Sharp VC-90ET - Page 39

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ADJUSTMENT
OF
SECAM
SUB
CHROMA
CIRCUIT
Adjustment
of
record
mode
Measuring
:
inode
selection
Input
signal
Colour
bar
signal
Measuring
Adjustin
;
opel
T5703
(bell
filter)
Specified value
1. Set the unit in the record mode.
2.
Apply
a
SECAM
colour
bar
signal
to
the
unit
and
record
it.
3.
Observe
the
output
of
TP5706
with
an
osilloscope,
and
adjust
15703
so
that
the
chroma
signal
becomes
flat
as
shown
in
Fig.
2-
15.
TP5706
‘eames
<
m
-
c
°
2
ears’,
Figure 2-15.
Adjusting of sync gate in the record mode
Oscilloscope
Colour bar signal
Video output terminal
R5815 (Sync gate adj.
T1: 1.5psec
To: 5.6psec
1. Apply a SECAM colour bar signal to the unit
and record it.
2. Connect an oscilloscope to TP5702 and video
output terminal and make sure that the chroma
signal output is just as shown in Fig 2-16.
3. Adjust R5814 and R5815 so that the intervals T1
and T2 in the waveform of the output at
TP5705 and those in the video output
waveform should be corresponding to each
other.
Measuring
instrument
Mode selection
Input signal
Measuring point
Adjusting control
Specified value
aa
VC-90ET
TPS707
MONVTRA
——— Video Oulput
Figure 2-16.
Adjustment of recording equalizer (T5702)
1. Adjust T5702 so that the output at point @
should be as shown in Fig. 2-17.
TP5707
MOT13A
Figure 2-17.
Adjustment of record current (SECAM)
Oscilloscope
[Modeselection | Recordmode
Input signal Colour bar signal
Measuring
instrument
TP301 (Ground : TP302)
R5813 (Record chrominance
level control)
Cyan level : 20 + 2mVp-p
1. Set the unit in the record mode.
2. Apply a SECAM colour bar signal (stair-step
waveform) to the unit.
3. Observe the output of TP301 with an
oscilloscope and make adjustment in the
following manner.
a) Connect the ground of the oscilloscope to
TP302 and the signal to TP301.
Note :
- TP301 and TP302 are located on the head
amplifier PWB.