Inspections; Inspections In Stereo Mode And Parallel Mode; Fan, Power/Protection Led; Power On Muting Time - Yamaha PC4800N Service Manual

PC9500N/PC4800N

INSPECTIONS

1. Inspections in STEREO mode and PARALLEL mode

1.1 Preparation
Input attenuator
Input terminal
MODE SW
HPF
Output terminal
Data port
AMP ID SW
Others
1,2 Inspection and adjustment

1.2.1 Fan, POWER/PROTECTION LED

Turn on the POWER switch and check that the PROTECTION LED lights up and the POWER LED lights in green and also that
the fan runs at a low speed.

1.2.2 Power ON muting time

Check that at 9±3 seconds after turning on the POWER switch, the muting function is cancelled and the PROTECTION LED
turns off.
1.2.3 Idling current
Ground the input terminal and adjust VR201(A ch) and VR202 (B ch) so that the DC voltage of No.1 to No.2 terminal of CN204
(A ch) and CN203 (B ch) is Vb=0.1±0.05mV.
Also, after all inspections, check the Vb value again and adjust so that Vb=0.1±0.05mV is obtained.
1.2.4 Output terminal DC voltage
Ground the input terminal and measure the DC voltage (Vdc) of the output terminal. It should be Vdc=0±10mV.
(Perform this check within 10 to 20 seconds after turning on the power.)
1.2.5 Gain
Feed 1kHz, -10.0dB sine wave to the input terminal and check that +22.1±0.5dB output voltage is obtained then. This check
should be performed in the PARALLEL mode, too.
1.2.6 Frequency response
· HPF OFF:
Feed 20Hz, 1kHz, 20kHz, -10dB sine wave to the input terminal and measure the output voltage at each time, and then check
that the measured voltage at 20Hz is within 0.0±0.5dB and that at 20Hz is within -0.5±0.5dB as compared with the output
voltage at 1kHz.
· HPF ON:
Feed 40Hz, -10dB sine wave to the input terminal and measure the output voltage, and then check that the measured voltage
is within -3.0±1.0dB as compared with the output voltage at 1kHz in the HPF OFF state.
1.2.7 Total harmonic distortion
Feed 1kHz high grade sine wave to the input terminal and check that the total harmonic distortion is 1% or less when the output
given in the table below is obtained. Make sure to finish this check within 30 seconds.
PC9500N
1000W/8Ω (41.2dB/ch)
(Perform this check in the one channel drive state.)
30
MAX
XLR-3-31 type connector No.2: hot No.1,3: ground
STEREO
OFF
Unless otherwise specified, load resistance: 8Ω, Non-inductive resistance,
power capacity: 1kW or more
Unused
1, 2, 4, 8, 16, T OFF
Unless otherwise specified, both channels set for drive
PC4800N
500W/8Ω (38.23dB/ch)