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Philips Consumer Electronics

Manual 7602
Model no.: 20LW202222
First Publish: 5-10-2001
Rev. Date: 10-16-2002
Print Date: 19/11/2005

Technical Service Data
Service and Quality
Service Publications Dept.
One Philips Drive
P.O. Box 14810
Knoxville, TN 37914

Electrical Adjustments

REFER TO SAFETY GUIDELINES
SAFETY NOTICE: ANY PERSON ATTEMPTING TO SERVICE THIS CHASSIS MUSTFAMILIARIZE
HIMSELF WITH THE CHASSIS AND BE AWARE OF THE NECESSARY SAFETY PRECAUTIONS
TO BE USED WHEN SERVICING ELECTRONIC EQUIPMENT CONTAINING HIGH VOLTAGES.
CAUTION: USE A SEPARATE ISOLATION TRANSFORMER FOR THIS UNIT WHEN SERVICING
© Philips Electronics North America Corporation

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Alignments
Note: The Service Default Mode (SDM) andService Alignment Mode (SAM) are described in Service Modes Error
Codes And Fault Finding. Menu navigation is done with the 'CURSOR UP, DOWN, LEFT or RIGHT' keys of the
remote control transmitter.

General Alignment Conditions
Perform all electrical adjustments under the following conditions:
•
•
•
•

AC voltage and frequency: 110 V (± 10 %), 60 Hz (± 5 %).
Connect the set to the ACpower via an isolation transformer.
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 MΩ; Ci < 2.5 pF.
Use an isolated trimmer / screwdriver to perform the alignments.Hardware Alignments

Fig. 1

Vg2 Adjustment
1.
2.
3.
4.

Activate the SAM.
Go to the WHITE TONE sub menu.
Set the values of NORMAL RED, GREEN and BLUE to 40.
Go, via the MENU key, to the normal user menu and set
- CONTRAST to zero.
- BRIGHTNESS to minimum (OSD just visible in a dark room).
5. Return to the SAM via the MENU key.
6. Connect the RF output of a pattern generator tothe antenna input. Test pattern is a 'black' picture (blank screen
on CRT without any OSD info).

7. Set the channel of the oscilloscope to 50 V/div and the time base to 0.2 ms (external triggering on the vertical
pulse).
8. 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).
9. Measure the cut off pulse during firstfull line after the frame blanking (see Fig. 2). 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.
10. Select the cathode with the highest VDC value for the alignment. Adjust the Vcutoff of this gun with the SCREEN
potentiometer (see Fig. 1) on the LOT to the correct value (see tablebelow).
11. Restore BRIGHTNESS and CONTRAST to normal (= 31).

Fig. 2

Focusing
1. Tune the set to a circle or crosshatch test pattern (use an external video pattern generator).
2. Choose picture mode NATURAL (or MOVIES) with the 'SMART PICTURE' button on the remote control
transmitter.
3. Adjust the FOCUS potentiometer (see Fig.1) until the vertical lines at 2/3 from east and west, atthe height of the
centerline, are of minimum width without visible haze.

Software Alignments And Settings
Enter the Service Alignment Mode (see Service Modes Error Codes And Fault Finding.). The SAM menu will now
appear on the screen.

Options

Display Option Byte Table

Options are used to control the presence / absence of certain
features and hardware.

How to change an Option ByteAn Option Byte represents a number of different options.
Changing these bytes directly makes it possible to set all options very fast. All options are controlled via seven option
bytes. Select the option byte (OB1.. OB7) with the MENU UP/DOWN keys, and enter the new value.
Leaving the OPTION submenu saves changes in the Option Byte settings. Some changes will only take effect after
the set...