LG 50GA6400, Service Manual

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Only for training and service purposes
4.4. White Balance Adjustment
4.4.1. Overview
▪ W/B adj. Objective & How-it-works
(1) Objective: To reduce each Panel’s W/B deviation
(2) How-it-works: When R/G/B gain in the OSD is at 192, it
means the panel is at its Full Dynamic Range. In order to
prevent saturation of Full Dynamic range and data, one of
R/G/B is fixed at 192, and the other two is lowered to find
the desired value.
(3) Adj. condition: normal temperature
- Surrounding Temperature: 25±5 °C
- Warm-up time: About 5 Min
- Surrounding Humidity: 20% ~ 80%
4.4.2. Equipment
(1) Color Analyzer: CA-210 (NCG: CH 9 / WCG: CH12 / LED:
CH14)
(2) Adj. Computer (During auto adj., RS-232C protocol is
needed)
(3) Adjust Remocon
(4) Video Signal Generator MSPG-925F 720p/204-Gray
(Model: 217, Pattern: 49)
※
Color Analyzer Matrix should be calibrated using CS-1000
4.4.3. Equipment connection
4.4.4. Adjustment Command (Protocol)
(1) RS-232C Command used during auto-adj.
RS-232C COMMAND
Explanation
CMD DATA ID
Wb 00 00 Begin White Balance adj.
Wb 00 ff End White Balance adj.
(internal pattern disappears )
(2) Adjustment Map
Adj. item Command
(lower caseASCII)
Data Range
(Hex.)
CMD1 CMD2 MIN MAX
Cool R Gain j g 00 C0
G Gain j h 00 C0
B Gain j i 00 C0
Medium R Gain j a 00 C0
G Gain j b 00 C0
B Gain j c 00 C0
Warm R Gain j d 00 C0
G Gain j e 00 C0
B Gain j f 00 C0
4.4.5. Adj. method
4.4.5.1. Auto adj. method
(1) Set TV in ADJ mode using P-ONLY key (or POWER ON
key)
(2) Place optical probe on the center of the display
- It need to check probe condition of zero calibration before
adjustment.
(3) Connect RS-232C Cable
(4) Select mode in ADJ Program and begin a adjustment.
(5) When WB adjustment is completed with OK message,
check adjustment status of pre-set mode (Cool, Medium,
Warm)
(6) Remove probe and RS-232C cable.
▪ W/B Adj. must begin as start command “wb 00 00” , and
finish as end command “wb 00 ff”, and Adj. offset if need
4.4.5.2. Manual adj. method
(1) Set TV in Adj. mode using POWER ON
(2) Zero Calibrate the probe of Color Analyzer, then place it on
the center of LCD module within 10cm of the surface..
(3) Press ADJ key -> EZ adjust using adj. R/C -> 9. White-
Balance then press the cursor to the right (KEY►). When
KEY(►) is pressed 216 Gray internal pattern will be
displayed.
(4) Adjust Cool modes
(i) Fix the one of R/G/B gain to 192 (default data) and
decrease the others. ( If G gain is adjusted over 172 and
R and B gain less than 192 , Adjust is O.K.)
(ii). If G gain is less than 172,
Increase G gain by up to 172, and then increase R gain
and G gain same amount of increasing G gain.
(iii) If R gain or B gain is over 255,
Readjust G gain less than 172, Conform to R gain is 255
or B gain is 255
(5) Adjust two modes (Medium / Warm) Fix the one of R/G/B
gain to 192 (default data) and decrease the others.
(6) Adj. is completed, Exit adjust mode using “EXIT” key on
Remote controller.
▪ If internal pattern is not available, use RF input. In EZ Adj.
menu 6.White Balance, you can select one of 2 Test-pattern:
ON, OFF. Default is inner (ON). By selecting OFF, you can
adjust using RF signal in 206 Gray pattern.
▪ Adj. condition and cautionary items
(1) Lighting condition in surrounding area
Surrounding lighting should be lower 10 lux. Try to isolate
adj. area into dark surrounding.
(2) Probe location: Color Analyzer (CA-210) probe should be
within 10cm and perpendicular of the module surface (80°~
100°)
(3) Aging time
- After Aging Start, Keep the Power ON status during 5
Minutes.
- In case of LCD, Back-light on should be checked using no
signal or Full-white pattern.