Sharp VC-780E

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VC-780E
" VC-790ET
Adjustment of record current (SECAM)
:
Measuring.
1
Oscil
at
“ee
|
instrument
ceases
am
Input
signal
Colour
bar
signal
|
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.