Service Manuals, User Guides, Schematic Diagrams or docs for : LG TV RT-29FA34RB Service Manual Chassi MC-036A
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website:http://biz.LGservice.com
e-mail:http://www.LGEservice.com/techsup.html
COLOR TV
SERVICE MANUAL
CHASSIS : MC-036A
MODEL:RT-29FA34RB
CAUTION
BEFORE SERVICING THE CHASSIS,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
CONTENTS
CONTENTS .............................................................................................. 2
SAFETY PRECAUTIONS .........................................................................3
SERVICING PRECAUTIONS ................................................................... 4
DESCRIPTION OF CONTROLS ...............................................................6
SPECIFICATION .......................................................................................9
ADJUSTMENT INSTRUCTION................................................................11
TROUBLE SHOOTING ............................................................................17
BLOCK DIAGRAM...................................................................................21
EXPLODED VIEW ...................................................................................24
EXPLODED VIEW PARTS LIST ..............................................................25
REPLACEMENT PARTS LIST ................................................................26
SVC. Sheet ..................................................................................................
PRINTED CIRCUIT BOARD ........................................................................
- 2 -
SAFETY PRECAUTIONS
IMPORTANT SAFETY NOTICE
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 X-RADIATION, Shock, Fire, or other Hazards.
Do not modify the original design without permission of manufacturer.
General Guidance Before returning the receiver to the customer,
An isolation Transformer should always be used during always perform an AC leakage current check on the exposed
the servicing of a receiver whose chassis is not isolated from metallic parts of the cabinet, such as antennas, terminals, etc.,
the AC power line. Use a transformer of adequate power rating to be sure the set is safe to operate without damage of
as this protects the technician from accidents resulting in electrical shock.
personal injury from electrical shocks.
Leakage Current Cold Check(Antenna Cold Check)
It will also protect the receiver and it's components from being With the instrument AC plug removed from AC source,
damaged by accidental shorts of the circuitry that may be connect an electrical jumper across the two AC plug prongs.
inadvertently introduced during the service operation. Place the AC switch in the on position, connect one lead of
ohm-meter to the AC plug prongs tied together and touch other
If any fuse (or Fusible Resistor) in this TV receiver is blown, ohm-meter lead in turn to each exposed metallic parts such as
replace it with the specified. antenna terminals, phone jacks, etc.
If the exposed metallic part has a return path to the chassis, the
When replacing a high wattage resistor (Oxide Metal Film measured resistance should be between 1M and 5.2M.
Resistor, over 1W), keep the resistor 10mm away from PCB. When the exposed metal has no return path to the chassis the
reading must be infinite.
Keep wires away from high voltage or high temperature parts. An other abnormality exists that must be corrected before the
receiver is returned to the customer.
Due to high vacuum and large surface area of picture tube,
extreme care should be used in handling the Picture Tube. Leakage Current Hot Check (See below Figure)
Do not lift the Picture tube by it's Neck. Plug the AC cord directly into the AC outlet.
Do not use a line Isolation Transformer during this check.
X-RAY Radiation Connect 1.5K/10watt resistor in parallel with a 0.15uF capacitor
between a known good earth ground (Water Pipe, Conduit, etc.)
Warning: and the exposed metallic parts.
Measure the AC voltage across the resistor using AC
The source of X-RAY RADIATION in this TV receiver is the voltmeter with 1000 ohms/volt or more sensitivity.
High Voltage Section and the Picture Tube. Reverse plug the AC cord into the AC outlet and repeat AC
For continued X-RAY RADIATION protection, the voltage measurements for each exposed metallic part. Any
replacement tube must be the same type tube as specified in voltage measured must not exceed 0.75 volt RMS which is
the Replacement Parts List. 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.
To determine the presence of high voltage, use an accurate
high impedance HV meter. Leakage Current Hot Check circuit
Adjust brightness, color, contrast controls to minimum. AC Volt-meter
Measure the high voltage.
The meter reading should indicate
23.5 !1.5KV: 14-19 inch, 26!1.5KV: 19-21 inch,
29.0!1.5KV: 25-29 inch, 30.0 ! 1.5KV: 32 inch
If the meter indication is out of tolerance, immediate service Good Earth Ground
and correction is required to prevent the possibility of such as WATER PIPE,
To Instrument's CONDUIT etc.
premature component failure. 0.15uF
exposed
METALLIC PARTS
1.5 Kohm/10W
- 3 -
SERVICING PRECAUTIONS
CAUTION: Before servicing receivers covered by this service transistors and semiconductor "chip" components. The
manual and its supplements and addenda, read and follow the following techniques should be used to help reduce the
SAFETY PRECAUTIONS on page 3 of this publication. incidence of component damage caused by static by static
NOTE: If unforeseen circumstances create conflict between the electricity.
following servicing precautions and any of the safety 1. Immediately before handling any semiconductor component
precautions on page 3 of this publication, always follow the or semiconductor-equipped assembly, drain off any
safety precautions. Remember: Safety First. electrostatic charge on your body by touching a known earth
ground. Alternatively, obtain and wear a commercially
General Servicing Precautions available discharging wrist strap device, which should be
1. Always unplug the receiver AC power cord from the AC removed to prevent potential shock reasons prior to
power source before; applying power to the unit under test.
a. Removing or reinstalling any component, circuit board 2. After removing an electrical assembly equipped with ES
module or any other receiver assembly. devices, place the assembly on a conductive surface such as
b. Disconnecting or re-connecting any receiver electrical aluminum foil, to prevent electrostatic charge buildup or
plug or other electrical connection. exposure of the assembly.
c. Connecting a test substitute in parallel with an electrolytic 3. Use only a grounded-tip soldering iron to solder or unsolder
capacitor in the receiver. ES devices.
