Technics RS-676US - Page 17

ITEM
MEASUREMENT & ADJUSTMENT
REMARKS
Overall - Frequency Response
Equipments:
* VTVM
* AF Oscillator
* ATT
* Test Tape
(Reference Blank Tape)
...C-RA for Normal
...C-RF for CrO2
Note:
Before measuring and adjusting, make sure of the playback
frequency response (For the method of measurement, please
refer to the playback frequency response).
1.
2.
3:
Test equipments connection is shown in fig. 23.
Load reference blank test tape and place UNIT into record
mode.
Supply 1 kHz signal from AF oscillator, through ATT to LINE
IN.
. Adjust ATT so that input level is —20dB below standard
recording level (standard recording !evel=O VU).
. At this time, LINE OUT level indicates 0.42 V.
. Record each frequency 40Hz, 100Hz, 7O00Hz, 1 kHz,
2kHz, 7 kHz, 10kHz and 12kHz (13kHz for CrOz) at the
same level.
. Play back 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)
+2 0B +24B
0 0 dB
—2
0B
—3
4B
—5 B Lite 2.4 7 kHz | 12 KHz
10
40 He kHz
Fig. 26
. Set the tape selector switch to CrOz position.
. Measure as Same as manner above.
. Make sure that the measured value is within the range
specified in the overall frequency response chart for CrOz2
tape below.
Overall Frequency Response Chart (Croz)
+2 0B
0dB
TkHz 2 kHz
Fig. 27
MPX Filter out position, normal tape
In case the line output deviation is not within the standard on
the basis of 1 KHz=O dB after measuring the overall frequency
response:
a
\f the frequency response varies from about 4~6kHz in
the middle-frequency range and becomes out of standard
in the high-frequency range, adjust it using the bias cur-
rent.
. If the frequency response is flat in the middle-frequency
range and varies excessively in the high-frequency range,
adjust it using the peaking coil for recording equalization.
Adjustment 1—Using bias current
4kHz 6kHz 8 kHz 12kHz
—$—$———
Fig. 28
* Record/Playback Mode
* Record Level Control
..MAX.
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