16
XH150
8. Channel Separation Test
8-1 Apply a - 5 dBu, 20kHz sine wave into the channel A input.
8-2 Short the input to channel B with a 600 ohm load.
8-3 Set the output of channel A at a reference of 0 dB.
8-4 If the channel B attenuator is set to the same as channel A, channel B output should be less than -65 dB. (RL = 64 ohm)
9. Noise Test
9-1 Set the input attenuator at maximum.
9-2 Short the input to the GROUND with a 600 ohm load.
9-3 The output noise level should be less than - 61 dBm.
9-4 Set the input attenuator at "oo," the noise level should be less than - 65 dBu.
* Be careful that this is not affected by noise induced during the inspection.
10. Stability Test
When a rectangular wave of 10 kHz, - 10 dBu is applied to the input and a capacitor of 10 pF - 0.47
µ
F is connected with a 32 ohm load
resistor in parallel, the overshoot and the ringing should be as follows.
Overshoot: Vp/Vo <= 1.8
Ringing: less than 5 waves
Next, when the 32 ohm load resistor is removed and the load is only the capacitor 10 pF - 0.47
µ
F, the overshoot and the ringing should
be as follows.
Overshoot: Vp/Vo <= 2.5
Ringing: fades away in less than 7 waves and no oscillation
11. Protection Circuitry Test
Check that the relay does not work when you apply a sine wave of + 3.0 dBu at 10 Hz to the input and adjust the input level to obtain a
clipped output wave form.
Next, check that when you apply a sine wave of 1 Hz, 6.3 dBu to the input, the signal is cut off within 2 seconds, and the PROTECTION
indicator lights up.
Finally, check that when no signal is applied, the amplifier resumes to normal operation within 10 seconds.
12. PC Limiter Circuitry Test
Check with an oscilloscope that the OUTPUT is as follows when a sine wave of -14 dBu at 1 kHz is applied to the INPUT and the output
is shorted with an 8 ohm load (+/- 5 %). At this time, check that the CLIP indicator lights up.
Output level: Vp-p <= 30 V
*This test should be finished within 30 minutes.
13. OUTPUT VOLTAGE Switch Check
OUTPUT VOLTAGE switch 70V:
Check that the OUTPUT is Vp-p <= 230 V, when a sine wave of 1 kHz at 6.0 dBu is applied to the INPUT.
C. Others
0 dBu = 0.775 V
When measuring the noise level, use a DIN audio filter.
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