Yamaha EMX62M Service Manual page 31

2.7 Distortion Rate Check
On condition of 2.1, set the INPUT and MASTER volume for each terminal to nominal position.
Then, confirm that the distortion rate is within 0.3% when the output level is +14dBs. (except REC OUT and PHONES OUT)
2.8 Maximum Output Level Check
At MAIN OUT, MONITOR OUT, EFFECT OUT terminals on condition of 2.7, confirm that the output level of +20dBs can be
gained with the distortion rate less than 1%.
2.9 EIN Check
Note: This mesurement should be performed by using DIN AUDIO FILTER.
On condition of 2.1, set the LEVEL control for mesuring channel to maximum and set the LEVEL control for other channels to
minimum.
Connect the 150Ω load between the Low-Z and the MIC of input channel, and confirm that the noise level of MAIN OUT is less
than -58dB.
However, less than -56dB as for CH6.
If noise level is more than the rated value, find the noise level converted from the input level for each channel.
Then confirm that the noise level is less than -124dB as for CH1-5, and less than -122dB as for CH6.
2.10 Remaining Noise Check
On condition of 2.1, set the LEVEL control of all input channels to minimum.
Set the MASTER control of MAIN and MONITOR to maximum or minimum, and mesure the noise level of MAIN OUT,
MONITOR OUT, and EFFECT OUT.
Then, confirm that the noise levels are less than the values shown in the table 2.10-1.
Table 2.10-1
MASTER VR
MAX
MIN
2.11 PHANTOM Check
Connect the 2.7kΩ load between the pin1 and pin2 of Low-Z or MIC, and short-circuit the pin2 and pin3 of them.
Then, confirm that the load voltage is 10±1.5V when the PHANTOM switch is ON.
2.12 DIGITAL EFFECT Check
• Confirm that the ON LED lights up when DIGITAL EFFECT switch is ON, and that the LED goes out when the switch is OFF.
• Apply the music source (vocal etc), and confirm the effect aurally.
• Turn on the DIGITAL EFFECT ON switch, and confirm that sound effect can be switched on or off by using a foot switch.
2.13 Stability Check
Note: This mesurement should be performed with a load resistance connected to power amplifier output. (See 3.1)
• At each input terminal, connect 10pF~0.1µF capacitor in parallel to the load resistance, and confirm that the system works
normally without oscillation etc.
• Set all VR and EQ faders to maximum, and confirm that the system works normally. (Especially, does not oscillate when the EQ
HIGH is set to maximum)
MAIN OUTPUT(L,R) MONITOR OUTPUT
-71
-88
EFFECT OUT
-71 -73
-88 -
EMX62M
[unit: dBs]
31