42PG20-UA (CHASSIS:PU84A) - LG TV Service Manual (repair manual)

Model
42PG20-UA (CHASSIS:PU84A)
Pages
49
Size
11.75 MB
Type
PDF
Document
Service Manual
Brand
Device
TV / Plasma
File
42pg20-ua-chassis-pu84a.pdf
Date

View LG 42PG20-UA (CHASSIS:PU84A) Service Manual online

PLASMA TV
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE CHASSIS,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
CHASSIS : PU84A
MODEL : 42PG20        
42PG20-UA
CH
VOL
MENU
INPUT
ENTER
- 2 -
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  lsolation  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  circuitary  that  may  be
inadvertently introduced during the service operation.
If any fuse (or Fusible Resistor) in this monitor is blown, replace
it with the same specified type.
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.
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  positioin,  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  esposed  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 sepcified, 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
CANADA: LG Electronics Canada, Inc. 550 Matheson
Boulevard East Mississauga, Ontario L4Z 4G3
USA      : LG Customer Interactive Center
P.O.Box 240007, 201 James Record Road Huntsville,
AL 35824
Digital TV Hotline  1-800-243-0000
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
- 3 -
SPECIFICATIONS.................................................................4
ADJUSTMENT INSTRUCTIONS ..........................................5
TROUBLE SHOOTING GUIDE ...........................................11
BLOCK DIAGRAM...............................................................41
EXPLODED VIEW...............................................................44
EXPLODED VIEW PARTS LIST .........................................45
SCHEMATIC DIAGRAM..........................................................
PRINTED CIRCUIT BOARDS .................................................
TABLE OF CONTENTS
- 4 -
The specifications shown above may be changed without prior notice for quality improvement.
MODELS
AC100-240V ~ 50/60Hz
NTSC-M, ATSC, 64 & 256 QAM
VHF 2-13, UHF 14-69, CATV 1-135, DTV 2-69, CADTV 1-135
75 ohm
32 ~ 104°F (0 ~ 40°C)
Less than 80%
-4 ~ 140°F (-20 ~ 60°C)
Less than 85%
Dimensions
(Width x Height x Depth)
Weight
Power requirement
Television System
Program Coverage
External Antenna
Impedance
Environment condition
With stand
Without stand
With stand
Without stand
Operating
Temperature
Operating Humidity
Storage Temperature
Storage Humidity
42PG20 (42PG20-UA)
42PG20C (42PG20C-UA)
50PG20 (50PG20-UA)
50PG20C (50PG20C-UA)
MODELS
50PG30
(50PG30F-UA)
60PG30
(60PG30F-UA)
41.3 x 30.2 x 12.2 inches
1048.0 x 766.0 x 310.0 mm
41.3 x 28.1 x 3.3 inches
1048.0 x 713.0 x 83.5 mm
61.7 pounds / 28.0 kg
54.2 pounds / 24.6 kg
48.9 x 34.9 x 14.6 inches
1242.0 x 887.6 x 370.0 mm
48.9 x 32.6 x 3.5 inches
1242.0 x 827.2 x 88.0 mm
86.6 pounds / 39.3 kg
76.3 pounds / 34.6 kg
Dimensions
(Width x Height x Depth)
Weight
With stand
Without stand
With stand
Without stand
48.9 x 34.9 x 14.6 inches
1242.0 x 887.6 x 370.0 mm
48.9 x 32.6 x 3.5 inches
1242.0 x 827.2 x 88.0 mm
86.6 pounds / 39.3 kg
76.3 pounds / 34.6 kg
57.3 x 38.8 x 16.3 inches
1455.0 x 985.0 x 414.0 mm
57.3 x 38.5 x 15.8 inches
1455.0 x 914.8 x 82.8 mm
137.6 pounds / 62.4 kg
127.8 pounds / 58.0 kg
MODELS
50PG60
(50PG60F-UA)
60PG60
(60PG60F-UA)
Dimensions
(Width x Height x Depth)
Weight
With stand
Without stand
With stand
Without stand
48.9 x 34.9 x 14.6 inches
1242.0 x 887.6 x 370.0 mm
48.9 x 32.6 x 3.5 inches
1242.0 x 827.2 x 88.0 mm
86.6 pounds / 39.3 kg
76.3 pounds / 34.6 kg
57.3 x 38.8 x 16.3 inches
1455.0 x 985.0 x 414.0 mm
57.3 x 38.5 x 15.8 inches
1455.0 x 914.8 x 82.8 mm
137.6 pounds / 62.4 kg
127.8 pounds / 58.0 kg
SPECIFICATIONS
- 5 -
ADJUSTMENT INSTRUCTIONS
1. Application Range
This spec. sheet is applied to all of the PU84A chassis.
