LG 21FB3AB-T3, Service Manual

1. Scope of Application

These instructions are applied to CW81A Chassis.

2. Notes

1) Because this is a cold chassis, it is not necessary to use an

isolation transformer. However, operating it using a
transformer between the power supply line and chassis input
to prevent electric shock and to protect the test instrument.

2) All adjustment must be done in the correct sequence.

However, for better productivity, it can be change in a pre-
permitted range.

3) Environment conditions : If not specified, it must be done in

following conditions.
Temperature : 25 ± 5°C
Humidity: 60% ± 10%

4)  Power supply of SET for PAL/SECAM   

China/indonesia/Vietnam/CIS Market: AC100~240V±10%,

50/60Hz.

5) If not specified, the receiver must be operated for more than

20 minutes prior to the adjustment.

6) Signal : Received the standard color signal (65dB±1dBuV).

PAL/SECAM:  LG standard signal means the digital pattern
PAL-B/G 05CH. 

7) If not specified, APC ON is APC CLEAR (DYNAMIC)

3. AGC Voltage Adjustment

3-1. Necessary Instrument

- Digital Multi-meter: 1 set
- Max Input Current : Over 1A/ Max Input Voltage : 500Vdc
- Measurement Range : 10mV-100mVdc/ Accuracy : 0.03%

3-2. Adjustment Preparation

1) Input in the 75

Ω

cable 65dB(±1dB) LG standard signal.

2) Connect the  multi-meter to J105 (AGC Check, Marking).

3-3. Adjustment

1) Press the “INSTART” key of factory remote control and

select “VP0 (RF AGC)” adjustment mode.

2) Press the VOL+/- (

F

/ 

G

) key until the multi-meter shows

reading as shown below.

3) CAUTION: Since the signal strength can be easily

changed by the condition of signal cable, you need to
check the signal strength frequently in order to prevent
error.

4. Screen Voltage Adjustment

4-1. Adjustment 

(Using Factory Remote Control)

1) Input in the 75

Ω

cable LG standard signal (Digital Pattern,

480NC).

2) Press the “ADJ’ key of factory remote control once to make

the TV set display horizontal line.

3) Turn the screen volume on the FBT clockwise until the

horizontal line is visible and turn it counterclockwise until
horizontal line faintly visible.
(Exit screen voltage adjustment by press “Enter(

A

)” key of

factory remote control.)

5. Purity and Convergence Adjustment

5-1. Purity adjustment

(1) Adjustment Preparation

1) Receive Red Raster Pattern for purity adjustment (51CH).
2) Demagnetize the CPT and Cabinet with a degaussing coil.

(2) Adjustment

1) Pre-adjust the static convergence (STC) with the 4 and

6pole magnet.

2) If the horizontal Line is inline with CPT Mark, 2-Pole

magnet should direct 3-9 o’clock direction.

3) If not, direct 2-pole magnet handle toward 6-12 o’clock

direction and adjust the Horizontal Line to fall onto the
mark opening the magnet at an angle.

4) Push the DY(deflection yoke) all the way to the CPT

funnel.

5) Turn the purity magnet(2-pole magnet) so that the “green”

color portion of left side and the “blue” color portion on the
right side have equal amount of color.

6) Pull the DY slowly backward and fix it when the whole

screen becomes red.
(The specified torque for fixing DY screw should be
10Kg/cm.)

5-2. Convergency Adjustment

(1) Necessary Instrument

1) Degaussing Coil
2) Convergency fixing instrument (Speical tools)

(2) Adjustment Preparation

1)  Operate the unit at least 15 minutes before adjustment.
2) Using degaussing coil, remove the stains on CPT &

Cabinet.

3) Received the Cross Hatch Pattern of Convergence. (09ch)
4) Let the Contrast in normal luminance level

.

(3) Static Convergence (STC) Adjustment

1) Receive the Cross Hatch Pattern Convergence (09ch).

G     R     B

- 6 -

ADJUSTMENT

G     R     B

R

G     R     B

6700NFNS11E

6700VS0002F

6700PF0006B

6870NB0026A

6700MF0014A

6700MF0014B

6700MF0018B

6700MF0018A

LGIT

LGIT

SANYO

LGIT

LGIT

LGIT

LGIT

LGIT

2.15 ± 0.05V

3.0 ± 0.05V

2.3 ± 0.05V

2.15 ± 0.05V

2.3 ± 0.05V

2.15 ± 0.05V

2.4 ± 0.05V

2.5 ± 0.05V

65dBu

70dBu

65dBu

65dBu

65dBu

65dBu

65dBu

65dBu

TAEA-H111F

TAEW-G002D

115-B-A86EL

TAEA-J001F

TAEW-G013D

TAEW-G017D

TAEA-G001D

TAEA-G011D

Korea

PAL

PAL

HITACHI

PAL

SECAM(CIS)

PAL

SECAM(CIS)

Tuner P/N

Maker

AGC Vol

Signal

Tuner Spec.

Remark

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Only for training and service purposes.

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