AKAI LEA-19A08G Service manual

LEA-19A08G

SAFETY

SAFETY PRECAUTIONS

PRECAUTIONS

IMPORTANT

IMPORTANT SAFETY

Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by

in the Schematic Diagram and Replacement Parts List.

It is essential that these special safety parts should be replaced with the same components as recommended in this manual to

prevent Shock, Fire, or other Hazards.

Do not modify the original design without permission of manufacturer.

General

General Guidance

AC power line. Use a transformer of adequate power rating as this protects the technician from accidents resulting in personal

injury from electrical shocks.

inadvertently introduced during the service operation.

If any fuse (or Fusible Resistor) in this TV receiver is blown,replace it with the specified.

Before returning the receiver to the customer, always perform an AC leakage current check on the exposed metallic parts of the

cabinet, such as antennas, terminals, etc., to be sure the set is safe to operate without damage of electrical shock.

Guidance

An isolation Transformer should always be used during the servicing of a receiver whose chassis is not isolated from the

It will also protect the receiver and it's components from being damaged by accidental shorts of the circuitry that may be

When replacing a high wattage resistor (Oxide Metal Film Resistor, over 1W), keep the resistor 10mm away from PCB.

Keep wires away from high voltage or high temperature parts.

SAFETY

SAFETY NOTICE

NOTICE

Leakage

Leakage Current

With the instrument AC plug removed from AC source, connect an electrical jumper across the two AC plug prongs. Place the

AC switch in the on position, connect one lead of ohm-meter to the AC plug prongs tied together and touch other ohm-meter lead

in turn to each exposed metallic parts such as antenna terminals, phone jacks, etc.

If the exposed metallic part has a return path to the chassis, the measured resistance should be between 1M Ω and 5.2M Ω .

When the exposed metal has no return path to the chassis the reading must be infinite.

An other abnormality exists that must be corrected before the receiver is returned to the customer.

Leakage

Plug the AC cord directly into the AC outlet.

capacitor between a known good earth ground (Water Pipe, Conduit, etc.) and the exposed metallic parts.

voltage measured must not exceed 0.75 volt RMS which is corresponds to 0.5mA.

In case any measurement is out of the limits specified, there is possibility of shock hazard and the set must be checked and

repaired before it is returned to the customer.

Current

Current Cold

Leakage

Leakage Current

Do not use a line Isolation Transformer during this check. Connect 1.5K/10watt resistor in parallel with a 0.15uF

Measure the AC voltage across the resistor using AC voltmeter with 1000 ohms/volt or more sensitivity.

Reverse plug the AC cord into the AC outlet and repeat AC voltage measurements for each exposed metallic part. Any

Cold

Cold Check(Antenna

Current

Current Hot

Hot

Hot Check

Check(Antenna

Check(Antenna Cold

Check

Check (See

(See

(See below

Cold

Cold Check

below

below Figure)

Check

Figure)

Leakage

Leakage Current

Current

Current Hot

Hot

Check

Hot

Check

Hot Check

Check circuit

circuit

SERVICING

SERVICING PRECAUTIONS

CAUTION

CAUTION : Before servicing receivers covered by this service manual and its supplements and addenda, read and follow

SAFETY PRECAUTIONS on page 3 of this publication.

NOTE:

NOTE: If unforeseen circumstances create conflict between the following servicing precautions and any of the safety

precautions on page 3 of this publication, always follow the safety precautions. Remember: Safety First.

General

General Servicing

1. Always unplug the receiver AC power cord from the AC power source before;

a. Removing or reinstalling any component, circuit board module or any other receiver assembly.

b. Disconnecting or reconnecting any receiver electrical plug or other electrical connection.

c. Connecting a test substitute in parallel with an electrolytic capacitor in the receiver.

CAUTION

CAUTION : A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in an

explosion hazard.

2. Test high voltage only by measuring it with an appropriate high voltage meter or other voltage measuring device (DVM,

FETVOM , etc) equipped with a suitable high voltage probe. Do not test high voltage by "drawing an arc".