2. Specification
(1) Because this is not a hot chassis, it is not necessary to use
an isolation transformer. However, the use of isolation
transformer will help protect test instrument.
(2) Adjustment must be done in the correct order.
(3) The adjustment must be performed in the circumstance of
25±5
c
C of temperature and 65±10% of relative humidity if
there is no specific designation.
(4) The input voltage of the receiver must keep 100~240V,
50/60Hz.
Caution : 42PG20-UA must keep 100 ~ 120V, 50/60Hz.
(5) The receiver must be operated for about 15 minutes prior
to the adjustment.
O
After RGB Full White in HEAT-RUN Mode, the receiver must
be operated prior to the adjustment.
O
Enter into HEAT-RUN MODE
(1) Press the POWER ON KEY on R/C for adjustment.
(2) Press the ADJ KEY on R/C and enter EZ ADJUST
Select “4. White Pattern” by using 
D
/
E
(CH +/-) and press
ENTER(
V
)
Select “White” by using 
F
/
G
(VOL +/-) and press
ENTER(
V
)
- Set is activated HEAT run without signal generator in this
mode.
- Single color pattern ( RED / BLUE / GREEN ) of HEAT RUN
MODE uses to check panel.
Caution: If you turn on a still screen more than 20 minutes
(Especially digital pattern, cross hatch pattern), an after
image may be occur in the black level part of the
screen.
3. Download
(1) Execute ISP program “Mstar ISP Utility” and then click
“Config” tab.
(2) Set as below, and then click “Auto Detect” and check “OK”
message If display “Error”, Check connect computer, jig,
and set.
(3) Click “Connect” tab. If display “Can’t” , Check connect
computer, jig, and set.
(4) Click “Read” tab, and then load download file(XXXX.bin)
by clicking “Read”
(5) Click “Auto” tab and set as below
(6) Click “Run”.
(7) After downloading, check “OK” message.
- 6 -
4. ADC Process
4-1. PC Input ADC
(1) Auto RGB Gain/Offset Adjustment
1) Convert to PC in Input-source
I2C COMMAND: 0xF4 (SELECT_INPUT) 0x00 0x60
(RGB)
cf. 0x10(TV), 0x20(AV), 0x40(COMPONENT),
0x60(RGB), 0x90(HDMI)
2) Signal equipment displays
Output Voltage  :  700  mVp-p
Impress Resolution XGA (1024 x 768 @ 60Hz) 
Model : 60    in Pattern Generator
Pattern : 65   in Pattern Generator (MSPG-925 SERISE) 
[gray pattern that left & right is black and center is white
signal (Refer below picture)]. 
3) Adjust by commanding AUTO_COLOR_ADJUST(0xF1)
0x00 0x02 instruction.
(2) Confirmation
1) We confirm whether “0xB6(RGB)” address of EEPROM
“0xA2” is “0xAA” or not. 
2) If “0xB6(RGB)” address of EEPROM “0xB2” isn’t “0xAA”,
we adjust once more
3) We can confirm the ADC values from
“0xB0~0xB5(RGB)” addresses in a page “0xA2”
[
Manual ADC process using Service Remocon. After enter
Service Mode by pushing “ADJ” key, execute “ADC Adjust” by
pushing “
G
” key at “0. ADC CALIBRATION “. 
