Technics RS-273US - Page 10

ITEM
MEASUREMENT & ADJUSTMENT
REMARKS
Overall Distortion
Equipment :
* Distortion Meter
* AF Oscillator
* ATT
* Oscilloscope
*« Test Tape
(Reference Blank Tape)
«C-RA
1. Test equipment connection is shown below.
LINE IN
Playback
Mode)
Oscilloscope
(Distortion Meter)
Fig. 21
. Supply 1 kHz signal to LINE IN jack and adjust ATT so that
output level at LINE OUT indicates 0.5 V (—6 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, distortion 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” adjustments.
Standard Value: Less than 2.3%
* Record/Playback Mode
* Record Level Control
«MAX
Overall Frequency Response
Equipment:
* VTVM
* AF Oscillator
* ATT
* Test Tape
(Reference Blank Tape)
..C-RA (for Normal)
..C-RF (for CrO2)
. Test equipment connection is shown in fig. 18.
. Tape selector to normal position.
. Load reference blank test tape (C-RA) and place unit into
record mode.
. Supply 1 kHz signal from AF oscillator, through ATT to LINE
IN jack.
. Adjust ATT so that input level is —20dB below standard
recording level.
. At this time, LINE OUT level indicates 0.05 V.
. Record each frequency 40 Hz, 100Hz, 700Hz, 1kHz, 2 kHz,
7kHz, 10kHz and 12kHz (13kHz for CrOz) at the same
level.
. Playback and express in dB the difference between play-
back output level of each frequency based on playback
output level of 1 kHz.
. Make sure that the measured value is within the range
specified in the overall frequency response chart.
Overall Frequency Response Chart (Normal)
+248
0
—2 dB
—5 dB
40 Hz
7kH2 (12 KHz
* Record/Playback Mode
* Record Level Control
«MAX
Note:
Before measuring and
adjusting, make sure of the
playback frequency
response (For the method
of measurement, please
refer to the playback
frequency response).