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122
OSCILLOSCOPE
OSCILLATOR
AMP
SPKR
flC.
VOLTMETER
UNIT
under TEST
Fig. 7-5
7-10. CHANNEL SEPARATION
1) Connect the measu ring instru ments as shown
in Fig. 7-5.
For the right channel, connect only the
VTVM. For the left channel, install a 1-kHz
bandpass filter between the OUTPUT termi·
nal and the VTVM.
2) With a 1-kHz input signal, obtain the standard
setting according to procedures 2) - 6) of
7-5. to check the record/reproduce level.
3) Make a stereo recording applying the input
signal only to the left channel and no signal to
the right channel.
4) Rewind the tape to the start of the recording
and play it.
Measure the output
,
l evels of both channels.
(The right channel will contain the recorded
signal and the left channel wil
'
l contain com
ponents wh ich have leaked from the right
channeL).
5) Calculate the difference in
level,
between
the
two channels. This value should be more than
35dB.
7-11. LED LIGHTING OF VU METER
(PEAK indicator)
According to procedures 1) - 5) of 7-5., adjust
until the VU meter indicates 0 VU.
1) Confirm that the LED lights when the input
level is increased by 8 dB from -14 dBV and
does not light when the input level is in
creased by 7 dB from -14 dBV.
2) If the lighting level is not satisfactory, adjust
semi-fixed resistors R72/R82.
7-12. DOLBY NOISE REDUCTION EFFECT
1) Connect the measuring instruments as shown
in Fig. 7-3.
2) Set the EQ and B lAS switches to match the
blank tape used and the MONITOR switch to
SOURCE.
50
3) Load the blank tape and put the deck in the
record/pause mode.
4) Apply a -14 dBV/1 kHz signal to the LI N E 1
or 2 term inal.
5) Adjust the INPUT (LEFT/RIGHT) level con
trol so that the VU meter indicates +3 VU.
Also adjust the OUTPUT level control so that
the OUTPUT terminal level is -7 dBV.
6) Set the MONITOR switch to TAPE. Record a
-37 dBV/1 kHz signal on the blank tape,
decreasing the input level by 23 dB and
reproduce the signal.
7)
Wh~le
recording and reproducing, switch the
N R SYSTEM switch between N R and OUT to
check that the change in level is between 3
and 8 dB.
8) Check the level when a -47 dBV/10 kHz
signal is recorded and reproduced. The values
are shown in the following table.
Measure the OUTPUT terminal level, increas
ing the sensitivity of the VTVM by an amount
equ ivalent to the decrease in the input signal
level.
I nput signal
Change in Output level
-37 dBV. 1 kHz
between 3 and 8 dB
-47 dBV, 10 kHz
between 8 and 12 dB
7-13. DOLBY HX EFFECT
Follow the same procedures as in 7-12. DO LBY
NR EFFECT up to item 3).
1)
Apply a -14 dBV/400 Hz signal to the LINE
1 or 2 terminal.
2) Adjust the INPUT (LEFT/RIGHT) level con
trol so tha.t the VU meter indicates 0 VU.
Also adjust the OUTPUT level control so that
the OUTPUT terminal level is -10 dBV.
3) Set the N R SYSTEM switch to HX and check
the response, changing the input signal fre
quency.
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