4-2. COMPONENT Input ADC
(1) Component Gain/Offset Adjustment
1) Convert to Component in Input-source
I2C COMMAND : 0xF4 (SELECT_INPUT)  0x00  0x40
(COMPONENT)
cf. 0x10(TV), 0x20(AV), 0x40(COMPONENT),
0x60(RGB), 0x90(HDMI)
2) Signal equipment displays
Impress Resolution  480i
MODEL : 209   in Pattern Generator(480i Mode)
PATTERN : 65  in Pattern Generator(MSPG-925 SERISE) 
3) Adjust by commanding AUTO_COLOR_ADJUST(0xF1)
0x00 0x02 instruction
4) Signal equipment displays
Impress Resolution  1080i
MODEL : 223   in Pattern Generator(1080i Mode)
PATTERN : 65  in Pattern Generator(MSPG-925 SERISE)
5) Adjust by commanding AUTO_COLOR_ADJUST(0xF1)
0x00 0x02 instruction
[
Manual ADC process using Service Remocon. After enter
Service Mode by pushing “ADJ” key, execute “ADC Adjust” by
pushing “
G
” key at “0. ADC CALIBRATION”. 
ADJUSTMENT INSTRUCTIONS
Adjustment pattern (RGB, COMPONENT)
- 7 -
4-3. Confirmation
(1) We confirm whether “0xBF(480i)/0xC8(1080i)” address of
EEPROM “0xA2” is “0xAA” or not. 
(2) If “0xBF(480i)/0xC8(1080i)” address of EEPROM “0xA2”
isn’t “0xAA”, we adjust once more
(3) We can confirm the ADC values from “0xB9 ~ 0xBE(480i) /
0xC2 ~ (1080i)” addresses in a page “0xA2”
[
Manual ADC Confirmation using Service Remocon. After enter
Service Mode by pushing “INSTART” key.
Caution: Each PCB assembly must be checked by check JIG set.
(Because power PCB Assembly damages to PDP
Module, especially be careful)
Caution: Set up “RF mode(noise)” before voltage adjustment.
5. POWER PCB Ass’y Voltage 
Adjustment
(Va, Vs voltage Adjustment)
5-1. Test Equipment:
D.M.M 1EA
5-2. Connection Diagram for Measuring
Refer to Fig.1, Fig 2
5-3. Adjustment Method 
(1) 50” Va Adjustment (refer fig.1)
1) After receiving 100% Full White Pattern, HEAT RUN.
2) Connect + terminal of D.M.M. to Va pin of P802,
connect-terminal to GND pin of P802.
3) After turning VR902,voltage of D.M.M adjustment as
same as Va voltage which on label of panel right/top
(deviation; ±0.5V)
(2) 50” Vs Adjustment (refer fig.1)
1) Connect + terminal of D.M.M. to Vs pin of P802, connect
-terminal to GND pin of P802.
2) After turning VR901, voltage of D.M.M adjustment as
same as Vs voltage which on label of panel right/top
(deviation ; ±0.5V)
(3) 42” Va Adjustment (refer fig.2)    
1) After receiving 100% Full White Pattern, HEAT RUN.
2) Connect + terminal of D.M.M. to Va pin of P811, connect
-terminal to GND pin of P811.
3) After turning VR901,voltage of D.M.M adjustment as
same as Va voltage which on label of panel right/top
(deviation; ±0.5V)
(4) 42” Vs Adjustment (refer fig.2)
1) Connect + terminal of D. M..M. to Vs pin of P811,
connect -terminal to GND pin of P811.
2) After turning VR951, voltage of D.M.M adjustment as
same as Vs voltage which on label of panel right/top
(deviation ; ±0.5V)
ADJUSTMENT INSTRUCTIONS
(Fig. 1) 50inch Power PCB Assy Voltage Adjustment
(Fig. 2) 42inch Power PCB Assy Voltage Adjustment
- 8 -
6. DDC EDID Write 
(MODEL NAME:  LG TV)
Caution: Press the POWER ON KEY on R/C before EDID download.
EDID download is processed automatically through RS-232C
PC(for communication through RS-232C), UART baud rate:
115200 bps
O
EDID Download Protocol (RS-232C)
O
HDMI-1 EDID DATA
O
HDMI-2 EDID DATA
O
HDMI-3 EDID DATA
O
RGB EDID DATA
ADJUSTMENT INSTRUCTIONS
- 9 -
7. Adjustment of White Balance
Caution: Press the POWER ON KEY on R/C before W/B adjustment.
