LG CN14D99 Service Manual

ADJUSTMENT INSTRUCTION

These instructions are applied to only NC-6HA chassis.

Notes

1.Because this is not a hot chassis, it is not necessary to use an isolation transformer. However, the use of isolation transformer will help protect test instrument.

2.Adjustment must be done in the correct order.

3.Supply

4.The receiver must be operated for about 30 minutes proir to

100~240V A.C./50~60Hz.

the adjustment.

CONTENTS

1. VCO/AFT Adjustment

2. SIF Adjustment

3. Stereo separation Adjustment

4. AGC voltage Adjustment

5. Screen voltage Adjustment

6. White Balance Adjustment

7. FOCUS Adjustment

8. Sub-Bright Adjustment

1. VCO/AFT Adjustment

1) Connect the DMM to pin 13 of IC501.

2) Disconnect the antenna cable.

3) Press SET-UP buttons on the Remote control and the front

panel of TV set at the same time to get into the adjustment mode.

Press channel Up/Down buttons to select an adjustment. Press volume Up/Down buttons to vary the data.

4) Select APCADJ mode by pressing channel Up/Down

button.

5) Adjust APCADJ data by pressing volume Up/Down button

untill the DMM

6) Input the Digital pattern signal.

7) Select VCORUN mode by pressing channel Up/Down

button.

8) Adjust VCORUN data by pressing volume Up/Down button

untill the DMM re

reads 3.8+_ V.

ads 3.8+_0.2V.

0.3

0.2

2. SIF Adjustment

1) Input 100% modulated 1KHz sound signal.

2) Connect DMM to pin 7 of IC501.

3) Adjust L104 untill DMM reads 3.8+_0.2V.

3. Stereo separation Adjustment

3-1. Preparation

1) Connect the measuring equipment to the TV as show in Fig. 1.

2) Press SET-UP buttons on the Remote control and the front

panel of TV set at the same time to get into the adjustment mode.

3-3. Stereo VCO(ST) Adjustment

1) Disconnect the Modulator and connect C1 and the frequency counter.

2) Select ST VCO with CHANNEL button and adjust with VOLUME button until the frequency of JP at R617 is

15.734

+_0.1KHz.

OSCILLOSCOPE

IC601

C607

TV SOUND MULTIPLEX MODULATOR(USA)

FREQUENCY COUNTER

R617

C619

3-4. Filter Adjustment

Select FILTER with CHANNEL button and adjust with VOLUME button until the waveform becomes minimum.

3-5. Separation Adjustment

1) Select ST L-only 300Hz signal 30% Modulation of Modulator.

2) Select LSPRT with CHANNEL button and adjust with VOLUME button until the waveform is minimum.

3) Change the frequency of Modulator to 3KHz.

4) Select HSPRT with CHANNEL button and adjust with VOLUME button until the waveform is minimum.

5) Select LSPRT and reduce 10 steps.

3-6. SAP VCO Adjustment

1) Disconnect the Modulator and connect C1 and the frequency counter.

2) Select SAP VCO and adjust until the frequency becomes

78.67

+_0.5KHz

4. AGC voltage Adjustment

4-1. Preparation

Connect the DMM to J64 on Main PCB.

4-2. Adjustment

1) Select AGCDLY with CHANNEL button in Adjustment mode.

2) Adjust with VOLUME button until the voltage is 5.6+_0.1V.

3-2. ATT input level adjustment

Select ATT with CHANNEL button and adjust with VOLUME

button until the voltage of JP at R620

is 1.414+_0.03Vp-p.

5. Screen Voltage Adjustment

5-1. Make the screen has the horizontal line by Remote control. 5-2. Turn the screen control clockwise until the Horizontal line is

visible and turn it counterclockwise until the Horizontal line is faintly visible.

- 1-

6. White Balance Adjustment

6-1. Preparation

1) Press the APC button on the Remote control for APC ON condition. APC ON CONTRAST : 100

BRIGHT : 50 COLOR : 50 TINT : 0 SHARPNESS : 60

2) Set the screen for Adjustment mode by Remote Control.

6-2. Adjustment

1) Adjust the CONTRAST and BRIGHT for 40FT-1.

2) Select G-DRIVER for data Y and B-DRIVER for data X and

adjust for High Light condition. X=282, Y=288(10000+_800

3) Adjust the CONTRAST and BRIGHT for 4.5FT-1.

4) Select G-BIAS for data Y and B-BIAS for data X and adjust for

Low Light condition. X=282, Y=288(10000+_800)

5) Repeat above 1) ~ 4) for good white balance.