3. Do not spray chemicals on or near this receiver or any of its assemblies.

4. Unless specified otherwise in this service manual, clean electrical contacts only by applying the following mixture to the

contacts with a pipe cleaner, cotton-tipped stick or comparable non-abrasive applicator; 10% (by volume) Acetone and 90%

(by volume) isopropyl alcohol (90%-99% strength)

CAUTION

CAUTION : This is a flammable mixture.

Unless specified otherwise in this service manual, lubrication of contacts in not required.

5. Do not defeat any plug/socket B+ voltage interlocks with which receivers covered by this service manual might be

equipped.

6. Do not apply AC power to this instrument and/or any of its electrical assemblies unless all solid-state device heat sinks ar

correctly installed.

7. Always connect the test receiver ground lead to the receiver chassis ground before connecting the test receiver positive

lead.

Always remove the test receiver ground lead last.

8. Use with this receiver only the test fixtures specified in this service manual.

CAUTION:

CAUTION: Do not connect the test fixture ground strap to any heat sink in this receiver.

Servicing

Servicing Precautions

Precautions

PRECAUTIONS

Electrostatically Sensitive (ES) Devices

Some semiconductor (solid-state) devices can be damaged easily by static electricity. Such components commonly are called

Electrostatically Sensitive (ES) Devices. Examples of typical ES devices are integrated circuits and some field-effect

transistors and semiconductor "chip" components. The following techniques should be used to help reduce the incidence of

component damage caused by static by static electricity.

1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any

electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commercially available

discharging wrist strap device, which should be removed to prevent potential shock reasons prior to applying power to the unit

under test.

2. After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as

aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly

3. Use only a grounded-tip soldering iron to solder or unsolder ES devices.

4. Use only an anti-static type solder removal device. Some solder removal devices not classified as "anti-static" can

generate electrical charges sufficient to damage ES devices.

5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ES devices.

6. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it.

(Most replacement ES devices are packaged with leads electrically shorted together by conductive foam, aluminum foil or

comparable conductive material).

7. Immediately before removing the protective material from the leads of a replacement ES device, touch the protective

material to the chassis or circuit assembly into which the device will be installed.

CAUTION

CAUTION : Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.

8. Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise harmless motion such as the

brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity sufficient

to damage an ES device.)

General

General Soldering

1. Use a grounded-tip, low-wattage soldering iron and appropriate tip size and shape that will maintain tip temperature within

the range or 500 ° F to 600 °

2. Use an appropriate gauge of RMA resin-core solder composed of 60 parts tin/40 parts lead.

3. Keep the soldering iron tip clean and well tinned.

4. Thoroughly clean the surfaces to be soldered. Use a mall wire-bristle (0.5 inch, or 1.25cm) brush with a metal handle.

Do not use freon-propelled spray-on cleaners.

5. Use the following unsoldering technique

a. Allow the soldering iron tip to reach normal temperature. (500 ° F to 600 ° F)

b. Heat the component lead until the solder melts.

c. Quickly draw the melted solder with an anti-static, suction-type solder removal device or with solder braid.

CAUTION

CAUTION : Work quickly to avoid overheating the circuit board printed foil.

6. Use the following soldering technique.

a. Allow the soldering iron tip to reach a normal temperature (500 ° F to 600 ° F)

b. First, hold the soldering iron tip and solder the strand against the component lead until the solder melts.

c. Quickly move the soldering iron tip to the junction of the component lead and the printed circuit foil, and hold it there only

until the solder flows onto and around both the component lead and the foil.

CAUTION

CAUTION : Work quickly to avoid overheating the circuit board printed foil.

d. Closely inspect the solder area and remove any excess or splashed solder with a small wire-bristle brush.

Soldering

Soldering Guidelines

Guidelines

Remove/Replacement

IC Remove/Replacement

Remove/Replacement

Some chassis circuit boards have slotted holes (oblong) through which the IC leads are inserted and then bent flat against the

circuit foil. When holes are the slotted type, the following technique should be used to remove and replace the IC. When working

with boards using the familiar round hole, use the standard technique as outlined in paragraphs 5 and 6 above.

