Black Level; Sub Contrast - Mitsubishi WS-48315 Service Manual

[Video Circuit]

7. Black Level

Measuring
-----
Instrument
Test Point
-----
------
Ext. Trigger
Measuring
------
Range
Input Signal
Monoscope
Input Terminal
Video Input
CIRCUIT ADJUST MODE
Activate ........ MENU-0-3-5-7
Function .................AUDIO
Item No. .................VIDEO
Adjust Data ...........ADJUST
Save Data .... .........ENTER
Exit ..............MENU (twice)
[Video Circuit]

8. Sub Contrast

Measuring
DC ma meter
Instrument
DT connector pins 7 & 8
Test Point
------
Ext. Trigger
Measuring
-----
Range
Input Signal
Grayscale
RF Input
Input Terminal
CIRCUIT ADJUST MODE
Activate ........ MENU-0-3-5-7
Function .................AUDIO
Item No. .................VIDEO
Adjust Data ...........ADJUST
Save Data .... .........ENTER
Exit ..............MENU (twice)
Sub Contrast Current Alignment
WS-48315 / WS-55315
520 ±10ua
MODELS: WS-48315 / WS-55315 / WS-65315
Purpose:
To set the black level of the picture.
Symptom:
Excess or insufficient brightness.
1. Supply a Monoscope signal to a Video Input.
2. Activate the Adjust Mode, Video Chroma Function.
3. Adjust Item "2 SBRT" so the 0% and 10% black levels on the gradation scale
are the same.
4. Press ENTER to save data.
7. Exit the Service Mode.
NOTE: Item 2 SBRT should be no more than "21".
40% 30% 20% 10%
50% 0% 0% 0%
60% 70% 80% 90%
GRADATION SCALE
To set overall beam current to its' optimum level.
Purpose:
Symptom:
Excess or insufficient contrast.
Note: Activate the Expand mode (full screen).
1. Supply a Grayscale signal to a RF Input.
2. Activate the Adjust Mode, Video Chroma Function.
3. Select Item "1 SCT", signal level automatically reduces.
4. Connect a 3ma DC meter between DT connector pins 7 and 8. Positive lead to
pin 7.
5. Adjust Item "1 SCT" for the current given in the table below.
6. Remove the meter.
7. Press "ENTER" to save data.
8. Exit the Service Mode.
WS-65315
550 ±10ua
Page 33