7-1. Test Equipment
- Color Analyzer (CS-1000, CA-100+(CH.10), CA-210(CH.10))
[
Please adjust CA-100+ / CA-210 by CS-1000 before measuring
--> You should use Channel 10 which is Matrix compensated
(White, Red, Green, Blue revised) by CS-1000 and adjust
in accordance with White balance adjustment coordinate.
O
Color temperature standards according to CSM and Module 
O
Change target luminance and range of the Auto adjustment
W/B equipment.
O
White balance adjustment coordinate and color temperature
7-2. Connecting Picture of the Measuring 
Instrument
(On Automatic control )
Inside PATTERN is used when W/B is controlled. Connect to
auto controller or push control R/C ADJ Key—> Enter the
mode of White-Balance, the pattern will come out.
7-3. Auto-control Interface and Directions
(1) Adjust in the place where the influx of light like floodlight
around is blocked. (illumination is less than 10ux).
(2) In case of PDP: Measure and adjust after sticking the Color
Analyzer (CA-100+, CA210) to the side of the module. 
In case of LCD: Adhere closely  the Color Analyzer (
CA210 ) to the module less than 10cm distance, keep it
with the surface of the Module and Color Analyzer’s Prove
vertically.(80~100°).
(3) Aging time  
1) After aging start, keep the power on (no suspension of
power supply) and heat-run over 15 minutes.
2) In case of PDP, keep white pattern using inside pattern.
3) In case of LCD, using ’no signal’ or ‘full white pattern’ or
the others, check the back light on.
O
Auto Adjustment Map(RS-232C)
7-4. Manual White Balance 
1) Press the ADJ KEY on R/C and enter EZ ASJUST
Select “3. Test Pattern” by using 
D
/
E
(CH +/-) and press
ENTER(
V
)
Select “White” by using 
F
/
G
(VOL +/-) and press
ENTER(
V
) and heat run over 15 minutes.
2) Zero Calibrate CA-100+ / CA-210, and when controlling,
stick the sensor to the center of PDP module surface.
3) Press the ADJ KEY on R/C and enter EZ ASJUST
Select “2. White Balance” and press 
G
(VOL +)
Set test-pattern on and display inside pattern. 
4) Control is carried out on three color temperatures, COOL,
MEDIUM, WARM. 
(Control is carried out three times)
<Temperature: COOL>
- R-Cut / G-Cut / B-Cut is set to 64
- Control R-Gain and G-Gain.
- Each gain is limited to 192
<Temperature: MEDIUM>
- R-Cut / G-Cut / B-Cut is set to 64
- Control R-Gain and G-Gain.
- Each gain is limited to 192
ADJUSTMENT INSTRUCTIONS
- 10 -
<Temperature: WARM>
- R-Cut / G-Cut / B-Cut is set to 64
- Control G-Gain and B-Gain.
- Each gain is limited to 192
8. HDCP(High-Bandwidth Digital
Contents Protection) SETTING
(1) Connect D-sub Signal Cable to D-Sub Jack
(2) Input HDCP key with HDCP-key- in-program
(3) HDCP Key value is stored on EEPROM(AT24C512) which
is 80~A1 addresses of  0xA0~0xA2 page
(4) AC off/ on and on HDCP button of MSPG925 and confirm
whether picture is displayed or not of using MSPG925
(5) HDCP Key value is different among the sets. 
9. RS-232C 
Press In-start key and select 3.Baud Rate menu. Check RS-
232C after changing Baud Rate 115200.
10. OPTION
(1) Press ADJ R/C In-start key and select 0.AREA OPTION
(2) Select Country by using 
F
/
G
(VOL +/-) in accordance with
destination
ADJUSTMENT INSTRUCTIONS

Download LG 42PG20-UA (CHASSIS:PU84A) Service Manual (Repair Manual)

Here you can view online and download LG 42PG20-UA (CHASSIS:PU84A) Service Manual in PDF. 42PG20-UA (CHASSIS:PU84A) service manual will guide through the process and help you recover, restore, fix, disassemble and repair LG 42PG20-UA (CHASSIS:PU84A) Plasma. Information contained in service manuals typically includes schematics / circuit diagrams, wiring diagrams, block diagrams, printed wiring boards, exploded views, parts list, disassembly / assembly, pcb.