CAUTION: A wrong part substitution or incorrect 4. Use only an anti-static type solder removal device. Some
polarity installation of electrolytic capacitors may result solder removal devices not classified as "anti-static" can
in an explosion hazard. generate electrical charges sufficient to damage ES devices.
d. Discharging the picture tube anode. 5. Do not use freon-propelled chemicals. These can generate
2. Test high voltage only by measuring it with an appropriate electrical charges sufficient to damage ES devices.
high voltage meter or other voltage measuring device (DVM, 6. Do not remove a replacement ES device from its protective
FETVOM, etc) equipped with a suitable high voltage probe. package until immediately before you are ready to install it.
Do not test high voltage by "drawing an arc". (Most replacement ES devices are packaged with leads
3. Discharge the picture tube anode only by (a) first connecting electrically shorted together by conductive foam, aluminum
one end of an insulated clip lead to the degaussing or kine foil or comparable conductive material).
aquadag grounding system shield at the point where the 7. Immediately before removing the protective material from
picture tube socket ground lead is connected, and then (b) the leads of a replacement ES device, touch the protective
touch the other end of the insulated clip lead to the picture material to the chassis or circuit assembly into which the
tube anode button, using an insulating handle to avoid device will be installed.
personal contact with high voltage. CAUTION:Be sure no power is applied to the chassis or
4. Do not spray chemicals on or near this receiver or any of its circuit, and observe all other safety precautions.
assemblies. 8. Minimize bodily motions when handling unpackaged
5. Unless specified otherwise in this service manual, clean replacement ES devices. (Otherwise harmless motion such
electrical contacts only by applying the following mixture to as the brushing together of your clothes fabric or the lifting
the contacts with a pipe cleaner, cotton-tipped stick or of your foot from a carpeted floor can generate static
comparable non-abrasive applicator; 10% (by volume) electricity sufficient to damage an ES device.)
Acetone and 90% (by volume) isopropyl alcohol (90%-99%
strength) General Soldering Guidelines
CAUTION: This is a flammable mixture. 1. Use a grounded-tip, low-wattage soldering iron and
Unless specified otherwise in this service manual, lubrication appropriate tip size and shape that will maintain tip
of contacts in not required. temperature within the range or 500cF to 600cF.
6. Do not defeat any plug/socket B+ voltage interlocks with 2. Use an appropriate gauge of RMA resin-core solder
which receivers covered by this service manual might be composed of 60 parts tin/40 parts lead.
equipped. 3. Keep the soldering iron tip clean and well tinned.
7. Do not apply AC power to this instrument and/or any of its 4. Thorohly clean the surfaces to be soldered. Use a mall
electrical assemblies unless all solid-state device heat sinks wirebristle (0.5 inch, or 1.25cm) brush with a metal handle.
are correctly installed. Do not use freon-propelled spray-on cleaners.
8. Always connect the test receiver ground lead to the 5. Use the following unsoldering technique
receiver chassis ground before connecting the test receiver a. Allow the soldering iron tip to reach normal temperature.
positive lead. (500cF to 600cF)
Always remove the test receiver ground lead last. b. Heat the component lead until the solder melts.
9. Use with this receiver only the test fixtures specified in this c. Quickly draw the melted solder with an anti-static,
service manual. suction-type solder removal device or with solder braid.
CAUTION: Do not connect the test fixture ground strap to CAUTION: Work quickly to avoid overheating the circuit-
any heatsink in this receiver. board printed foil.
6. Use the following soldering technique.
Electrostatically Sensitive (ES) Devices a. Allow the soldering iron tip to reach a normal
Some semiconductor (solid state) devices can be damaged temperature (500cF to 600cF)
easily by static electricity. Such components commonly are b. First, hold the soldering iron tip and solder the strand
called Electrostatically Sensitive (ES) Devices. Examples of against the component lead until the solder melts.
typical ES devices are integrated circuits and some field-effect
- 4 -
c. Quickly move the soldering iron tip to the junction of the Fuse and Conventional Resistor
component lead and the printed circuit foil, and hold it Removal/Replacement
there only until the solder flows onto and around both the 1. Clip each fuse or resistor lead at top of the circuit board
component lead and the foil. hollow stake.
