Technics RS-630USD

11
Overall distortion
Equipment:
* Distortion meter
+ AF oscillator
* ATT
+ Oscilloscope
* Test tape
(reference blank tape)
++ C-RA
C-RA for Normal
C-RF for CrOz
MEASUREMENT & ADJUSTMENT
When standard recording level is supplied.
Test equipment connection are shown in fig. 21.
LINE OUT
ATT Record mode VTVM
Fig. 21
AF oscillator Oscilloscope
Set the peak level check switch to the “IN” position
Supply a 1kHz signal from the AF oscillator, through the ATT, to the
LINE IN Jack
_ Adjust the ATT so that the monitor level at LINE OUT becomes 0.42 V.
Adjust VR13 (L-CH) and VR14 (R-CH) so that the VU meters indicate
(See fig. 22)
Si ith
OVU.
l
Calibrations for “IN”
position of peak check switch.
Calibrations for “OUT”
position of peak check switch.
Balance of left and right level meters
9, Set the peak level check switch to the “OUT” position
10. Then adjust VR18 for L-CH so that left and right VU meters show
the same indication.
1. Test equipment connection is shown in fig. 23.
LINE IN
R/P head
ATT 6000 Record
mode Test tape
Playback mmole i
re e
Test tape J‘
son
meter
Fig. 23
. Supply 1kHz signal to LINE IN and adjust ATT so that output level
at LINE OUT indicates 0.42 V (—7 dB).
. Make recording.
. Playback and measure distortion factor of output signal.
. When the distortion factor does not satisfy the standard, check the
bias current. When the bias current is lower than standard, distor-
tion will increase.
Care should be exercised in the adjustment because the bias current
also has an influence on the overall frequency response. Refer to
“The overall frequency response” and “The bias current adjustment”.
Standard Value: Less than 2.3 % (Normal)
Less than 3.3% (CrOz)
REMARKS
* Input selector--
“LINE IN
* LINE IN level control
* Input selector:
-LINE IN