Removal

1. Desolder and straighten each IC lead in one operation by gently prying up on the lead with the soldering iron tip as the solder

melts.

2. Draw away the melted solder with an anti-static suction-type solder removal device (or with solder braid) before removing the

IC.

Replacement

1. Carefully insert the replacement IC in the circuit board.

2. Carefully bend each IC lead against the circuit foil pad and solder it.

3. Clean the soldered areas with a small wire-bristle brush. (It is not necessary to reapply acrylic coating to the areas).

"Small-Signal" Discrete Transistor

Removal/Replacement

1. Remove the defective transistor by clipping its leads as close as possible to the component body.

2. Bend into a "U" shape the end of each of three leads remaining on the circuit board.

3. Bend into a "U" shape the replacement transistor leads.

4. Connect the replacement transistor leads to the corresponding leads extending from the circuit board and crimp the "U" with

long nose pliers to insure metal to metal contact then solder each connection.

Power

Power Output,

Removal/Replacement

1. Heat and remove all solder from around the transistor leads.

2. Remove the heat sink mounting screw (if so equipped).

3. Carefully remove the transistor from the heat sink of the circuit board.

4. Insert new transistor in the circuit board.

5. Solder each transistor lead, and clip off excess lead.

6. Replace heat sink.

Diode

Diode Removal/Replacement

1. Remove defective diode by clipping its leads as close as possible to diode body.

2. Bend the two remaining leads perpendicular y to the circuit board.

3. Observing diode polarity, wrap each lead of the new diode around the corresponding lead on the circuit board.

4. Securely crimp each connection and solder it.

5. Inspect (on the circuit board copper side) the solder joints of the two "original" leads. If they are not shiny, reheat them and if

necessary, apply additional solder.

Fuse

Fuse and

Removal/Replacement

1. Clip each fuse or resistor lead at top of the circuit board hollow stake.

2. Securely crimp the leads of replacement component around notch at stake top.

3. Solder the connections.

CAUTION:

CAUTION: Maintain original spacing between the replaced component and adjacent components and the circuit board to

prevent excessive component temperatures.

Output,

Output, Transistor

Removal/Replacement

and

and Conventional

Transistor

Transistor Device

Conventional

Conventional Resistor

Device

Resistor

Circuit

Circuit Board

Excessive heat applied to the copper foil of any printed circuit board will weaken the adhesive that bonds the foil to the circuit

board causing the foil to separate from or "lift-off" the board. The following guidelines and procedures should be followed

whenever this condition is encountered.

At IC

To repair a defective copper pattern at IC connections use the following procedure to install a jumper wire on the copper pattern

side of the circuit board. (Use this technique only on IC connections).

1. Carefully remove the damaged copper pattern with a sharp knife. (Remove only as much copper as absolutely necessary).

2. carefully scratch away the solder resist and acrylic coating (if used) from the end of the remaining copper pattern.

3. Bend a small "U" in one end of a small gauge jumper wire and carefully crimp it around the IC pin. Solder the IC connection.

4. Route the jumper wire along the path of the out-away copper pattern and let it overlap the previously scraped end of the good

Board

Board Foil

Connections

IC Connections

Connections

Foil

Foil Repair

Repair

copper pattern. Solder the overlapped area and clip off any excess jumper wire.

Other

At Other

Use the following technique to repair the defective copper patternat connections other than IC Pins. This technique involves the

nstallation of a jumper wire on the component side of the circuit board.

1. Remove the defective copper pattern with a sharp knife. Remove at least 1/4 inch of copper, to ensure that a hazardous

condition will not exist if the jumper wire opens.

2. Trace along the copper pattern from both sides of the pattern break and locate the nearest component that is directly

connected to the affected copper pattern.

3. Connect insulated 20-gauge jumper wire from the lead of the nearest component on one side of the pattern break to the lead

of the nearest component on the other side. Carefully crimp and solder the connections.

CAUTION

CAUTION : Be sure the insulated jumper wire is dressed so the it does not touch components or sharp edges.

NOTE

NOTE : Specifications and others are subject to change without notice for improvement.

1. Application range

This specification is applied to the LCD TV used AS-MST6M181VS-LE1 chassis.

