Philips L04LAA, Руководство по обслуживанию

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Alignments EN 73 L04L AA 8.
8.
Alignments
Index of this chapter:
1.
General Alignment Conditions
2.
Hardware Alignments
3.
Software Alignments and Settings
Note:
•
The Service Default Mode (SDM) and Service Alignment
Mode (SAM) are described in chapter 5 “Service Modes,
...”.
•
Menu navigation is done with the CURSOR UP, DOWN,
LEFT, or RIGHT keys of the remote control transmitter.
8.1
General Alignment Conditions
Perform all electrical adjustments under the following
conditions:
•
AC voltage and frequency (region dependent):
–
120 V_ac / 60 Hz, or
–
240 V_ac / 50 Hz.
•
Connect the set to the AC power (a.k.a. Mains voltage) via
an isolation transformer with a low internal resistance.
•
Allow the set to warm up for approximately 20 minutes.
•
Measure the voltages and waveforms in relation to chassis
ground (with the exception of the voltages on the primary
side of the power supply). Never use the cooling fins /
plates as ground.
•
Test probe: Ri > 10 Mohm; Ci < 2.5 pF.
•
Use an isolated trimmer / screwdriver to perform the
alignments.
8.2
Hardware Alignments
Figure 8-1 Top view family board
8.2.1
Vg2 Adjustment
1.
Activate the SAM.
2.
Go to the WHITE TONE sub menu.
3.
Set the values of NORMAL RED, GREEN and BLUE to
“32”.
4.
Go, via the MENU key, to the normal user menu and set
5.
SATURATION/COLOR to “0”.
6.
CONTRAST to “0”.
7.
BRIGHTNESS to minimum (OSD just visible).
8.
Return to the SAM via the MENU key.
9.
Connect the RF output of a pattern generator to the
antenna input. Test pattern is a 'black' picture (blank
screen on CRT without any OSD info) with a signal
strength of 1 V_pp.
10.
Set the channel of the oscilloscope to 50 V/div and the time
base to 0.2 ms (external triggering on the vertical pulse).
Ground the scope at the CRT panel and connect a 10:1
probe to one of the cathodes of the picture tube socket (see
diagram B).
11.
Measure the cut off pulse during first full line after the frame
blanking (see figure “V_cutoff waveform”). You will see two
pulses, one being the “cut off” pulse and the other being the
“white drive” pulse. Choose the one with the lowest value;
this is the “cut off” pulse.
12.
Select the cathode with the highest V_dc value for the
alignment. Adjust the V_cutoff of this gun with the
SCREEN potentiometer (see figure “Top view family
board”) on the LOT to 160 V_dc, except for the 25/28BLD
picture tube (Black Line Display, for EU only); this tube
must be aligned to 140 V_dc.
13.
Restore BRIGHTNESS and CONTRAST to normal (= 31).
Figure 8-2 V_cutoff waveform
8.2.2
Focusing
1.
Tune the set to a circle or crosshatch test pattern (use an
external video pattern generator).
2.
Choose picture mode NATURAL with the SMART
PICTURE button on the remote control transmitter.
3.
Adjust the FOCUS potentiometer (see figure “Top view
family board”) until the vertical lines at 2/3 from east and
west, at the height of the centerline, are of minimum width
without visible haze.
1504
C
E_14480_030.eps
130204
A
D
B
LOT
Focus
Screen
VG2
5512
1005
ComPair
1000 (TUNER)
9275
SDM
7990
7601
1506
9252
1221
1204
0V Ref.
E_06532_011.eps
110204
V
CUTOFF
[V
DC
]
max.