Mitsubishi Electric LT-2220 User manual

MITSUBISHI DIGITAL ELECTRONICS AMERICA, INC.
9351 Jeronimo Road, Irvine, CA 92618-1904
Copyright © 2004 Mitsubishi Digital Electronics America, Inc.
All Rights Reserved
CAUTION:
Before servicing this chassis, it is important that the service person read the "SAFETY PRECAUTIONS" and
"PRODUCT SAFETY NOTICE" contained in this manual.
MITSUBISHI ELECTRIC
Service
Manual
2003-2004
SPECIFICATIONS
LIQUID CRYSTAL DISPLAY TELEVISION
• Power : [LT-2220, LT-2240] AC ADAPTOR
In - AC 120V, 60Hz; Out - 20VDC 6.0A
: [LT-3020, LT-3040, LT-3050] 120V, 60Hz, 2.2A
• LCD Panel : Resolution - 1280X768
: Pixel Pitch - [LT-2220, LT-2240] 0.375mm
[LT-3020, LT-3040, LT-3050] 0.5025mm
• Analog Inputs : VHF/UHF 75Ω unbalanced
: Two A/V Inputs (Composite or S-Video)
L-R Audio
: Two Component Video Inputs (480i/480p/
720p/1080i) L-R Audio
: PC Input - 60Hz (VGA,S-VGA,XGA,W-XGA)
: PC Audio - 3.5mm Mini-Jack
•Digital Input : MonitorLink™/DVI (Video Sources Only)
L-R Audio (Analog)
: MonitorLink™ Control/RS-232C
•Audio Outputs : L-R Audio Output (Fixed/Variable)
: Headphone Jack (Variable) 3.5mm
• Tuning : NTSC 181Channel Analog Cable
• Frequency Range : VHF 54 ~ 470MHz
UHF 470 ~ 806MHz
• Speakers : [LT-2220, LT-2240]
Left & Right (2 X 2.3W) Sub (3.4W)
: [LT-3020, LT-3040, LT-3050]
Left & Right (2 X 3.5W) Sub (6W)
LT-2220
LT-2240
LT-3020
LT-3040
LT-3050
• Weight and dimensions shown are approximate.
• Design specifications are subject to change without notice.
With Stand: Height Width Depth Weight
[LT-22XX] 20-1/4" 22-3/4" 11-7/8" 36.6 lbs
[LT-30XX] 25-3/8" 29-3/4" 11-7/8" 54.3 lbs
W/O Stand: Height Width Depth Weight
[LT-22XX] 18-5/8" 22-3/4" 4" 19.8 lbs
[LT-30XX] 23-1/4" 29-3/4" 5" 37.5 lbs
• Weight / Cabinet Dimensions

MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050
Page 3
INTRODUCTION .................................................................................................................................. 5
PRODUCT SAFETY NOTICE ............................................................................................................... 5
SAFETY PRECAUTIONS ..................................................................................................................... 5
DISASSEMBLY
LT-22XX ............................................................................................................................................. 7
LT-30XX ........................................................................................................................................... 13
ELECTRICAL ADJUSTMENTS
Initial Setup .................................................................................................................................... 21
CIRCUIT EXPLANATIONS & BLOCK DIAGRAMS
Circuit Explanations ....................................................................................................................... 23
Block Diagrams.............................................................................................................................. 29
TEST POINT LOCATIONS AND DESCRIPTIONS
PWB-SET Test Point Locations and Description ............................................................................ 33
PWB-MAIN Test Point Locations and Description .......................................................................... 35
TROUBLESHOOTING
LT-22XX Power Troubleshooting ...................................................................................................... 37
LT-30XX Power Troubleshooting ...................................................................................................... 39
Video Troubleshooting .................................................................................................................... 41
Audio Troubleshooting .................................................................................................................... 51
Remote Control & Front Switch Troubleshooting ............................................................................ 53
REPLACEMENT PARTS
Replacement Parts List .................................................................................................................. 55
INTERCONNECT WIRING DIAGRAM
CONTENTS

