Hitachi 50VF820 - 50" Rear Projection TV, Service Manual

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2-8 GAMMA Correction (White Balance)
GAMMA data (white balance) should not be adjusted. This data are adjusted by the factory
and MEMORY INITialize cannot erase these data. If and only if the customer request to
change the GAMMA correction, follow the instruction below.
(1) Heat run for 10 minutes or more after power on.
(2) The white signal is generated from the internal IC.
(3) Change only the step that are requested to change.
For customer request, it is possible to adjust RGB signal amplitude (means adjust the
gamma correction curve) each signal level (No.1
_
No.32).
If customer require to change the white balance of LCD PTV, we should re-adjust gamma
correction curve.
No.0
_
1 2 3 12 27 28 29 30 31 32
1. ADJUSTMENT PROCEDURE for SERVICE
Input signal level(luminance level) is divided into 32(No.0
_ No.32).
FOR EXAMPLE,
If customer require to change the white balance of 12
th
level of white to reddish, increase
the red value and adjust the white balance of 12
th
signal level (see below).
I 2C MENU
LCDADJ>GAMMA>No.12
(Adjustment)
S TORE THE DATA TO TV SET
LCD ADJ>G/C WRITE
_
press for several second
After this procedure, this new data will be write back to E2PROM. It takes about 20
seconds (picture will be black out).
INPUT SIGNAL LEVEL (A/32step)
For GAMMA CORRECTION
RED GAMMA CORRECTION CURVE
GREEN GAMMA CORRECTION CURVE
BLUE GAMMA CORRECTION CURVE
LCD ADJUST
GAM No.12
R
126->increase this data
G 138
B 105
Final ASSEMBLY ADJUSTMENT
Remark: The gamma data for higher intensity should
always be bigger than that of lower intensity. If
not, noise may appear on the screen.
example:
GAM No11 GAM No12 GAM No13
R 120 > 119 < 127 NG
R 120 < 128 > 127 NG
R 120 < 125 < 127 OK
GAM No12 Red Adjustable Range 120~127
LC58/LC58E
BACK TO ADJUSTMENTS
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