7. FOCUS Adjustment

1) Press the APC button on the Remote Control for APC ON condition.

2) Adjust the FOCUS control on the FBT to obtain a sharp and clear picture.

8. Sub-Bright Adjustment

1) Input the Mono scope signal as Fig. 2.

2) Set the screen for Adjustment Mode by Remote Control.

3) Select Sub-Bright and adjust until A part is distinguishable.

10 23456789

- 2-

PURITY & CONVERGENCE ADJUSTMENT

Caution:

Convergence and Purity have been factory aligned. Do not attempt to tamper with these alignments. However, the effects of adjacent receiver components, or replacement of picture tube or deflection yoke may require the need to readjust purity any convergence.

DEFLECTION YOKE

PURITY &CONVERGENCE MAGNET ASSEMBLY

6-POLE

,,,

RUBBER WEDGES

,,,

PURITY MAGNET

4-POLE

GLASS CLOTH TAPE

X-AXIS YOKE POSITIONING (L/R PURITY)

5.Reconnect the internal degaussing coil.

6. Position the beam bender locking rings at the 9 o'clock position and the other three pairs of tabs (2,4 and 6 pole magnets) at the 12 o'clock position.

6-POLE

MAGNETS

4-POLE MAGNET

MAGNES

CONVERGENCE MAGNET ASSEMBLY

PURITY MAGNET(2-POLE)

* Purity Adjustment

This procedure DOES NOT apply to bonded yoke and picture tube assemblies. The instrument should be at room temperature (60 degrees F or above) for six (6) hours and be operating at low beam current (dark background) for approximately 20 to 30 minutes before performing purity adjustments.

CAUTION:Do not remove any trim magnets that may be

attached to the bell of the picture tube.

1. Remove the AC power and disconnect the internal degaussing coil.

2. Remove the yoke from the neck of the picture tube.

3. If the yoke has the tape version beam bender, remove it and replace it with a adjustable type beam bender (follow the instructions provided with the new beam bender)

4. Replace the yoke on the picture tube neck, temporarily remove the three (3) rubber wedges from the bell of the picture tube and then slide the yoke completely forward.

7. Perform the following steps, in the order given, to prepare the receiver for the purity adjustment procedure.

a. Face the receiver in the "magnetic north" direction.

b. Externally degauss the receiver screen with the television

power turned off.

c. Turn the television on for approximately 10 seconds to

perform internal degaussing and then turn the TV off.

d. Unplug the internal degaussing coil. This allows the

thermistor to cool down while you are performing the purity adjustment. DO NOT MOVE THE RECEIVER FROM ITS "MAGNETIC NORTH" POSITION.

e. Turn the receiver on and obtain a red raster by increasing

the red bias control (CW) and decreasing the bias controls for the remaining two colors (CCW).

f. Attach two round magnets on the picture tube screen at 3

o'clock and 9 o'clock positions, approximately one (1) inch from the edge of the mask (use double-sided tape).

3-2

1.ADJUST YOKE Z-AXIS FIRST TO GET EQUAL BLUE COLOR CIRCLES

MAGNETS

RED RED

2 .ADJUST BEAM BENDER 2 POLE MAGNET TO GET FOUR EQUAL COLOR CIRCLES

8. Referring to above, perform the following two steps: a. Adjust the yoke Z-axis to obtain equal blue circles. b. Adjust the appropriate beam bender tabs to obtain correct

purity (four equal circles).

9. After correct purity is set, tighten the yoke clamp screw and

remove the two screen magnets.

10.Remove the AC power and rotate the receiver 180 degrees

(facing "magnetic south").

11. Reconnect the internal degaussing coil.

12. Turn the receiver on for 10 seconds (make sure the receiver

came on) to perform internal degaussing, and then turn the receiver off.

13. Unplug the internal degaussing coil.

14. Turn on the receiver and check the purity by holding one (1)

round magnet at the 3 o'clock and a second round magnet at 9 o'clock position. If purity is not satisfactory, repeat steps 8 through 14.

15. Turn off the receiver and reconnect the internal degaussing

coil.

* Convergence Adjustment

Caution:This procedure DOES NOT apply to bonded yoke and

picture tube assemblies. Do not use screen magnets during this adjustment procedure. Use of screen magnets will cause an incorrect display.

1. Remove AC power and disconnect the internal degaussing

coil.

2. Apply AC Power and set the brightness to the Picture Reset

condition. Set the Color control to minimum.

