MT-42PM13B (CHASSIS:RF-04GC) - LG TV Service Manual (repair manual)

BEFORE SERVICING THE CHASSIS,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

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SAFETY PRECAUTIONS

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

An  isolation Transformer should always be used during
the servicing of a receiver whose chassis is not isolated from
the AC power line. Use a transformer of adequate power rating
as this protects the technician from accidents resulting in
personal injury from electrical shocks.

It will also protect the receiver and it's components from being
damaged by accidental shorts of the circuitry that may be
inadvertently introduced during the service operation.

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

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.

Due to high vacuum and large surface area of picture tube,
extreme care should be used in handling the Picture Tube.
Do not lift the Picture tube by it's Neck.

Leakage Current Cold Check(Antenna Cold Check)

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 1MΩ and 5.2MΩ. 
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 Current Hot Check 

(See below Figure) 

Plug the AC cord directly into the AC outlet.
Do not use a line Isolation Transformer during this check. 
Connect 1.5K/10watt resistor in parallel with a 0.15uF capacitor
between a known good earth ground (Water Pipe, Conduit, etc.)
and the exposed metallic parts.
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
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.

Leakage Current Hot Check circuit

1.5 Kohm/10W

To Instrument's
exposed 
METALLIC PARTS

Good Earth Ground
such as WATER PIPE,
CONDUIT etc.

AC Volt-meter

IMPORTANT SAFETY NOTICE

0.15uF

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- When using the remote control aim it at the remote control sensor of the set.
- There's maybe a defect in consecutive operation of remote control in specified brightness according to this set feature.

POWER

MUTE

INPUT SELECT MULTIMEDIA

LIST

ARC

MENU

PR

PR

VOL

OK

1

2

3

4

5

6

7

PSM

SSM

8

9

0

VOL

SPLIT ZOOM PIP/DW

SLEEP

REVEAL

TEXT/

PIP PR+

WIN. SIZE

MIX

PIP PR-

POSITION

TIME

SWAP

HOLD

INDEX

PIP INPUT

?

 i

I/II

selects the Component, RGB or DVI

modes.

switches the sub picture on or off.

selects PIP or DW modes.

selects a programme for the sub picture.

alternates between main and sub pic-

ture.

selects the input mode for the sub pic-

ture.

adjusts the sub picture size.

moves the sub picture to 

D

D

E

E

or 

F

F

G

G

direction.

POWER
switches the set on from standby or
off to standby.

ARC 
changes the picture format.

MENU
displays on screen menus one by one.
exits the current menu.
memorizes menu changes.

SWAP (option)
returns to the previously viewed pro-
gramme.
Note : This function works only when

SSM
to select the sound appropriate to
your viewing programme character.

SLEEP
sets the sleep timer.

I/II (option)
selects the language during dual lan-
guage broadcast.
selects the sound output.

These buttons are used for teletext.
For further details, see the ‘Teletext’
section.
Note : In teletext mode, the PIP PR
+/-, SWAP and PIP INPUT buttons are
used for teletext function.

displays the programme table.

switches the sound on or off.

D

D

E

E

selects a programme or a menu item.

switches the set on from standby.

F

F

G

G

adjusts the volume.

adjusts menu settings.

accepts your selection or displays the

current mode.

adjusts the factory preset picture

according to the room.

enlarge the screen with regular

ration.