Yamaha T3n, Service Manual

Page: 39 / 107

T5n/T4n/T3n
39
3-2-11. Channel separation
Input the sine wave given in the below table to the input terminal of one channel and measure the output voltage as reference
voltage (0 dB).
Then, measure the output voltage at the other channel input grounded via 600 ohms resistance and check that it is -65 dB or
less as compared with the reference voltage.
3-2-12. Output noise level
1) With the input attenuator set at maximum, the input terminal grounded via a 600
Ω
resistance, measure the noise level
occurring at the output terminal and check the measured value is -65 dBu or less.
2) Measure the noise level with the input attenuator set at minimum and check the measured value is -65 dBu or less.
Note:
• Noise should be measured with a DIN AUDIO filter.
3-2-13. Stability
Input 1 kHz, -4.0 dBu square wave, connect 0.1 uF capacity only to the output terminal and check the following conditions are
satisfied.
Overshoot : Vp/Vo 2.5
Ringing : The ringing should be settled down within 7 waves and the oscillation or the like should not be occurred.
3-2-14. Protection circuit
This inspection should be performed with no lord resistance connected to the output terminals.
1) Input 1 Hz, +16.0 dBu sine wave and check the protection circuit does not function.
2) Disconnect the IN connector assembly from CN609 with the input signal turned off, and check the PROTECTION LED
lights in red color within 2 seconds.
After that, turn off the power switch, connect the IN connector assembly to CN609.
Then turn on the power switch and check the PROTECTION LED lights in red color and the POWER LED lights in green
color, and after that about 9 seconds, the muting function is cancelled.
3) Disconnect the IN connector assembly from CN610 with the input signal turned off, and check the PROTECTION LED
lights in red color within 2 seconds.
After that, turn off the power switch, connect the IN connector assembly to CN610.
Then turn on the power switch and check the PROTECTION LED lights in red color and the POWER LED lights in green
color, and after that about 9 seconds, the muting function is cancelled.
Note 1:
• Be sure to perform this inspection with no lord, otherwise the product will be damaged.
Note 2:
• Take care when you disconnect the IN connector assembly from CN609 and CN610.
Because the high DC voltage will be outputted at the output terminal momentary.
T5n
T4n
T3n 7.2 dBu
6.4 dBu
4.9 dBu
Vp
Vo
VR168300 Polyester Multilayer Capasitor
PART NO. DESCRIPTION
0.1 uF 50 V J
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