JVC KD-A11 - Page 9

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Main Adjustments
[1]
1.
[11]
Equipment
and
measuring
instruments
used
for
adjustment.
Electrical adjustment
1) Electronic voltmeter
2) Audio frequency oscillator
(range; 50-20 kHz and output 0 dB with impedance
600 &2)
3) Attenuator
4) Standard tapes for REC/PB
SONY CS-30 — FeCr tape
BASF T308S — NORMAL tape
BASF C401R — CrO2 tape
SCOTCH METAFINE — METAL tape
5) Reference tapes for playback (JVC Test Tape)
VTT-658 (for head azimuth adj.)
VTT-656 (for motor speed, wow flutter adj.)
VTT-664 (for Reference level 1 kHz)
VTT-675N (for playback frequency response)
6) Resistors
100 22 (for measurement of the bias current)
600 {2 (for attenuator matching)
or equivalent
. Mechanical adjustment
1) Gauge for checking the head position.
2) Torque gauge
3) Blank tape (C-120) for tape running checker.
Adjustment and repair of the mechanism
Audio Freq. Osc.
La
KD-A11A/B/C/E/J/U
Electronic
Voltmeter _,
Attenuator
oe
S304 “13 6000
OUT/PUT
(Adjust
the
mechanism
or
confirm
that
it is
in
normal
Operating
condition
prior
to
the
adjustment
of
the
electrical
circuit.)
Adjusting record/
playback head
position
Adjusting erase
head height
. Connect an electronic voltmeter to
the LINE OUT terminals.
2. Play back the VTT-658 test tape.
3. Adjust the head angle with the
screw (@) until the reading of the
electronic voltmeter becomes max-
imum for both channels.
4. After adjusting, set the screw with
screw bond.
Tape-to-head contact adjustment
1. Turn the adjusting screw for
aligning the erase head until it stops.
Then, turn the screw in the re-
verse direction by 180° (a % revolu-
tion).
2. Employ a special cassette (C-120)
© from which parts to the casing,
where the erase head, record/play
back head and capstan engage, has
been cut away. Perform tape trans-
port with the cassette tape. Adjust
the screw until the tape runs in
the center of the egase head tape
guide.
3. Check it again with a BASF C401R-
CrOQ2 tape.
Checking method:
Record a 400 Hz or 1 kHz signal
with OVU+20dB. Erase the record-
ing. Check if the erasing is satisfac-
torily performed.
4. After adjustment, apply screw bond
on the adjusting screw to prevent
its loosening.
Proper
Tape guide
EF
Improper
ct
Screw
®
Maximum
|
1.
If
the
head
is
worn,
disconnected
or
exceedingly magnetized so as not to
provide the necessary characteris-
tics, replace it with a new one.
After replacement, the head posi-
tion adjustment as well as the play-
back level adjustment, the bias cur-
rent adjustment and the recording
level adjustment are all necessary.
2. If the output difference between
the left and right channels exceeds
3—4 dB, the head is defective.
Replace it with a new one.
Be sure to perform this adjustment
after replacing the erase head.