Page 4
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 5
PRODUCT SAFETY NOTICE
Many electrical and mechanical parts in television receivers have special safety related characteristics. These
characteristics are often not evident from visual inspection nor can the protection afforded by them necessarily be
obtained by using replacement components rated for higher voltage, wattage, etc.
Replacement parts which have special safety characteristics are identified in this service manual.
The replacement for any safety part should be identical in value and characteristics.
SAFETY PRECAUTIONS
NOTICE: Observe all cautions and safety related notes located inside the receiver cabinet and on the
receiver chassis.
WARNING:
1. Operation of this receiver outside the cabinet or with the cover removed presents a shock hazard
from the receiver's power supplies. Work on the receiver should not be attempted by anyone who is
not thoroughly familiar with the precautions necessary when working on high voltage equipment.
2. Do not install, remove or handle the LCD panel in any manner unless shatterproof goggles are
worn. People not so equipped should be kept away while the panel is being handled. Keep
the panel away from the body while handling.
3. When service is required, observe the original lead dress. Where a short-circuit has occurred, replace
those components that indicate evidence of overheating.
Leakage current check
Before returning the receiver to the customer, leakage current should be measured using following methods.
1. Cold Check
With the alternating current (AC) plug removed from the AC source, place a jumper across the two AC plug
prongs. Connect one lead of an ohm meter to the AC plug and touch the other lead to each exposed metal part
(i.e. antennas, handle bracket, metal cabinet, screw heads, metal overlay, control shafts, etc.), particularly any
exposed metal part that has a return path to the chassis. The resistance of the exposed metal parts having a
return path to the chassis should be a minimum of 1Mega Ohm. Any resistance below this value indicates
an abnormal condition and requires corrective action.
2. Hot Check ...Use the circuit shown below to perform the hot check test.
1. Keep switch S1 open and connect the receiver to the measuring circuit. Immediately after
connection, and with the switching devices of the receiver in their operating positions, measure
the leakage current for both positions of switch S2.
2. Close switch S1, energizing the receiver. Immediately after closing switch S1, and with the
switching devices of the receiver in their operating positions, measure the leakage current for both
positions of switch S2. Repeat the current measurements of items 1 and 2 after the receiver has
reached thermal stabilization. The leakage current must not exceed 0.5 milliampere (mA).
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 6
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 7
Remove the screws and components in the quantities indicated.
Reassemble in reverse order.
DISASSEMBLYPROCEDURE (LT-22XX)
1. COVER, REAR 2. STAND UNIT
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 8
3. BACK UNIT
4. BACK COVER
DISASSEMBLYPROCEDURE (LT-22XX) CONTINUED
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 9
5. PWB-SET
6. PWB-MAIN
DISASSEMBLYPROCEDURE (LT-22XX0) CONTINUED
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 10
7. CHASSIS BASE
DISASSEMBLYPROCEDURE (LT-22XX) CONTINUED
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 11
8. LCD
9. PANEL
DISASSEMBLYPROCEDURE (LT-22XX) CONTINUED
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 12
WIRING HARNESS LOCATIONS
DISASSEMBLYPROCEDURE (LT-22XX) CONTINUED
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 13
DISASSEMBLYPROCEDURE (LT-30XX)
Remove the screws and components in the quantities indicated.
Reassemble in reverse order.
1. COVER, REAR
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 14
DISASSEMBLYPROCEDURE (LT-30XX) CONTINUED
3. BACK COVER
2. STAND UNIT
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 15
DISASSEMBLYPROCEDURE (LT-30XX) CONTINUED
5. BRACKET, VESA
4. UNIT SPEAKER
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 16
DISASSEMBLYPROCEDURE (LT-30XX) CONTINUED
6. SHIELD, POWER & SHIELD, CASE
7. COVER, TERMINAL, LEFT & RIGHT
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 17
DISASSEMBLYPROCEDURE (LT-30XX) CONTINUED
8. ASSY-PWB-MAIN/ASSY-PWB-SET/UNIT-POWER
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 18
DISASSEMBLYPROCEDURE (LT-30XX) CONTINUED
9. CHASSIS, REAR
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 19
DISASSEMBLYPROCEDURE (LT-30XX) CONTINUED
10. BRACKET T/B/LCD PANEL
11. BEZEL
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050

Page 20
DISASSEMBLYPROCEDURE (LT-30XX) CONTINUED
WIRING HARNESS LOCATIONS
MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050