Sharp VL-H870U Service Manual page 30

VL-H870U
VL-H875U
VL-H890U
6-3-4. Adjustment of system controller and servo circuit
6-3-4-1. Adjustment of playback switching point
b) CHARGING CIRCUIT ADJUSTMENT PROCEDURE
1) Play back the alignment tape (JiGWR5-5NSP)
2) Press the "CONTINUOUS PUSH" and "TEST MODE SELEC-
TION" of adjustment remote controller to set the test mode.
(At this time the numeral of "TEST01" blinks.)
3) Using the "FF" and "REW" keys, select "TEST08", and press the playback key to set the SW-P adjustment mode.
4) After a while the adjustment is completed, and operation stops automatically.
In case of adjustment failure the tape is ejected automatically.
Only in the case when the satisfactory result was not obtained by the adjusting method described above, perform the following
adjustment.
1) Connect each signal to the oscilloscope.
1ch: Video output ..... TL3402
2ch: H-SW-P ............ TL404
GND: GND ................. TL7449
2) Play back the alignment tape (JiGWR5-5NSP)
3) Press the "CONTINUOUS PUSH" and "VCR ADJUSTMENT" of adjustment remote controller to set the VCR adjustment mode.
4) Select the address 30h, set the sync slope of oscilloscope to (–),
adjust the data with "REW" and "FF" so that the interval between
the trigger point and the V sync signal is set to 6H, and fix the data
with the "PLAY" button. (See Figure 6.1.1.)
5) Then, set the sync slope to (+), and ascertain that the interval
between the trigger point and the V sync signal has been set to 6H.
(See Figure 6.1.2.)
6) Keep the STOP key pressed for about 3 seconds to exit from the
adjustment mode.
6-3-5. Y/C circuit adjustment method
Input signal conditions
Video signals generated by a pattern generator are used
to make electric adjustments in a Y/C circuit. Thus this
signal must conform to the standards prescribed for ad-
justment signals.
Use an oscilloscope to check that the video signal is
terminated with a 75 Ω resistor, the amplitude of the sync
signal component, video component and burst signal are
approx. 0.3 Vp-p, 0.7 Vp-p and 0.3 Vp-p, respectively and
that they are flat. The relative level of the burst signal and
the red signal shall be 0.30:0.66.
The color bar used in an electrical adjustment is shown in
Figure A.
* When a pattern generator is not used
Shoot a color bar chart (JiGCHART-4) using a perfectly
adjusted video camera.
A signal from a perfectly adjusted video camera shooting
a color bar chart (JiGCHART-4) can be used as an adjust-
ing signal if the lighting can be set to meet the following
conditions: output (75 Ω terminated), the amplitude of the
sync signal component, video component and burst signal
are approx. 0.3 Vp-p, 0.7 Vp-p and 0.3 Vp-p, respectively.
The relative level of the burst signal and the red signal shall
be 0.30:0.66. This is shown in Figure B.
1. Adjustment of fixed data writing
ADD 67 68
DATA 01 00
Before starting Y/C adjustment, be sure to write the specific data in the addresses listed left.
If the data listed left is written after Y/C adjustment, adjusting values may deviate.
69 6A 6B 6C 6D
02 01 FA 00 00
Measuring instrument
Mode
Adjustment address
Tape
6H
3H 3H
Figure 6.1.1
Approx. 0.7 V
p-p
Approx. 0.3 V
p-p
Figure A Color bar signal produced by a pattern generator
Approx. 0.7 V
p-p
Approx. 0.3 V
p-p
Figure B Color bar signal produced by a video camera
6E 6F 55 66
66 11 FE FE
6-6
Oscilloscope
Playback
30h
Alignment tape (JiGWR5-5NSP)
6H
3H 3H
V sync signal
Figure 6.1.2
White (approx. 100%)
Burst signal
Approx. 0.3 V
Red (approx. 0.6 V
Horizontal sync signal
White (approx. 100%)
Burst signal
Approx. 0.3 V
Red (approx. 0.6 V
Horizontal sync signal
54 65 5C 64
FE FE 70 C0
VL-H870U
VL-H875U
VL-H890U
V sync signal
p-p
)
p-p
p-p
)
p-p