Akira LCT-20HSST Schematic

LCT TV

Service Manual

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MODEL:

LCT-20HSST

Model No.: LCT-20HSST
Version: 1.0

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CONTENTS

SAFE PRECAUTION.............................................................................................................................. 4

BLOCK DIAGRAM ................................................................................................................................5

MAIN BOARD ........................................................................................................................................6

FACTORY MODE ADJUSTMENT ........................................................................................................ 7

TROUBLESHOOTING ......................................................................................................................... 10

HOW TO UPDATE THE SOFTWARE .................................................................................................12

CIRCUIT DIAGRAM............................................................................................................................ 13

PART LIST............................................................................................................................................. 28

Model No.: LCT-20HSST
Version: 1.0

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SAFETY PRECAUTION

WARNING:

Service should not be attempted by anyone unfamiliar with the necessary precaution on this receiver.

The following are the necessary precautions to be observed before servicing this chassis.

1. When replacing a chassis in the cabinet, always be certain that all the protective devices are put

back in place, such as: non-metallic control knobs, insulating covers, shields, isolation

resistor-capacitor network etc.

2. When replacing parts or circuit boards, disconnect the power cord.

3. When replacing a high wattage resistor (oxide metal film resistor) on the circuit board, keep the

resistor 10mm (1/2in) away from circuit board.

4. Connection wires must be kept away from components with high voltage or high temperature.

5. If any fuse in this TV receiver is blown, replace it with the FUSE specified in the chassis parts list.

PRODUCT SAFETY NOTICE

Many electrical and mechanical parts in the chassis have special safety-related characteristics.

These characteristics are often passed unnoticed by a visual inspection.

Replacement parts, which have these special safety characteristics are identified in this manual and its

supplement electrical components having such features are shaded on the schematic diagram and the

parts list.

Before replacing any of these components, read the parts list in this manual carefully. The use of

substitute replacement parts which do not have the same characteristic as specified in the parts list may

create shock, fire or other hazards.

Model No.: LCT-20HSST
Version: 1.0

BLOCK DIAGRAM

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Model No.: LCT-20HSST
Version: 1.0

MAIN BOARD

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Model No.: LCT-20HSST
Version: 1.0

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FACTORY MODE ADJUSTMENT

FACTORY MODE adjustment is a special adjustment, which is controlled by I

been set at optimum mode at the factory. Except for special request, such as updating software, replacing

PANEL, MEMORY, IC etc., it is hoped not to be adjusted after produced. To conduct FACTORY

MODE's adjustment, please do it according to the following steps:

1) Press the MUTE button and the number button [2、6、6、0、7、1] on the remote controller to

enter into factory menu, adjust display, cal., stv2248 or other menu. You can use navigation

key to access them.

2) In display menu, display the basic characteristic parameter such as panel resolution, mode

table, power on time, backlight on time, software version number etc.

3) In cal. menu, display the basic characteristic parameter such as external comb filter, video

format, color space, test pattern etc. Except for special need, reset nvram item and right to OK

set item are hoped not to be adjusted.

4) In stv2248 menu, select the item you want to adjust by pressing the button “ CH+” or “CH-” and

use the "VOL+" or "VOL-" button to adjust. In this menu, you can adjust the white balance,

picture modes value, SCART Audio out value and volume middle value. And the contrast value,
AGC value and the important value vcofine, vcocoa are in the sub menu 2248 adjust.

5) In OTHER menu, select the item you want to adjust by pressing the button “ CH+”or

“CH-”such as sharpness adjust, Volume Max and Volume Min value and use the "VOL+" or
"VOL-" button to adjust.

6) Press "MENU" button on the remote controller to exit the FACTORY MODE.

Page 1: Display the different characteristic parameter according to signal source and TV set model.

Item Name Default Value Note

1 Panel 640 x 480

2 Mode table

3 Power on time

4 Backlight on time

5 Version number

C BUS. The TV set has

2

Model No.: LCT-20HSST
Version: 1.0

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Page 2: Display the basic default setting according to signal source.

Item Name Default Value Note

1 External comb filter on On, off

2 Video space auto NTSC, PAL, SECAM,

NTSC Japan, Auto

3 Color space

4 Test pattern None Color bar, black, gray,

5 Calibration Useless

6 Reset nvram Used for test in

7 Right to OK setting Used for test in

Page 3: Set the default value of brightness and contrast as following table.

Item Description Default Value Note

2248 contrast IC 2248 contrast value 19 0~63

2248 bright IC 2248 bright value 32 0~63

2248 vcofine IC 2248 vco fine value 0~128 Depends on

2248 vcocoa IC 2248 vco coarse value 0~15 Depends on

2248 AGC Auto gain control value 24 0~64

2248 auto vco Automatically adjust vco value

2248 manual vco Manually adjust vco value

Wb manual adj Manually adjust white balance

Wb auto adj Automatically adjust white balance Used for test in

Wb state preset White balance state value Used for test in

Pct mode setting Picture modes value of different source

SCRT Audio out Audio amplitude value 96 80~116

Volume Middle Middle value of volume 100 0~127

RGB Only for tv, video,

Ypbpr smpte240

White, red, green, blue

gradient, blue gradient

s-video, RGB source

Only for

YPbPr/YcbCR

Used for test in

factory

factory.

factory

hardware

hardware

factory

factory

Model No.: LCT-20HSST
Version: 1.0

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Set the default value of picture mode item as following table.

Single source Pct mode status Brightness Contrast Note

VIDEO

YUV

RGB

Page 4: Set the default value of volume and white balance adjustment as following table.

Name Description Default Value Note

Sharpness Sharpness of TV & video picture Sofetest Normal, soft, sharp,

Pw brt max video IC PW1306 max bright for video 35 0~127

Pw cnt max video IC PW1306 max contrast for video 65 0~255

Pw cnt max yuv IC PW1306 max bright yuv 55 0~127

Pw cnt max yuv IC PW1306 max contrast for yuv 85 0~225

Pw brt max rgb IC PW1306 max bright for rgb 55 0~127

Pw cnt max rgb IC PW 1306 max contrast for rgb 85 0~255

Volume Max Volume maximum value 110 0~127

Volume Min Volume minimum value 60 0~127

Dynamic 81 80

Standard 71 70

Soft 60 60

Dynamic 81 69

Standard 71 59

Soft 60 49

Dynamic 60 60

Standard 50 50

Soft 50 29

sharpest, softest

Model No.: LCT-20HSST
Version: 1.0