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PC-5 L/LB
|
4.
Adjustment Procedure of Cassette Amplifier
In the steps marked by an asterisk (*), adjustment should
Adjustment should be performed in the order of steps 1, 2,
No. 1443
Adjusting
playback
level
Playback
frequency
response
Level
indicator
sensitivity
Adjusting
recording
level
Checking
back fre-
quency
response
Response
(dB)
1. Play back the VTT-664 Reference
VR101, | —8 dBs
tape (1 kHz) with the tape select
201 | (0.3 V)
switch set to the SF/NORM
posi-
tion.
. Adjust
VR101
and VR201
until
the LINE OUT becomes about —8
dBs.
Playback
test
tape
VTT-675N
(1
kHz, 10 kHz).
Check to see if the 10 kHz signal and
1
kHz
signal
gains
become
flat
0.5+2dB
response.
at 10 kHz
. Set the cassette deck to its record-
oOVU
ing mode.
. Apply a 1 kHz, approx. —10 dBs
signal to the LINE
IN terminals.
. Adjust the recording level controls
until the signal is available at —8
dBs at the LINE OUT terminals.
. Check to see if the indicator con-
forms 0 VU.
Reference
frequency;
1 kHz
. Apply a 1 kHz, approx. —10 dB
VR102
| —8dBs
signal to the LINE
IN terminals.
202
Adjust the recording level controls
until the signal is available at —8
dBs at the LINE OUT terminals.
. After checking to see if the in-
dicator
become
QO, record
the
signal
applied
to
both
left and
right channels using normal tape.
. Play back the recording part. Per-
form
the recording signal adjust-
ment with VR102 and VR202 so
that the indicator become 0.
Record
1 kHz, 50 Hz and 12.5 kHz
Reference
record/play- | signals at an input level of O VU to
frequency;
—20 dB.
1 kHz
Play back the tape.
Check to see that the 50 Hz and 12.5
kHz
signal
output
deviations
fall
0+3dB
within the standard range, using the
at 50 Hz
1 kHz signal output as a reference.
0+3dB
at 12.5 kHz
Increase in high frequencies
(with a small bias current)
Optimum level
Decrease in high frequencies
(with a larger bias current)
1kHz
12.5kHz
Frequency (Hz)
— 24 —
Remarks
This adjustment becomes necessary
when
a change
in playback
level
results
(for example,
due
to head
replacement).
ANRS : OFF
TAPE SELECT : SF/NORM
Perform
the adjustment
when the
parts are replaced.
The
level
difference
between
left
and
right channels for SF/NORM
tape, chrome
tape and metal tape
should
be less than 1 dB (1 VU).
Perform
the
adjustment
using
a
normal
tape,
level
difference
be-
tween
recording
and
playback for
SA/CrO,, and metal
tapes, should
be less than
1.5 dB, and that be-
tween
left
and
right
channels
should also be less than 2 dB.
This checking should be performed
for normal, chrome and metal tapes
and for both right and left channels.
1. Bias
current
adjustment
for a
cassette deck should generally be
performed
referring
to the
re-
cord/playback
frequency
re-
sponse.
This is because the fre-
quency
response
of a cassette
deck depends more greatly upon
the bias current than does that
of an open reel deck.
. If the
bias current
is not
pro-
perly
adjusted,
the record
and
playback characteristics
become
as shown left.
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