Yamaha XP-7000 Service Manual page 36

XP7000/XP5000
I
INSPECTIONS
1. Applicable range
• Applicable to the power amplifiers XP7000/XP5000.
* For the details of adjustment points, refer to "Switches and Adjustment Points" (p. 41).
2. Preparation for STEREO/PARALLEL mode
Attenuator
Input terminal
MODE switch
GAIN switch
HPF switch
Load resistance
• Unless otherwise specified, use above settings for all inspection items of the STEREO/PARALLEL mode. When any setting
has been changed, be sure to reset it back to the above setting before testing other items.
• Unless otherwise specified, use a high grade sine wave for the input signal.
• Unless otherwise specified, keep both channels in the drive mode.
• The unit used for analog I/O level is 0 dBu=0.775 Vrms.
3. Inspection and Adjustment
3.1 Power ON muting time and POWER LED, PROTECTION LED
Turn on the power and check that POWER and PROTECTION LEDs light up.
Turn on the power and check that PROTECTION LED turns off in 2.5 ± 1 seconds.
3.2 Fan and TEMP LED
Short-circuit 2 jumper cables within the "FAN-C" marked frame on the PS circuit board and check that the fan runs. Also short-
circuit 2 jumper cables within the "TM-C" marked frame and check that TEMP LED lights up.
3.3 Idling current
Ground the input terminal and adjust VR201 so that the DC voltage Vb between the pins 1 and 2 of CN101 on the PA unit
becomes 0.275 ± 0.025 mV. After all inspections, adjust the Vb again so that it becomes 0.5 ± 0.1 mV. Perform this adjustment
on both channels.
3.4 DC voltage of output terminal
Ground the input terminal and measure the DC voltage Vdc at the output terminal. Check that the measured value is 0 ± 75
mV.
3.5 Gain
3.5.1 Nominal gain
Input a 1 kHz, -10.0 dBu sine wave signal to the input terminal and check that +22.0 ± 0.5 dBu output voltage is obtained.
3.5.2 GAIN switch
Set the GAIN switch to 26 dB.
Input a 1 kHz, -10.0 dBu sine wave signal to the input terminal and check that +16.0 ± 0.5 dBu output voltage is obtained.
Next, set the GAIN switch to +4 dBu.
Input a 1 kHz, -10.0 dBu sine wave signal to the input terminal and check that the output voltage obtained is as specified in the
table below.
XP7000
+25.7 +/- 0.5 dBu
36
: "0" (MAX) (both channels)
: XLR connector 2PIN-HOT/3PIN-COLD/1PIN-GND
: STEREO
: 32 dB
: OFF (both channels)
: 8 ohms +/- 1%
XP5000
+24.2 +/- 0.5 dBu