LG MC-7CD Service Manual

VIDEO AUDIO

CHROMA

- 1 -

ADJUSTMENT INSTRUCTION

These instructions are applied to only MC-7CA 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 100~240V A.C./50~60Hz.

4.The receiver must be operated for about 20 minutes proir to the adjustment.

CONTENTS

1. Stereo separation Adjustment

2. VCO Adjustment

3. AGC voltage Adjustment

4. Screen voltage Adjustment

5. White Balance Adjustment

6. FOCUS Adjustment

7. Sub-Bright Adjustment

8. Deflection Setting Data Adjustment

9. H-Size & SIDE PIN CUSHION Adjustment

1. Stereo separation Adjustment

1-1. Preparation

(1) Connect the measuring equipment to the TV as shown in Fig. 1. (2) Open R601 and R602 to disconnect RF Audio signal. (3) Press MENU button on the TV set and MENU button on

the Remote control at the same time to get into Adjustment mode.

1-2. ATT input level adjustment

(1) Input 100Hz, 245mVrms(693mVp-p) signal to pin5 of IC601. (2) Connect the Oscilloscope to pin 7 of IC601. (3) Select ATT with CHANNEL button and adjust with VOLUME

button until the voltage of pin 7 is 1.38Vp-p(490mVrms). (ATT : 0~15)

1-3. Stereo(ST) & SAP VCO Adjustment

(1) Disconnect the Modulator and connect the frequency counter

to pin 9 of IC601.

(2) Select ST VCO with CHANNEL button and adjust with

VOLUME button until the frequency is 62.936

!0.1KHz.

(VCO : 0~63)

1-4. Filter Adjustment

(1) Input 9.4KHz, 600mVrms(1.697Vp-p) signal to pin 5 of IC601. (2) Connect the Oscilloscope to pin 9 of IC601. (3) Select FILTER with CHANNEL button and adjust with

VOLUME button until STATUS becomes the center of 1. (FILTER : 0~63)

1-5. Separation Adjustment

(1) Input ST L-only 300Hz signal 30% Modulation of Modulator to

pin 5 of IC601. (2) Connect the Oscilloscope to pin 9 of IC601. (3) Select WIDEBAND with CHANNEL button and adjust with

VOLUME button until the waveform is minimum.

(WIDEBAND : 0~63) (4) Change the frequency of Modulator to 3KHz. (5) Select SPECTRAL with CHANNEL button and adjust with

VOLUME button until the waveform is minimum.

(SPECTRAL : 0~63)

2. VCO Adjustment

(1) Connect the antenna cable. (2) Press MENU button on the TV set and MENU button on

the Remote control at the same time to get into Adjustment

mode.

Press channel Up/Down buttons to select an adjustment.

Press volume Up/Down buttons to vary the data. (3) Select VP 0(AUTOPIF) mode by pressing channel

Up/Down button.

OSD will be displayed in Orange. (4) Adjust VP 0(AUTOPIF) data by pressing volume Up/Down

button.

OSD(AUTOPIF) color is changed to Green.

3. AGC voltage Adjustment

3-1. Preparation

Connect the DMM to J101 on Main PCB.

3-2. Adjustment

(1) Select VP 1(RFAGC) with CHANNEL button in Adjustment

mode. (2) Adjust with VOLUME button until the voltage is 4.6!0.1V.

4. Screen Voltage Adjustment

(1) Input the Digital Pattern to TV set. (2) Press the APC button on the Remote Control for APC ON.

APC ON CONTRAST : 100

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

(3) Make the screen has the horizontal line by pressing SVC

button of service Remote control. (4) Turn the screen control clockwise until the Horizontal line is

visible and turn it counterclockwise until the Horizontal line

is faintly visible.

MULTIPLEX

MODULATOR

IC601

Vcc GND SCL SDA MPX

GND Lo GND Ro

12 3 4 5 6 7 8 9

+ 4 hidden pages