2. Requirement for Test

Each part is tested as below without special appointment.

1) Temperature : 25 ± 5 º C (77 ± 9 º F), CST : 40 ± 5 º C

2) Relative Humidity : 65 ± 10%

3) Power Voltage : Standard input voltage(100-240V~, 50/60Hz)

* Standard Voltage of each products is marked by models.

4) Specification and performance of each parts are followed each drawing and specification by part number in accordance with

BOM.

5) The receiver must be operated for about 20 minutes prior to the adjustment.

3. Test method

1) Performance: TV test method followed

2) Demanded other specification

- Safety: CB specification

- EMC: CISPR 13 specification

4. General

Connections

Other

Connections

Other Connections

Connections

General

General specification

specification

SPECIFICATION

Item Specification Remark

Broadcasting system PAL-BG

1) VHF : 00 ~ 12

Available Channel

Tuner IF

Input V oltage 100 - 240V~, 50/60Hz Mark : 240V, 50Hz

Screen Size 18.5 inch Wide (1366 x 768) LC185EXN-SCA1

Aspect Ratio 16:9

Module LC185EXN-SCA1 LC185EXN-SCA1

Operating Environment

Storage Environment

2) UHF : 20 ~ 75

3) CATV : 02 ~ 44

PAL

: 38.90MHz(Picture)

34.40MHz(Sound)

1) Temp : 0 ~ 40 deg

2) Humidity : ~ 80 %

1) Temp : -20 ~ 60 deg

2) Humidity : ~ 85 %

Spec

Chrominance

5. Chrominance

Chrominance &

No Item Min Typ Max Unit Remark

White peak brightness

2 Contrast ratio cd/m2 N/A

3 Brightness uniformity 70 % Full white

4 Color coordinate

5 Color coordinate uniformity N/A

6 Color Gamut 68 %

7 Color Temperature 10000 K

Component

6. Component

Component Video

1 720x480 15.73 59.94 SDTV,DVD 480i

2 720x480 15.75 60 SDTV, DVD 480i

3 720x480 31.47 59.94 SDTV 480p

4 720X480 31.5 60 SDTV 480p

5 720x576 15.625 50 SDTV, DVD 576i

6 720x576 31.25 50 SDTV 576p

7 1280x720 44.96 59.94 HDTV 720p

8 1280x720 45 60.36 HDTV 720p

9 1280x720 37.5 50 HDTV 720p

10 1920x1080 28.125 50 HDTV 1080i

11 1920x1080 33.75 60 HDTV 1080i

12 1920x1080 33.72 59.94 HDTV 1080i

13 1920x1080 56.25 50 HDTV 1080p

14 1920x1080 67.433 59.94 HDTV 1080p

15 1920x1080 67.5 60 HDTV 1080p

RGB

7. RGB

RGB PC

No Resolution H-freq(kHz) V-freq.(Hz) Pixel clock(MHz) Proposed Remark

1 720*400 31.468 70.08 28.321

4 1024*768

5 1280*768 47.78 59.87 79.5 WXGA

6 1360*768 47.72 59.8 84.75 WXGA

INPUT

PC INPUT

INPUT Mode

640*480 31.469 59.94 25.17 VESA Input 848*480 60Hz,

852*480 37.684 75.00 31.50 --> 640*480 60Hz Display

800*600

Luminance

& Luminance

Luminance Specification

Video

Input

Video

Input

Video Input

Input

Mode

Specification

240 300 cd/m2

RED

GREEN

BLUE

WHITE

(Y,

PB,

(Y,

37.879 60.31 40.00 VESA

46.875 75.00 49.50

48.363 60.00 65.00 VESA(XGA)

56.470 70.00 75.00

60.123 75.029 78.75

PR)

PB,

PR)

PB,

PB, PR)

PR)

Resolution H-freq(kHz) V-freq(Hz)

Y 0.344

X 0.327

Y 0.626

X 0.155

Y 0.042

X 0.279

Y 0.292

Typ..

-0.03

Specification

0.620

Typ..

+0.03

LC185EXN-SCA1

Remark

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