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7.
Overall level characteristics, distortion rate check
Mode
Signal
Measurement Point
Measuring Instrument
Specified Value
Self record/playback
400Hz, -7.5 dBs:
Left audio input terminal [right]
No signal:
Right audio input terminal [left]
Left audio output terminal [right]
Audio level meter and distortion
meter
Level:
-7.5
±
2
dBs
Distortion rate: Below
0.8%
(Note
2)
Note:
1) The [] contains points to be measured when checking
the right channel.
2) Value when the 200Hz to 6 kHz band pass filter is
used.
200Hz
6kHz
18
dB/OCT
Fig. 9-26.
Checking method:
Order
2
3
4
Procedure
Input the 400Hz, -7.5 dBs signal only to the left
audio input terminal fright].
Note: Be sure to insert the shorting plug to the
tenninal of non-signal input.
Record the signal.
Remove the input signal, and playback the
recorded section.
Check that the 400 Hz signal level of the left audio
output tenninal [right] is
-7.5±2
dBs, and that the
distortion rate is below
0.8%
(Note
2)
8.
Separation check
Mode
Self recording/playback
No signal:
Signal
Left audio input tenninal [right]
400Hz, -7.5
dBs:
Right audio input tenninal [left]
Measurement Point
Left audio output terminal [right]
....
.....
Audio level meter
Measuring Instrument
(Use an IHF-A curve auditory
correction filter)
Specified Value
Below
-27.5
dBs
Note:
The [ ] contains points to be measured when checking the
right channel.
Checking method:
Order
2
3
4
5
Procedure
Insert a shorting plug into the left audio input
terminal fright], and input a I kHz, -7.5 dBs signal
only to the right audio input terminal [left].
Record the signal.
Remove the input signal.
Play back the recorded section.
Check that the cross talk level (1 kHz) of the left
audio output terminal [right] is below -27.5 dBs.
9.
Overall noise level check
Mode
Self record/playback
No signal:
Signal
Left and right audio input
tenninals
Measurement Point
Left audio output terminal.[ right]
Audio level meter
Measuring Instrument
(Use an IHF-A curve auditory
correction filter)
Specified Value
Below
-67.5
dBs
Note:
The [
J
contains points to be measured when checking the
right channel.
Checking method:
Order
2
3
4
5
Procedure
Insert the shorting plug to both the left and right
audio input terminals.
Record.
Remove the shorting plug.
Play back the recorded section.
Check that the noise level of the left audio output
tenninal [right] is below
-67.5
dBs.
-251-
9-8.
ARRANGEMENT DIAGRAM FOR ADJUSTMENT PARTS
DD-55 BOARD (COMPONENT SIDE)
2
~
z
(.)
40
39
-252-
DD-55 BOARD (CONDUCTOR SIDE)
36
26
37824
IC460
46
13
1
12
04640
12
1
s
13
24
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