Black Level & Sub Contrast - Mitsubishi Electric WS-73513 Service Manual

MODELS: WS-48513 / WS-48613 / WS-55513 / WS-55613 / WS-55813 / WS-65513 / WS-65613 / WS-65713 /
WS-65813 / WS-73513 / WS-73713
[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
Ite m N o . .................VIDEO
Adjus t Data ...........ADJUST
Save Data .... .........ENTER
Exit ..............MENU (twice)
[Video Circuit]
8. Sub Contrast
Measuring
DC ma meter
Instrument
Test Point DT connector pins 7 & 8
------
Ext. Trigger
Measuring
-----
Range
Input Signal
Grayscale
Input Terminal RF Input
CIRCUIT ADJUST MODE
Activate ........ MENU-0-3-5-7
Function .................AUDIO
Ite m N o . .................VIDEO
Adjus t Data ...........ADJUST
Save Data .... .........ENTER
Exit ..............MENU (twice)
Purpose:
To set the black level of the picture.
Excess or insufficient brightness.
Symptom:
1. Supply a Monoscope signal to a Video Input.
2. Activate the Adjust Mode, VC 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.
40% 30% 20% 10%
50% 0% 0% 0%
60% 70% 80% 90%
GRADATION SCALE
To set overall beam current to its' optimum level.
Purpose
Excess or insufficient contrast.
Symptom:
Note: Activate the Expand mode (full screen).
1. Supply a Grayscale signal to a RF Input.
2. Activate the Adjust Mode, VC 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" to the values given in the Table below.
MODEL
48 inch models
55 inch and 65 inch models
73 inch models
6. Remove the meter.
7. Save data and Exit the Service Mode.
Page 45
CURRENT
525 ±5ua
575 ±5ua
575 ±5ua