Teac A-450 - DOLBY NR EFFECT MEASUREMENT; DOLBY FM COMPENSATOR EFFICIENCY CHECKS

7-2-6.
DOLBY
NR
EFFECT
MEASUREMENT
1. Load any recordable tape.
2. Place the deck in the RECORD-PAUSE mode.
3. Apply a 1 kHz signal at proper level.
4
for the following measurements.
Set the DOLBY NR switch to IN.
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reference level.
7. Reset the DOLBY NR switch to OUT.
8. Repeat the above procedures (steps 3 — 6), with the '
following exceptions.
Applied test signal:
Reading on VTVM:
10 kHz
3.2 mV (-48 dB)
(Reference level)
Variation from reference: 10dB+1 dB
Specification:
Variation from reference at 1 KHz: 5dB+1dB
Variation from reference at 10 KHz: 10 dB+ 1 dB
Adjust the Attenuator for 10 mV (-38 dB) on the |
VTVM. Note this reading for temporary reference level
6. Make sure the reading reduces 5 dB + 1 dB from the
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i
CONNECTION: See Fig. 7-8
SWITCH & CONTROL SETTING:
BY See |
FM/COPY ~ SOURCE
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a ENR:
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T-472
OUTPUT Control: Specified Control Setting (See 7-1-2)
LINE Control: Specified Control Setting (See 7-2-2)
MIC Control: Minimum Setting
NOTE
Do not move any control setting above, though these
i control settings are ineffective in these checks. See
‘ 7-2-3 NOTE for details.
7-2-7. DOLBY FM COMPENSATOR
EFFICIENCY CHECKS
1. Load any recordable tape.
2. Place the deck in the RECORD-PAUSE mode.
3. Apply a 400 Hz signal at —14 dB (154 mV).
4. Read the VTVM indication.
Note this reading for temporary reference level for the |
following measurements.
5. Apply a 10 kHz signal at —14 dB.
6. Make sure the reading raises 8 dB + 1 dB from the |
reference level. i
7. Set the SOURCE switch to NORMAL.
8. Repeat the above procedures (steps 3 — 5).
9. Make sure the reading of the 10 kHz signal is within + |
1 dB from temporary reference level of 400 Hz signal. ©
Specifications:
Variation
from
reference
at
FM
(SOURCE
switch)
:
8dBi1dB
Variation
from
reference
at
NORMAL
(SOURCE
switch):
OdBt
1
dB
| CONNECTION
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OSCILLOSCOPE i
‘
i
4
i
5
DECK
under TEST
Fig. 7-10 Connection
SWITCH & CONTROL SETTING:
Cnr, eS
LEY eo)
FM/COPY — SOURCE
7-473
OUTPUT
Control:
Specified
Control
Setting
(See
7-1-2)
LINE
Control:
Specified
Control
Setting
(See
7-2-2)
:
MIC
Control:
Minimum
Setting
:
NOTE
Do
not
move
any
control
setting
above,
though
these
controls
settings
are
ineffective
in
these
checks.
See
7-2-3
NOTE
for
details.
21