PHILIPS 29PT4423/79R
Manual de Servicio

8
8

Electrical adjustments
Notes : Unless stated otherwise, the supply voltage used is : � � � 220v to 240v +/- 10%, 50 - 60 Hz +/- 5%. Voltage and oscillograms are measured in relation to earth. Never use a heatsink as earth.
Electrical adjustments

L7.3A

29

Enter SAM mode by Dealer Service Tool or short-circuit service pins M28 and M29 on PCB and switch power ON. The menu is displayed whenever SAM mode is entered. Enter into TUNER menu, select items IF-PLL for AFT alignment Method Of Alignment � � Set AFW to 80 kHz Adjust IF-PLL until AFA & AFB just switching from "0" to "1". The correct value for IF-PLL is 61.

For the adjustments a colour pattern generator PM5418 has been used. Pattern generator type PM5193 (optional) .

8.1
8.1.1

Settings on the carrier panel
+ 140 V supply voltage for 25" and 29" picture tubes.

Enter into TUNER menu, select items AGC for RF AGC alignment. Method Of Alignment

Connect a multimeter (DC) across C2551. Set brightness at mid position and contrast at maximum. Apply a pattern generator with a colour bar. Adjust potentiometer R3572 to 140 Volts +/- 1 V DC.

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Connect a multimeter (DC) at pin 1 of tuner. Adjust the AGC until the voltage at pin 1 of the tuner is 4Volts +/- 0.4V DC. The correct value for AGC should be 37.

8.1.2

Geometry adjustments (software adjustment)
Set pattern generator (e.g. PM5418) with colour bar pattern and connect to aerial input with RF signal amplitude - 1mv. Enter SAM mode byusing the Dealer Service Tool or shortcircuit service pins M28 and M29 on PCB and switch power "ON". The menu is displayed whenever SAM mode is entered. Enter into GEOMETRY menu. � Vertical Amplitude and position � Select item VSH and set vertical shift to 31 (Nominal value !!). � Select item VAM and align the top of the screen with vertical amplitude. � Select item VSL and align the bottom of the screen with vertical slope. Horizontal Amplitude and phase � Select item HSH and align horizontal shift until picture to center of the screen. � Select item EW and align the picture width (only those sets with East-West drive circuit). � Select item PW and align East-West parabola for straight vertical lines. � Select item TC and align east-west trapezium for a rectangle. � Repeat if necessary. The value can be increment or decrement by pressing the user remote control right or left key.

8.1.5

Picture demodulator adjustment
Connect a pattern generator (e.g. PM5418) with a cross hatch. Connect an oscilloscope (1ms/div) to pin 6 of IC 7225-5A and adjust L5260 so that the overshoot response is minimum . Select a colour bar signal and verify if the picture is OK.

8.1.6

34.4MHz Trap Alignment
NOTE: For Pal multi set only. GENERAL SET-UP Connect Frequency Synthesizer PM5193 with sine wave and signal strength of 100mv rms. (100dBuv) via a 50 ohm cable terminated with a RC network(50ohm,10nF) and connect to tuner C-CUT (C-CUT OPEN) . Output detection points at saw filter coil 5040 ,pin 3of 1050. The capacitor is in series with the signal, the resitor is vonnected to ground. Adjust L5040 for minimum amplitude.

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8.2
8.2.1

VG2 and White-D settings
Vg2 cut off alignment
Connect a pattern generator (e.g. PM5418) with a black picture , set picture controls of the TV set as following : Brightness: 25 Colour : 30 Contrast: 50 Switch on the TV set and measure with a 100 : 1 scope probe at the cathodes of the picture tube socket pin 6,8 and 11 of CRT sockets C83/84 ; alternately pin 6 for Green, pin 8 for Red and pin 11 for Blue . Measure the level of the pluses and adjust the level of the highest pluses by means of the Vg2 potentiometer (lower knob of LOT 5445). The DC level must be 140 Volts +/- 2V DC for 25" tubes and 160Volts +/-2V DC for 29" picture tubes.

General : The value can be increment or decrement by pressing the user remote control right or left key. The results of the picture will change according to the selected item.

8.1.3

Focusing
Set pattern generator (e.g. PM5418) with colour bar pattern and connect to aerial input with RF signal amplitude of 1mv. Set brightness and contrast at maximum. Adjusted with focusing potentiometer (upper hole of LOT 5445 ) for maximum sharpness of the picture.

8.1.4

IF-PLL / RF AGC adjustment (software adjustment)
Set generator (e.g. PM5418) with colour bar pattern and set frequency for PAL to 189.25MHz and for NTSC 55.25MHz with RF signal amplitudeof 3mv (70dBuv) and connect this signal to the aerial input.