Teac A-7300RX - Page 26

10-29
DECODER
OPERATION
CHECK
Depress
DECODER
SW
to
IN,
1.
Change
the
Input
signal
frequency
to
100
Hz,
The
SOURCE/TAPE
output
level
should
read
—3
dB
+]
dB
(615
mV--488
mV).
2.
Change
the
Input
signal
frequency
to
10
kHz,
The
SOURCE/TAPE
output
level
should
read
+1.4
dB
+]
dB
(730
V—580
V).
3.
Decrease
Input
level
to
—38
dB
(9.75
mV)
and
check
that
OURCE/TAPE
output
level
reads
—68
dB
(345
mV
—274
mV).
Increase
Input
level
to
+2
dB
(975
V)
and
check
that
SOURCE/TAPE
output
level
reads
+12
dB
+1
dB
(12.6
V-19.9
V).
_
With
these
condition
distortion
should
be
less
than
0.5%.
Set
ENCODER
SW
to
IN.
.
Remove
Input
signal
and
check
that
SOURCE/TAPE
output
noise
level
is
—85
dB
or
less.
-
an
fon
10-30 dbx SINGLE SINEWAVE RESPONSE
CHARACTERISTICS
1. Depress the ENCODE and DECODE pushbuttons and
then run OVERALL FREQUENCY RESPONSE Section
10-19.
2. Check also for reading within the Response Limits chart.
See Fig. 10-20.
- for Input Level
+
FS
°
1
2
RESPONSE IN 6B
&
et ET
Low (7-
4
RESPONSE IN 48
&
K
FREQUENCY IN Hz
Fig.
10-20
dbx
Single
Sinewave
Response
Limits
Chart
10-31 dbx CHANNEL SEPARATION
1. Repeat Section 10-22 with ENCODE and DECODE push-
buttons depressed.
2. Separation should be 65 dB or more at 1 kHz.
10-32 dbx SYSTEM OVERALL DISTORTION
CHECK
1. Repeat Section 10-24 with ENCODE and DECODE push-
buttons depressed.
2. Distortion should be 0.8% or less at 1 kHz
(Specified level)
3% or less at 1 kHz (+20 dB level)
10-33 dbx OVERALL SIGNAL-TO-NOISE
RATIO CHECK
1. Repeat Section 10-23 with ENCODE and DECODE push-
buttons depressed.
2. The noise level as indicated on the VTVM should be
reading 60 dB or more (both HIGH and LOW speeds).
10-34 dbx IN/OUT LEVEL DIFFERENCE
CHECK
1. Apply specified Input signal 400 Hz, —8 dB (308 mV).
2. During recording and playback depress and release
ENCODE qnd DECODE pushbuttons.
3. Difference in output level should be 2 dB or less.
27