JVC PC-5 L - Cassette Amplifier Adjustment

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,
be
performed,
however,
only
checking
is
sufficient
with
3,...
Perform
this
adjustment
with
the
ANRS
switch
set
steps
other
than
those.
to
OFF.
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.