Hitachi CMP5000WXJ Service Manual page 88

6.3.2 Main Unit Adjustment
VOFS/VH/IC5V Voltage Adjustment
Adjusting Point
Input Signal
VR2701 (VOFS)
(Y DRIVE Assy)
White 100%
VR2703 (VH)
(Y DRIVE Assy)
VR2702 (IC5V)
(Y DRIVE Assy)
Note : Be sure to measure between specified test points.
104
VOFS (Offset voltage) adjustment
Method 1
1. Write down a adjustment value of V-OFFSET of REF-DIG mode in the factory mode.
2. Set this adjustment value to center (128).
3. Adjust VR2701 so that the voltage between K2701 (VOFS) and K2703 (SUS GND) becomes
45V.
4. Return it to the value that wrote down a adjustment value of V-OFFSET in step 1.
Method 2
1. Read the adjustment value of V-OFFSET of REF-DIG mode in the factory mode.
2. Adjust VR2701 so that the voltage between K2710 (VOFS) and K2703 (SUS GND) becomes
following voltage ± 0.5V.
Input
DAC Setting
Command Output Voltage
VOF000 0.4
VOF006 0.4984375 25.9375
VOF013 0.61328125 27.03125
VOF019 0.71171875 27.96875
VOF026 0.8265625 29.0625
VOF032 0.925
VOF038 1.0234375 30.9375
VOF045 1.13828125 32.03125
VOF051 1.23671875 32.96875
VOF058 1.3515625 34.0625
VOF064 1.45
VOF070 1.5484375 35.9375
VOF077 1.66328125 37.03125
VOF083 1.76171875 37.96875
VOF090 1.8765625 39.0625
VOF096 1.975
VOF102 2.0734375 40.9375
VOF109 2.18828125 42.03125
VOF115 2.28671875 42.96875
VOF122 2.4015625 44.0625
VOF128 2.5
The symptom is case of mis-adjustment
If the VOFS Voltage adjustment is not performed properly, dots like blinking luminance points
appear. If deviated greatly from the right adjustment point, panel will light white.
VH (voltage for scan IC) Adjustment
Adjust so that the voltage between K2716 (VH) and K2720 (PSUS) becomes 130V ± 0.5V.
PSUS (=GNDH) is a floating GND and the electric potential is different from that of chassis
GND. Be sure not to short-circuit PSUS (=GNDH) and another GND, because that may
damage the unit.
The symptom is case of mis-adjustment
If the VH adjustment is not performed properly, dots like blinking luminance points appear. If
deviated greatly from the right adjustment point, panel will light white.
IC5V Adjustment
Adjust so that the voltage between K2707 (IC5V) and K2720 (PSUS) becomes 5.0V ± 0.1V.
PSUS (=GNDH) is a floating GND and the electric potential is different from that of chassis
GND. Be sure not to short-circuit PSUS (=GNDH) and another GND, because that may
damage the unit.
Adjusting Method
Input
DAC
Command Output
25 VOF134 2.599212598
VOF141 2.71496063
VOF147 2.814173228
VOF153 2.913385827
VOF160 3.029133858
30 VOF166 3.128346457
VOF172 3.227559055
VOF179 3.343307087
VOF185 3.442519685
VOF191 3.541732283
35 VOF198 3.657480315
VOF204 3.756692913
VOF211 3.872440945
VOF217 3.971653543
VOF223 4.070866142
40 VOF230 4.186614173
VOF236 4.285826772
VOF242 4.38503937
VOF249 4.500787402
VOF255 4.6
45
Setting
Voltage
45.94488
47.04724
47.99213
48.93701
50.03937
50.98425
51.92913
53.0315
53.97638
54.92126
56.02362
56.9685
58.07087
59.01575
59.96063
61.06299
62.00787
62.95276
64.05512
65