Marantz SR620 - Page 8

ALIGNMENT POINTS
6. CX CIRCUIT ALIGNMENT AND MEASUREMENT PROCEDURE
6.1 Alignment Procedure
(a-1) Output Level Adjustment
1
3.
. Set the input VR (RD53) to mechanical center.
2.
Apply a 1 kHz sine wave signal to the Phono input
(appr. 4 mV).
Attenuate the input audio signal generator until both
CX CAL indicator LEDs (QZ01, QZ02) are out.
. Check the DC voltage between test points JDO5 (+)
and JDO6 (GND) at this time. Voltage must be 5 V
40.5V.
. Next, adjust the semi-fixed RD33 (L. ch.) and RD34
(R. ch.) for equal output level at TAPE OUT with the
CX switch (SD51) in ‘‘on” and “off’’ positions.
(a-2) DC Offset Adjustment
1
. After performing the adjustment described in a-1),
adjust the semi-fixed VR RD27 (L. ch.) for a DC voltage
reading of O V between test points JDO7 and JDO6,
with the CX switch (SD51) in the “on” position.
. In the seme way, adjust the semi-fixed RD28 (R. ch.)
for a DC voltage reading of 0 V between test points
JDO8 and JDO6G.
. Next, check the left channel DC voltage again, and
perform re-adjustment if a change has occured.
6.2 Measurement Procedure
Measurement of Input Vs. Output Level
. Apply a 1 kHz sine wave signal to the Phono input and
attenuate the input signal until both CX CAL LEDs are
out. {Input VR at mechanical center).
. Assume the TAPE OUTPUT level at this time to be OdB.
Next, attenuate the input signal by 10 dB.
. Measure the TAPE OUTPUT level at this time, and
confirm that it is -20 dB+5 dB.
. Next, attenuate the input signal to —30 dB (—10 dB
+ —20 dB total of —30 dB).
. Measure the TAPE OUTPUT level at this time, and
confirm that it is —50 dB+5 dB.
THD Measurement
. Apply a 1 kHz sine wave signal to the Phono input and
attenuate the input signal until both CX CAL LEDs are
out. (Input VR at mechanical center.)
. Next, raise the input signal level by 6 dB. At this time,
THD at the TAPE OUTPUT must measure 0.5% or
less.