JVC KS-FX621 Service Manual page 20

KS-FX621
QQ
3 7 63 1515 0
Item
Conditions
1. Head
Test tape:
azimuth
SCC-1659
adjustment
VT703(10kHz)
TE
L 13942296513
2. Tape speed
Test tape: VT712
and wow
flutter
confirmation
3. Play back
Test tape: VT724
frequency
response
www
confiramation
(63Hz / 1kHz / 10kHz)
1-20 (No.49825)
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Adjustment and Confirmation methods
Head height adjustment
Adjust the azimuth directly. When you
adjust the height using a mirror tape,
remove the cassette housing from the
mechanism chassis. After installing the
cassette housing, perform the azimuth
adjustment.
1. Load the SCC-1659 mirror tape. Adjust with
height adjustment screw A
adjustment screw B so that line A of the
mirror tape runs in the center between Lch
and Rch in the reverse play mode.
2. After switching from REV to FWD then to
REV, check that the head position set in
procedure 1 is not changed. (If the position
has shifted, adjust again and check.)
Adjust with azimuth adjustment screw B so
3.
that line B of the mirror tape runs in the
center between Lch and Rch in the forward
play mode.
Head azimuth adjustment
1. Load VT724 (1kHz) and play it back in
the reverse play mode.
Set the Rch output level to max.
2. Load VT703 (10kHz) and play it back in
the forward play mode. Adjust the Rch
and Lch output levels to max, with
azimuth adjustment screw B. In this case,
the phase difference should be within 45 .
Engage the reverse mode and adjust the
3.
output
adjustment screw C.
(The phase difference should be 45 or
more.)
When switching between forward and
4.
reverse modes, the difference between
channels should be within 3dB. (Between
FWD L and R, REV L and R.)
5. When VT721 (315Hz) is played back,
the level difference between channels
should be within 1.5dB.
Check to see if the reading of the F, counter /
1.
(3kHz) wow flutter meter is within 3015Hz to 3045Hz
(FWD/ REV), and less than 0.35% (JIS RMS).
In case of out of specification, adjust the
2.
motor with a built-in volume resistor.
1. Play test tape VT724, and set the volume
position at 2V.
(1kHz)
VT739
2. Play test tape VT739 and confirm.
1kHz / 10kHz: -1
x ao
1kHz / 63Hz: 0
. i
3. When 10kHz is out of specification, it will be
necessary to read adjust the azimuth.
The tuner section is of an adjustment-freedesign. In case the tuner is in trouble, replace the tuner pack.
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and azimuth
Q Q
3 6 7
level to max, with azimuth
3dB,
u163
y
3dB,
2 9 9 4
8
S.Values
Head shield
The head is at low position
during.
Head shield
The head is at High position
during REV.
Output
level:
Maximum
PBHead
FWD Adj B
1 3 1 5 0 5 8 2 9
HEIGHT Adj A
REV Adj C
phase
(0 )
Tape speed: Built-in volume
3015Hz resistor
to 3045Hz
Wow
flutter: less
than 0.35%
Speaker out
1kHz / 63Hz
: 0 3db
m
1kHz / 10kHz
: -1 3db
co
.
2 8
9 9
Adjust
A line
B line
9 4 2 8 9 9
(45 )