Advertisement
DOLBY
NR
ADJUSTMENTS
e
Main Component Locations and Connections
o™
«-_™
SFR303
SFR301
(3049)
(302)
OOLBY-NR
CIRCUIT
BOARD
PB
ee
lS
am
—*
AM
o
P
'
REC/PB
: Bei
1
o
REC
$
OPEN
oP
VTVM
GATE
oc2av
!
oo
0 O-
SHORT
ON
DOLBY-NR
eel
Ie
pe
OFF
1)
Remove
Dolby NR circuit board from set and connect
as shown
in drawing.
2)
Turn SFR301
(302) and SFR303
(304)
fully in the
directions shown
by arrows.
3)
Position switches as follows.
REC/PB:
PB
GATE:
OPEN
DOLBY-NR:
OFF
4)
Apply
400Hz
signal
and
adjust
attenuator
so that
output becomes 7.6mV, then read attenuator value.
Rating:
—49dB +1dB
5)
Set
REC/PB
switch
to REC
and confirm
output
level
difference of +0.25dB. Next at frequencies of 100Hz,
1kHz
and
10kHz,
confirm
an output
level difference
of +1dB.
6)
Position switches as follows.
REC/PB:
PB
GATE:
SHORT
DOLBY-NR:
OFF
7)
Apply
5kHz
signal
and
adjust
attenuator
so
that
output becomes
7.6mV, then read attenuator value.
Rating:
—49 +1dB
Next
set
DOLBY-NR_
switch
to
ON
and
adjust
SFR303 (304) for 2.4mV output.
8)
At the above (step 7) condition, set GATE
switch to
OPEN and adjust
SF R301 (302) for 3mV output.
9)
After
adjusting,
apply
locking
compound
to trimmer
resistors.
GIG. GEN
10
AIWA
ELECTRICAL
MEASUREMENTS
PREPARATIONS
FOR
MEASURING
Required Equipment
® Low frequency oscillator
® Variable resistance attenuator
® Oscilloscope
® 6002 and 100k2 resistors
® Distortion meter
® Wow
meter
@ 1kHz bandpass filter
@ Test tapes:
TTA-116/TTA-114/TTA-119D (CrO,)/TTA-
119E (Fe-Cr)/TTA-119A (LH)
Connection
WOW METER
MIC. JACK
S!IG.GEN
ATT
<~—
LINE OUT
100KQ
Bandpass filter
eM
Measuring Cautions
1)
Before
measuring,
demagnetize
rec/play
and
erase
heads
with
head
eraser
and
clean
heads
with
gauze
moistened
in alcohol.
2)
Set playback volume to maximum.
3)
Standard inputs (OdB = 0.775V)
MIC jack
65dB
LINE-iIN
20dB
4)
Connect 100k load resistor to LINE OUT.
Playback Output
Play test tape TTA-161 and measure output level.
Rating:
1.03V +0.5dB
Recording/Playback Distortion
Apply 400Hz
signal via MIC jack and adjust attenuator for
OVU
indication
on set VU meter. Record this signal on test
tape and measure playback distortion.
Ratings:
TAPE
Test
T
ers
SELECTOR
Distortion
TTA-119D
(CrO tape)
TTA-119E
(Fe-Cr tape)
| Fe-Cr
' | TTA-119A
(LH tape)
LH-NORMAL |} Less than 1.5%
Less than 2.5%
Less than 1.0%
Advertisement
