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VC-780E
" VC-790ET
Adjustment of record current (SECAM)
TP301(Ground: TP302)
Specified value
Cyan level: 16 + 2mVp-p
1. Set the unit in the record mode.
2. Apply a SECAM colour bar signal (stair-step
waveform) to the unit.
ve
3. Observe
the output
of TP301
with
an
oscilloscope and make adjustment in the
following manner.
a)
Connect the ground of the oscilloscope to
" '"7p302 and the signal toTP301.
°°
Note:
i:
TP301 and TP302 are Jocated on the head
amplifier PWB.
b) Adjust R5813
(record chroma
control) so
that the red level should be 16mVp-p as
shown in Fig. 2-20.
Note:
R5813
is located in the system control, servo
PWB.
CYAN
Figure 2-20.
Adjustment of playback equalizer
Alignment tape
(VROCSSV)
Adjusting control
R5813 (Record
44
.
chrominance level control)
1. Set the unit in the playback mode, and playback
an
alignment tape.
2. Observe the output of TP5702 with an
osilloscope,
and
using
T5701
make
the
oscillating width match with the flat portion of
the red and blue test pattern.
TPS702
Adjust the level.
'Figure 2-21.
@ ADJUSTMENT OF NTSC SUB CHROMA CIRCUIT
Adjustment of recording current
Osci lloscope
Recording (LP mode)
Standard colour bar
(stair-case waveform)
TP301(GND at TP302)
R5811 (recording chroma
control)
Measuring
.
instrument
input signal
Test point
Adjusting point
Specification
Redtevel
22 + 2mVp-p
Note:
TP301
and TP302 are located on the head amp
PWB.
1. Place the unit to the record mode.
2. Feed the colour
bar (stair-case
waveform)
signal.
3. Observing the waveform on the oscilloscope
screen, take the following steps.
a) Connect the oscilloscope's GND and SIG
leads to TP302 and TP301, respectively.
b) Adjust R5811 (recording chroma control) to
that the red level be 22 + 2mVp-p as shown
in Fig. 2-22.
22 + 2mVp-p
Figure 2-22.
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