CAUTION: Work quickly to avoid overheating the circuit 2. Securely crimp the leads of replacement component around
board printed foil. notch at stake top.
d. Closely inspect the solder area and remove any excess 3. Solder the connections.
or splashed solder with a small wire-bristle brush. CAUTION: Maintain original spacing between the replaced
component and adjacent components and the circuit board
IC Remove/Replacement to prevent excessive component temperatures.
Some chassis circuit boards have slotted holes (oblong) through
which the IC leads are inserted and then bent flat against the Circuit Board Foil Repair
circuit foil. When holes are the slotted type, the following Excessive heat applied to the copper foil of any printed circuit
technique should be used to remove and replace the IC. When board will weaken the adhesive that bonds the foil to the circuit
working with boards using the familiar round hole, use the board causing the foil to separate from or "lift-off" the board.
standard technique as outlined in paragraphs 5 and 6 above. The following guidelines and procedures should be followed
whenever this condition is encountered.
Remov
1. Desolder and straighten each IC lead in one operation by At IC Connections
gently prying up on the lead with the soldering iron tip as the To repair a defective copper pattern at IC connections use the
solder melts. following procedure to install a jumper wire on the copper
2. Draw away the melted solder with an anti-static suction- pattern side of the circuit board. (Use this technique only on IC
type solder removal device (or with solder braid) before connections).
removing the IC.
Replacemen 1. Carefully remove the damaged copper pattern with a sharp
1. Carefully insert the replacement IC in the circuit board. knife. (Remove only as much copper as absolutely
2. Carefully bend each IC lead against the circuit foil pad and necessary).
solder it. 2. carefully scratch away the solder resist and acrylic coating
3. Clean the soldered areas with a small wire-bristle brush. (if used) from the end of the remaining copper pattern.
(It is not necessary to reapply acrylic coating to the areas). 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.
"Small-Signal" Discrete Transistor 4. Route the jumper wire along the path of the out-away
Removal/Replacement copper pattern and let it overlap the previously scraped end
1. Remove the defective transistor by clipping its leads as of the good copper pattern. Solder the overlapped area and
close as possible to the component body. clip off any excess jumper wire.
2. Bend into a "U" shape the end of each of three leads
remaining on the circuit board. At Other Connections
3. Bend into a "U" shape the replacement transistor leads. Use the following technique to repair the defective copper
4. Connect the replacement transistor leads to the pattern at connections other than IC Pins. This technique
corresponding leads extending from the circuit board and involves the installation of a jumper wire on the component
crimp the "U" with long nose pliers to insure metal to metal side of the circuit board.
contact then solder each connection.
1. Remove the defective copper pattern with a sharp knife.
Power Output, Transistor Device Remove at least 1/4 inch of copper, to ensure that a
Removal/Replacement hazardous condition will not exist if the jumper wire opens.
1. Heat and remove all solder from around the transistor leads. 2. Trace along the copper pattern from both sides of the
2. Remove the heatsink mounting screw (if so equipped). pattern break and locate the nearest component that is
3. Carefully remove the transistor from the heat sink of the directly connected to the affected copper pattern.
circuit board. 3. Connect insulated 20-gauge jumper wire from the lead of
4. Insert new transistor in the circuit board. the nearest component on one side of the pattern break to
5. Solder each transistor lead, and clip off excess lead. the lead of the nearest component on the other side.
6. Replace heatsink. Carefully crimp and solder the connections.
CAUTION: Be sure the insulated jumper wire is dressed so
Diode Removal/Replacement the it does not touch components or sharp edges.
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.
- 5 -
DECRIPTION OF CONTROLS
All the functions can be controlled with the remote control handset.
Some functions can also be adjusted with the buttons on the front
panel of the set.
Remote control handset
Before you use the remote control handset, please install the bat-
teries. See the next page.
POWER MUTE
1 11 1. POWER
switches the set on from standby or off to standby.
1 2 3
2. NUMBER BUTTONS
4 5 6 switches the set on from standby or directly select a number.
2
7 8 9 3. ARC (Aspect Ratio Control)
changes the picture format.
ARC 0 TV/AV
3 12 4. TURBO SOUND BUTTON
MENU
SOUND PICTURE selects Turbo sound.
4 13 TURBO PICTURE BUTTON
T U R B O OK selects Turbo picture.
14
PR
5. D / E (Programme Up/Down)
VOL VOL selects a programme or a menu item.
5
PR switches the set on from standby.
F / G (Volume Down/Up)
REW PLAY FF
adjusts the volume.
adjusts menu settings.
6 P/STILL STOP REC
6. VCR BUTTONS
control a LG video cassette recorder.
7 I/II SSM LIST
8 15 7. SSM (Sound Status Memory)
PSM SLEEP EYE/ recalls your preferred sound setting.
9 16
TEXT PIP Q.VIEW 17 8. I/II
10 18 selects the language during dual language broadcast.
19 selects the sound output (option).
MIX TIME REVEAL ? MODE M
9. PSM (Picture Status Memory)
SIZE STILL POSITION SCAN i recalls your preferred picture setting.
PR PR SWAP INPUT 10. TELETEXT BUTTONS (option)
These buttons are used for teletext.
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