3. Apply 8V to the pin.

6. Reconnect the internal degaussing coil and apply AC power.

7. Turn the receiver on for 10 seconds to perform internal degaussing and then turn the receiver off again.

8. Unplug the internal degaussing-coil.

9. Turn on the receiver, connect a signal generator to the VHF antenna terminal and apply a crosshatch signal.

Caution:During the convergence adjustment procedure, be

very careful not to disturb the purity adjustment tabs are accidentally move, purity should be confirmed before proceeding with the convergence adjustments.

Note:

Make sure the focus is set correctly on this instrument

before proceeding with the following adjustment.

10. Converge the red and blue vertical lines to the green vertical line at the center of the screen by performing the following steps (below TABLE). a. Carefully rotate both tabs of the 4-pole ring magnet

simultaneously in opposite directions from the 12 o'clock position to converge the red and blue vertical lines.

b. Carefully rotate both tabs of the 6-pole ring magnet

simultaneously in opposite directions form the 12 o'clock position to converge the red and blue (now purple) vertical lines with the green vertical line.

11. Converge the red and blue horizontal with the green line at the center of the screen by performing the following steps. (below TABLE)

a. Carefully rotate both tabs of the 4-pole ring magnet

simultaneously in the same direction (keep the spacing between the two tabs the same) to converge the red and blue horizontal lines.

b. Carefully rotate both tabs of the 6-pole ring magnet

simultaneously in same direction (keep the spacing between the two tabs the same) to converge the red and blue (now purple) horizontal lines with the green horizontal line.

c. Secure the tabs previsouly adjusted by locking them in

place with the locking tabs on the beam bender.

4. Adjust the Red, Green and Blue Bias controls to get a dim white line.

5. Remove the AC power and 8V from the pin.

3-3

3-4

RING PAIRS

POLE

ROTATION DIRECTION

OF BOTH TABS

OPPOSITE

SAME

OPPOSITE

SAME

MOVEMENT OF RED

AND BLUE BEAMS

B B

B R B R

B R

POLE

12. While watching the 6 o'clock positions on the screen, rock the front of the yoke in a vertical (up/down) direction to converge the red and blue vertical lines. (Fig upper left)

13. Temporarily place a rubber wedge at the 12 o'clock position to hold the vertical position or the yoke.

14.

Check the 3 o'clock and 9 o'clock areas to confirm that the red and blue horizontal lines are converged. If the lines are not converged, slightly offset the vertical tilt of the yoke (move the rubber wedge if necessary) to equally balance the convergence error of the horizontal lines at 3 o'clock and 9 o'clock and the vertical lines at 6 o'clock and 12 o'clock.

15. Place a 1.5 inch piece of glass tape over the rubber foot at the rear of the 12 o'clock wedge.

16. While watching the 6 o'clock and 12 o'clock areas of the screen, rock the front of the yoke in the horizontal (left to right) motion to converge the red and blue horizontal lines. (Fig. upper right)

17. Temporarily place a rubber wedge at the 5 o'clock and 7 o'clock positions to hold the horizontal position of the yoke.

18. Check the 3 o'clock and 9 o'clock areas to confirm that the red and blue vertical lines are converged. If the lines are not converged, slightly offset the horizontal tilt of the yoke (move the temporary rubber wedges if necessary) to equally balance the convergence error of the horizontal lines at 6 o'clock and 12 o'clock and the vertical lines at 3 o'clock and 9 o'clock.

19. Using a round magnet confirm purity at the center, right and left sides and corners. See Purity Adjustment Procedure.

20. Reconfirm convergence and apply a 1.5 inch piece of glass tape over the rubber foot at the rear of the 5 o'clock and the 7 o'clock wedges.

RED BLUE

BLUE

RED

GREEN

BLUE RED

GREEN

ADJUSTMENT

VIEWING

AREA

UP/DOWN ROCKING OF THE YOKE CAUSES OPPOSITE ROTATION OF RED AND BLUE RASTERS

ADJUSTMENT

VIEWING

AREA

RED

GREEN

TV SCREEN

LEET/RIGHT ROCKING OF THE YOKE CAUSES OPPOSITE SIZE CHANGE OF THE RED AND BLUE RASTERS

UP/DOWN ROCKING OF THE YOKE CAUSES OPPOSITE ROTATION OF RED AND BLUE RASTERS

LEFT/RIGHT ROCKING OF THE YOKE CAUSES OPPOSITE SIZE CHANGE OF THE RED AND BLUE RASTERS

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