LG NC5AA Diagram

ADJUSTMENT INSTRUCTION

These instructions are applied to only NC-5AA chassis.

Notes

1.So this is a hot chassis, you must be careful, and be caution not to touch 1st and 2nd concurrently.

2.Adjustment must be done in the correct order.

3.Power supply of a SET which is adjusted is 100~240V A.C./50~60Hz.

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

CONTENTS

1) VIF, AFT and SIF Adjustment

2) Sound Multiplex Adjustment

3) FOCUS Adjustment

4) AGC Adjustment

4)-1 Picture AGC Adjustment

5) V-Size and V-Center Adjustment

6) Horizontal Size, Center and Side Pincushion Adjustment

7) Purity and Convergence Adjustment

8) White Balance Adjustment

9) SUB-Bright Adjustment

10) Vertical Center Adjustment

11) Horizontal Center Adjustment

1. VCO and AFT Adjustment

This Adjustment must be applied only to PCB Assy.

1.1. Necessary Instruments

1) Sweamer Generator : can sweep 35MHz~55MHz(over

120dBu)

2) PLUG in Unit : With PIF(45.75MHz), SIF(41.25MHz) Marker

3) Alignment Scope : X-Y mode, 10mV~20V Variable

4) D.C. Power Supply : 0~12V Variable

5) D.C. Power Supply : 13.5V±0.2V (over 300mA)

6) Digital Multimeter

1.2. Preliminary Steps

1) Connect the output of Sweamer Generator like <Fig 1>.

Here, set the output of Sweamer Gen. to 100±5dBu.

POWER

SUPPLY

TUNER

SWEEMAR

GENERATOR

ALIGNMENT

SCOPE

TP2

SAW

FILTER

470/0.5W

7.5V

TP11

C122

C508

IC501

LA7674

R591

TP12

L501

VCO COIL

R520

C521

R518

TP4

R507

L506

AFT COIL

Q503

R517

L503

Z502

TP3

L502

12.5V

POWER

SUPPLY

D502

2) Connect H.Scope and Pulse output of Sweamer Generator to H.Input and Marker input of Alignment Scope, respectively.

3) Apply AGC Voltage(D.C.) to TP11 of IC201.(7.5±0.05V)

4) Apply B+ of IC201 to TP12 of R591.(12.0±0.1V)

5) Set VR526(AGC Adjustment) to mechanical center.

1.3. Adjustment

A. VCO

1) Set the vertical range of Alignment Scope to 1V/DIV and

CAL position, and, by applying D.C. 0~9V, do DC

Calibration to place D.C 4.5V point of waveform to center of Screen.

2) Connect the Input terminal of Alignment Scope to TP3(Video Detection Output), and set Vertical Variable Switch to CAL position.

3) Apply AGC Voltage to TP11 of IC201 through 470§to be

7.5±0.05V

4) Adjust L501 so that BEAT appears on 45.75MHz Marker like <Fig 2> If not, adjust again after attenuating output 10

~20dBu.

42.75

B. AFT

1) Connect the Input of Alignment Scope to TP4 with keeping DC voltage of 2pin of IC201.

2) Keep the output of Sweamer Generator 100±5dBu.

3) Adjust L506 so that waveform of Alignment Scope to be that of <Fig 3>.

4) Adjust Vertical Volume of Alignment Scope to place DC level of waveform to center (4.5V) and 45.75MHz Marker to

7.5V¡0.5V.

AFT

2. SIF Adjustment

VCO

2.1. Necessary Instruments

1) Sweamer Generator : can sweep 3~6MHz

2) Plug In Unit : with 4.5MHz Marker

3) Alignment Scope : X-Y mode(can measurable 10mV~

20Vp-p)

4) DC Power Supply : 13.5V, over 300mA

5) DC Power Supply : 0~12V variable

f (MHz)

45.0 47.25

45.75MHz (Turn L105 so that the position of Beat is same with 45.75MHz Marker)

45.75 MARKER

- 1-

2.2. Adjustment

1) Connect Sweamer Generator and Alignment Scope the same method of VIF adjustment.

2) Connect the output of Sweamer Generator to TP5 like <Fig 4 >.

3) Connect the Input of Alignment Scope to TP6.

4) Apply AGC voltage of IC201 to TP11(7.5±0.05V).

5) Apply B+ of IC201 to TP12.

6) Adjust L502 S-shaped waveform of Alignment Scope to be that of <Fig 5>.

Adjust (A=B)

Because 4.5MHz Marker doesn’t with horizontal line, apply (a) marker(4.5MHz) to be the center of (b), (c)Markers.

100% WHITE

75% WHITE

DC POWER

SUPPLY

DC 12V

TP13

R591

TP12

DC POWER

SUPPLY

DC 12.5V

12.5V

POWER

SUPPLY

A = B

POWER

ALIGNMENT

SCOPE

TP6

7.5V

TP11

C508

IC501

LA7674

SWEEMAR

GENERATOR

TP5

C515

C516

Z501

SUPPLY

C509

470/0.5W

L502

SIF COIL

R591

TP12

C206

ZD201

PATTERN

A/V IN

VIDEO

SOUND

R609

GENERATOR

TP8

R210

Q206

IC202

C204

C507

Q603

IC601

COLD

8 7

HOT

VR202

Q201

R618

Q601

Q202

L201

C510

OSCILLOSCOPE

C201

6.0MHz

VIDEO

SOUND

TP10

3.3 Adjustment

Adjust VR202 to get Luminance signal(Color Bar) level like below. ( Refer to <Fig 6> )

1) White 100% modulated 1.78±0.1Vp-p

2) White 75% modulated 1.46±0.1Vp-p

4. Automatic Gain Control(AGC) Adjustment

4.1Turn on a SET and receive Digital Pattern of 65¡1dB through

(b)

(a)

4.5 MARKER

75§Ant. terminal.

4.2 Connect DMM(Digital Multi-Meter) to J27.

4.3 Adjust VR101 to read 5.7±0.05V of DMM. (Where, you can set proper AGC voltage according to signal

condition.)

(c)

3. Composite Video Signal Adjustment

3.1.Necessary Instruments

1) Pattern Generator : PM5518(PHILIPS) or Equivalents 7 Step Color Bar Pattern with 75§out

2) Oscilloscope : VP-5650A or Equivalents can measure over 1.0Vp-p Vertical Freq. : over 4MHz

3) DC Power Supply : 12.2±0.2V/400mA 2EA

3.2. Preliminary Steps

1) Connect the output of Pattern Generator to TP8 like <Fig 7>.

Where, the output of Pattern Generator is 1.0Vp-p.(Point

position “A”)

2) Connect DC Power Supply to TP12 and TP13. Where, devide Ground of TP12 and TP13(HOT/COLD).

3) Connect probe to TP10(point “D”).

- 2-

5. Purity and Convergence Adjustment

This adjustment should be made when a complete re-alignment is required or a new picture tube is installed.

5.1 Purity Adjustment

5.1.1 Necessary instruments and Preliminary steps

1) Pattern Generator : 216/1 or Equivalents

2) Degauss CPT and Cabinet with Degaussing coil.

3) Maximize Contrast level.

4) Pre-adjust the DY.

5.1.2 Adjustment

1) Receive Raster signal(Red).

2) Push the DY to get Picture like <Fig 8>.

3) Adjust 2-pole magnet to place RED center of screen orthogonally.

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