT (L,
R) and MONITOR OUT. Also check the distortion factor is less than 1 % when the output level is +16 dBu at EFFECT OUT.
2-11 Equivalent Input Noise
With controls set as specified in the section 2-1, connect pin 2 (hot) and pin 3 (cold) of the INPUT B or MIC terminal with 150
Ω
and
check the noise level obtained at MAIN OUT L is –49 dBu or less.
If the noise level exceeds –49 dBu, calculate the input converted noise level and check it is –114 dBu or less.
Notes:
• Set the LEVEL controls of input channels except measured one to minimum.
• Noise should be measured with a DIN AUDIO filter.
• The input converted noise level is obtained by subtracting the channel gain from the noise level.
2-12 Residual Noise
With controls set as specified in the section 2-1, set the LEVEL controls of all input channels to minimum. Then check the noise level
is less than the values in the table 2-12-1 when the MASTER control is set to maximum or minimum.
Note:
• Noise should be measured with a DIN AUDIO filter.
2-13 PHANTOM
Connect a 2.7 k
Ω
load resistance between pin 1 and pin 2 of the INPUT B or MIC terminal and short-circuit pin 2 and pin 3. Then turn
on the PHANTOM switch and check the PHANTOM indicator lights up and the voltage between pin 1 and pin 2 is 10±1.5 V.
2-14 DIGITAL EFFECT
Turn on the DIGITAL EFFECT ON switch and input the –51 dBu signal to INPUT B terminal of channel 1. Then check the output
obtained is –10 dBu or more with the condition in the table 2-14-1.
Next, input no signal and set the LEVEL control and EFFECT control of channel 1 to minimum. Then check the noise level at
MONITOR OUT is –50 dBu or less. Also feed music source and check effect of the DIGITAL EFFECT at MAIN OUT (L, R) and
MONITOR OUT by listening.
Table 2-12-1
MASTER control MAIN OUT (L, R) MONITOR OUT EFFECT OUT
Max. –75 dBu –67 dBu –80 dBu
Min. –90 dBu –90 dBu
Table 2-14-1
Output LINE/MIC
switch Channel 1
LEVEL control Channel 1
EFFECT control PROGRAM
selector PARAMETER
control
MONITOR OUT MIC Max. Max. 1 Min.