Service manual

40
EMX68S / EMX88S
2.9 EIN Check
Note: This mesurement should be performed by using DIN AUDIO FILTER.
On condition of 2.1, set the LEVEL knob for mesuring channel to maximum, set the PAN or BAL/PAN knob to the left limit and
set the LEVEL knob 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 CH3, 4 (EMX68S) / CH5, 6 (EMX88S).
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, 2, 5, 6 (EMX68S) / CH1-4, 7, 8 (EMX88S), and less than
-122dB as for CH3, 4 (EMX68S) / CH5, 6(EMX88S).
2.10 Remaining Noise Check
On condition of 2.1, set the LEVEL knobs of all input channels to minimum.
Next, set the MASTER knobs of MAIN and MONITOR to maximum or minimum, and mesure the noise level of MAIN OUT,
MONITOR OUT, and EFFECT OUT. (without MASTER level control)
Then, confirm that the noise levels are less than the values shown in the table 2.10-1.
Table 2.10-1 [unit: dB]
MASTER VR MAIN OUTPUT(L,R) MONITOR OUTPUT EFFECT OUT
MAX -73 -69 -84
MIN -94 -94 -
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±3V when the PHANTOM switch is ON.
2.12 DIGITAL EFFECT Check
• Confirm that the ON LED lights up when the DIGITAL EFFECT ON switch is ON, and that the LED goes out when the switch
is OFF.
• Set the PROGRAM select switch to 16, PARAMETER VR to minimum, and EFFECT RTN control of MONITOR to maximum.
At CH1, set the MONITOR level control to minimum, EFFECT level control to maximum, LEVEL control VR to maximum,
and input -60dBs signal into Low-Z terminal.
Then confirm that the output level is more than 0dBs when the DIGITAL EFFECT ON switch is ON.
2.13 STAND-BY Check
On condition of 2.1, apply the signal into CH1 Low-Z terminal so that each output level of MAIN (L, R) OUT, MONITOR OUT,
EFFECT OUT becomes +14dB.
Confirm that the output level becomes less than -46dB when the STAND-BY switch is turned on.
Besides, confirm that the LED blinks.
2.14 Stability Check
Note: This mesurement should be performed with a load resistance connected to power amplifier output.
• 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 volume knobs and EQ faders to maximum, and confirm that the system works normally. (Especially, does not oscillate
when the EQ HIGH is set to maximum)