Philips 202P70/00 Service Manual page 6

6 202P7 CRT
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One test circuit should be added to up high the EHT voltage
during the adjustment:
Adjust 1Mohm pot-meter (decrease the resistance from Max
position) gradually to Increase the EHT voltage to 29.0 KV
and then slowly decrease the X-ray protection activation
voltage by adjusting R3695 until the X-ray protection circuit is
just activated.
Turn off the set and adjust 1Mohm pot-meter to maximum value
and then re-start the power again.Re-test the X-ray protection
by slowly increasing the EHT voltage (rotate 1Mohm pot-meter
to smaller value) to confirm the X-ray protection activation voltage
to be 29.0 KV ± 0.5KV, fix the R3695VR with silicon glue after
passing re-test.
7. Alignment of VG2 cut-off, white tracking, auto
calibration & Smart Mode
7.1 External degaussing
7.1.1 Remove ferromagnetic measuring equipment, Iron tablet etc
in the neighbourhood of the apparatus within the half meter.
7.1.2 Positioned in the E - W direction (CRT face east), the monitor
has to be degaussed by using external degaussing coil.
Remark: The external degaussing coil should be a stick type,
can' t use ring type for SDI DFT CRT, and set the
electrical current of purity coils (N/S) equal to zero,
which means the output of PWM 4 of 7204 (61P4K
420WT) equal to 128, or switch off the monitor before
external degaussing.
7.1.3 Slowly increase the distance between the picture tube and
degaussing coil, keep the coil in parallel with the screen of CRT
when the distance is more than 2 M, then turn off the
degaussing current.
7.1.4 Pre-check the purity by using "full RED pattern" after external
degaussing, the user (OSD) control -"adjust purity" can be
used to optimize the purity performance in pure RED, this
action can help to achieve a correct white tracking adjustment.
7.1.5 Switch on the AUTO CALIBRATE function to "AUTO" in the
EXTRA CONTROL item of OSD MAIN CONTROLS TABLE.
7.2 Apply 69KHz/85Hz with full white & 10cm X 10cm white
patterns (video as 0.7Vpp) *Use color analyzer (Minolta
CA-100) to adjust cutoff and white uniformity.
Preset (OSD control in the factory mode) following items with
initial data (DAC value):
R cut off (BAIS) = 50% , R gain (GAIN) = 75%
G cut off (BAIS) = 50% , G gain (GAIN) = 75%
B cut off (BAIS) = 50% , B gain (GAIN) = 75%
Remark: 100% = 255 steps, 60% = 153 steps, 50% = 128
steps, 75% = 191 steps, 70% = 179 steps.
Electrical Instructions
270K 3697
68K
1M
SW
3698
20K
sub contrast
(SUB)= 70%
ABL = 50%
7.2.1 Moving the OSD cursor to any one of R/G/B (BAIS), CPU
software will set brightness control at 50% and contrast at
minimum position when OSD cursor stays at BAIS items.
Measure the light output at center of the screen.
Rotate Vg2 to Minimum voltage.
Slowly increase Vg2 voltage until light output is at
reading from 0.06 to 0.07Ft-L.
Adjusting the cut off of R & B to get 9300 °K (X= 0.283 ± 0.006,
7.2.2
Y= 0.297 ± 0.006) and brightness output at reading from 0.06
to 0.07 Ft-L (may need to readjust the Vg2).(Apply a signal with
10cm X 10cm white pattern to test set.) * Keep G cut off with
128 (50%) DAC value during all alignments.
Move the cursor to 9300 °K R/G/B (GAIN) items.CPU software
7.2.3
will set contrast to maximum when adjustment OSD cursor
stays at GAIN items.
Adjust the gains of R/B to get 9300 °K (x=0.283, y=0.297).
7.2.4 Move the cursor to sub-contrast and adjust the brightness to
34 ±0.5 Ft-L.
7.2.5 Switch the input signal to full white pattern. Move the OSD
cursor to ABL and adjust the output brightness to 32 ±0.5 Ft-L.
7.2.6 Repeat 7.2.2, 7.2.5 to get optimal adjustment (white tracking
meet requirement ±0.015 with respect to center value) and
return to main menu. After exit, the OSD will disappear and
auto-save the data.
Repeat 7.2.2 to adjust 6500 °K 'cut off' to meet (X= 0.313 ±
7.2.7
0.006, Y= 0.329 ± 0.006).
Repeat 7.2.3 to adjust R/G/B 'GAIN' of 6500 °K to meet (x=
7.2.8
0.313, y= 0.329) and brightness output to 30±1 Ft-L.
Repeat 7.2.2 to adjust 5500 °K 'cut off' to meet (X= 0.332 ±
7.2.9
0.006, Y= 0.347 ± 0.006).
Repeat 7.2.3 to adjust R/G/B 'GAIN' of 5500 °K to meet (x=
7.2.10
0.332, y= 0.347) and brightness output to 27±1 Ft-L.
7.2.11 Repeat 7.2.2 to adjust sRGB 'cut off' to meet (x= 0.313 ±
0.006, y= 0.329 ± 0.006).
7.2.12 Repeat 7.2.3 to adjust R/G/B 'GAIN' of sRGB to meet (x=
313, y=329) and brightness output to 23±1 Ft-L.
7.3 Apply black pattern and check raster for just visible cut-off
at brightness 50%.
7.4 Alignment result will be stored by UUT itself, after finish white
balance adjustment.
7.5 Alignment of Auto calibration
7.5.1 After finish the white balance adjustment, select the 9300K in
OSD ADJUST COLOR,enable & select the AUTO CALIBRATE
in OSD item - EXTRA CONTROL, press the OK key pad to do
the auto calibration measurement, store the beam current values.
7.5.2 Repeat the procedure in 7.5.1 to measure and store the beam
current values in 6500K,5500K and sRGB.
Notes : Beam current measuring and white balance adjustment
can be done by command from CAA alignment Program (
according to software approval Sheet 140,139 ).
7.5.3 Switch on (AUTO) the auto calibration function after finish all
alignment items.
7.6 Smart Mode color adjustment - This process only can be taken
by CAA test program.
CAA takes the 6500 °K 'cut off' and R-gain DAC values as a
7.6.1
reference and keep them fixed to proceed others color
temperatures .