Power Amplifier Check - Yamaha EMX512SC Service Manual

EMX512SC/EMX312SC
Notes:
• Attack time: restoration time (at 90 %) after changing the input level from –42 dBu to –32 dBu. (Fig. 2-16-5)
• Release time: restoration time (at 90 %) after changing the input level from –32 dBu to –42 dBu. (Fig. 2-16-5)
ATTACK TIME
Rectangular wave
Sine wave
Restoration Time
3.

Power Amplifier Check

3-1 Preparation
• Unless otherwise specified, the controls and inputs should be set as follows:
• Input terminal:
• POWER AMP switch:
• Output terminal:
• Load resistance:
• MAIN MASTR control:
• MONITOR MASTER control:
• LEVEL control (channel 5/6):
• MONITOR control (channel 5/6):
• LEVEL control (channels 1-4, 7/8-11/12):
• Other controls (channels 1-4, 7/8-11/12):
• Unless otherwise specified, both channels set for drive.
• Unless otherwise specified, load resistance of SPEAKERS is connected only when inspecting a power amplifier.
• Unless otherwise specified, the input signal should be 1 kHz sine wave.
• The input signal impedance should be 150 Ω.
• Use the load resistance with sufficient capacity.
3-2 Gain
Check the output voltage is within the range specified in the table 3-2-1.
Table 3-2-1
EMX512SC
EMX312SC
Note:
• The difference in the level between each output terminals should be 2 dB or less.
3-3 Output Noise Level
Set the LEVEL control, MONITOR control of channel 5/6, MONITOR MASTER control, and MAIN MASTER control to minimum.
Then check the noise level at the output terminal is less than the value specified in the table 3-3-1.
Table 3-3-1
EMX512SC
EMX312SC
54
RELEASE TIME
Sine wave
90% 100%
LINE R SPEAKERS (A2, B2)
–21 dBu +26.3±2 dBu
–21 dBu +24.0±2 dBu
SPEAKERS (A2, B2)
–65 dBu
–65 dBu
Restoration Time
90% 100%
Fig. 2-16-5
LINE R (channel 5/6)
MAIN (L+R)/MON
SPEAKERS A2 and SPEAKERS B2
4 Ω±1 %
Maximum (10)
Maximum (10)
Maximum (10)
Maximum (10)
Minimum (0)
Minimum