LG cf-21d33e ADJUSTMENT INSTRUCTIONS

ADJUSTMENT INSTRUCTIONS

:Safety precautions

1. It is safe to adjust after using insulating transformer between the power supply line and chassis input to prevent the risk of electric shock and protect the instrument.

2.Never disconnect leads while the TV receiver is on.

3. Don't short any portion of circuits while power is on.

4. The adjustment must be done by the correct appliances. But this is changeable in view of productivity.

5. Unless otherwise noted, set the line voltage to 220Va c!20%, 50/60Hz.

:Test Equipment required

1. Swee p Generator

2. Marker Generator(38.0MHz: Picture/32.5MHz: Sound)

3. Alignmen t Scope(5121A)

4. Patter n Generator(PAL/SECAM)

5. DC Power Supply

6.Color analyzer

7.Multimeter(Volt meter)

Preparation for VCO Adjustment

1. Connect the measuring equipment to the TV as shown in Fig. 1

2. Set RF output level of Sweep Generator to 90dBuV.

:VCO (Voltage Controlled Oscillator)

Adjustment

Test Point : JP4(L504)

Adjust : VL501

1) Turn on DC power supplies.

2) Adjust VCO ADJ. coi l (VL501)so that the level of Picture

Carrier (PC) may be at the lowest position as shown Fig.

SC (Sound Carrier) : 32.5 MHz

PC (Picture Carrier) : 38.0 MHz

Fig. 2: Output waveform on Alignment Scope

NOTE: When performing this adjustment, if there are 2

adjusted point in VL501, select the lower core position.

MAIN BOARD

C533 (JP 3)

J9 AGC ADJ.

CK

0.01uF

RF out

SWEEP S.G with Marker

TUNER

Z101 (JP 1)

Hor

Ver

VL501 VCO ADJ.



Alignment Scope

L504

(JP 4)

IC501

3.3K

DC POWER SUPPLY



5.0 +0.1V

Fig. 1: Connection Diagram of Equipment for VCO Adjustment

IC401

(JP 6)

DC POWER SUPPLY



16 +0.5V

RF AGC (Auto Gain Control) Adjustment

Test Point :

J9(AGC ADJ.) or Observing Display

Adjust : VR501

The RF AGC contro l VR501 was aligned at the time of manufacture for optimum performance over a wide range conditions. Readjust o f VR501should not be necessary unless unusual local conditions exist, such as;

1)Channel interference in a CATV system

2)Picture bending and/or color beats, which are unusually due to excessive RF signal input when the reciever is too close to a transmitting tower or when the receiver is connected to an antenna distribution system where the RF signal has been amplified. In this case, the input signal should be attenuated(with pad or filter) to a satisfactory level. Picture noise caused by "broadcast noise" or weak

3) signal. If the broadcast is "clean" and the RF signal is at least 1mV (60dBu), the picture will be noise free in any area.

- 1-

Adjusting the VR501(RF AGC) control to one end of rotation will usually cause a relatively poor signal to noise ratio; Adjusting to the other end of rotation will usually cause a degradation of over load capabilities resulting on color beats or adjacent channel interference. For the best results, adjust VR501 contol while performing on all other local channels, or Refer to the

following Table 1.

: Vertical Height, Center Adjustment

1) Tune the TV set to receive a digital test pattern.

2) Set standard picture mode(contrast: 80, bright :60, color: 50).

3) Adjust the Verical height control (VR301) so that the circle of a digital test pattern may be located within the effective screen of the CPT.

4) Adjust the Vertical center control (VR302) for obtaining geometric center of valuable display vertically.

: Focus Adjustment

NOTE: This adjustment should be performed after

warming up for 10 minutes.

1) Tune the TV set to receive a digital test pattern.

2) Adjust the Focus control for the best overall focus.

: Horizontal Center Adjustment

1) Tune the TV set to receive a PAL digital pattern.

2) Adjust the Horizontal center control (VR502) for obtaining geometric center of valubale display horizontally.

: Screen & White Balance

(color temperature) Adjustment

NOTE:

1) Set all the controls (VR901-VR905) on CPT Board to geometric center position.

Set the standard mode (contrast : 80, bright : 60, color : 50).

3) Set the AV mode, adjust and set the screen volume of FBT at just cut-off position(No AV input signal).

4) Set the TV mode, tune the TV set to receive white pattern.

By using color analyzer (white balance checker), adjust X position equals to 281

8 and Y position equals to

288

8, it means that color temperature is 10000!800¡£K

at low light (4.5ft¡⁄L) and high light (over 45ft¡⁄L).

- 2 -

Tuner P/N 113-118B/F/J 113-238H 6700VMV001A

Maker LG-ALPS LG-ALPS SANYO

REMARK RF 60!1dBuV RF 60!1dBuV RF 60!1dBuV

Adjustment Voltage

5.7!0.1Vdc

6.0!0.1Vdc

4.9!0.1Vdc

Test Point : Observing display

Adjust : VR301 (Vertical Height)

VR302 (Vertical Center)

Test Point : Observing display

Adjust : Focus control of FBT

Test Point : Observing display

Adjust : VR502

1. This adjustment should be performed after warming up for 20 minutes.

2. The color bias controls (VR901, VR902, VR903) affect the low light (dark) area of the picture while the color drive controls (VR904, VR905) affect the high light (white) areas.