Mitsubishi Electric LT-3280 User manual

MITSUBISHI DIGITAL ELECTRONICS AMERICA, INC.
9351 Jeronimo Road, Irvine, CA 92618-1904
Copyright © 2005 Mitsubishi Digital ElectronicsAmerica, Inc.
AllRightsReserved
CAUTION:
Before servicing this chassis, it is important that the service person read the "SAFETY PRECAUTIONS" and
"PRODUCTSAFETYNOTICE"containedinthismanual.
MITSUBISHIELECTRIC
SerSer
SerSer
Servicevice
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ManualManual
ManualManual
Manual
20052005
20052005
2005
SPECIFICATIONS
LIQUID CRYSTAL DISPLAY TELEVISION
LT-3280 (LT-3280D)
LT-3780 (LT-3780D)
• Weightanddimensionsshownare approximate.
• Design specifications are subject to change without notice.
• HDMI™isatrademark of HDMI Licensing, LLC
• Power : AC 120V, 60Hz
[LT-3280D] 200W
[LT-3780D] 300W
Standby <5W
• LCD Panel : Size/Resolution -
[LT-3280D] 32" diagonal, 16:9 / 1366x768
[LT-3780D] 37" diagonal, 16:9 / 1920x1080
: Pixel Pitch -
[LT-3280D] 0.519mm x 0.173mm x RGB
[LT-3780D] 0.4275mm x 0.1425mm x RGB
•Input Jacks : MonitorLink™Audio/Video - HDMI™
: MonitorLink™ Control - RS-232C
: PC Video - VGA /Mini D-sub 15 pin
: PC Audio - 3.5mm Mini-Jack
• Speakers : 2 Way Bass Reflex Left & Right (2 X 5W)
TheLT-3280includestheLT-3280D,monitorand HD-4001,receiver/controller.
TheLT-3780includestheLT-3780D,monitorand HD-4001,receiver/controller.
Thismanualcovers theLT-3280Dand LT-3780D,monitors.
Forthereceiver/controller,seethe HD-4001 Service Manual.
LT-3280D
With Stand: Height Width Depth Weight
25.4" 32.4" 12.8" 68.0 lbs
W/O Stand: Height Width Depth Weight
22.9" 32.4" 5.0" 44.3 lbs
LT-3780D
With Stand: Height Width Depth Weight
28.5" 37.3" 12.8" 80.0 lbs
W/O Stand: Height Width Depth Weight
26.0" 37.3" 5.3" 57.3 lbs
•Cabinet Dimensions/ Weight

MODELS: LT-3280D/LT-3780D
Page 3
CONTENTS
PRODUCTSAFETY NOTICE &SAFETY PRECAUTIONS..................................................................5
DISASSEMBLY
Disassembly & PanelReplacement ................................................................................................7
LT-3280WireDressing .................................................................................................................. 23
LT-3780WireDressing .................................................................................................................. 24
ELECTRICALADJUSTMENTS
InitialSetup................................................................................................................................... 25
CIRCUITEXPLANATIONS & BLOCKDIAGRAMS
CircuitExplanations...................................................................................................................... 27
BlockDiagrams ............................................................................................................................ 32
TROUBLESHOOTING
PowerTroubleshooting .................................................................................................................. 35
VideoTroubleshooting................................................................................................................... 38
AudioTroubleshooting................................................................................................................... 40
RemoteControl Troubleshooting ................................................................................................... 42
FrontSwitchTroubleshooting ........................................................................................................ 43
REPLACEMENTPARTS
LT-3280ReplacementPartsList.................................................................................................... 44
LT-3780ReplacementPartsList.................................................................................................... 45
SCHEMATICS

MODELS: LT-3280D/LT-3780D
Page 4

MODELS: LT-3280D/LT-3780D
Page 5
PRODUCT SAFETY NOTICE
Manyelectrical and mechanicalparts in televisionreceivers have specialsafety related characteristics. Thesecharacter-
istics are often not evident from visual inspection nor can the protection afforded by them necessarily be obtained by
usingreplacement components rated for highervoltage, wattage, etc.
Replacementparts 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
receiverchassis.
WARNING:
1. Operationof this receiveroutsidethecabinet or with the cover removed presentsashock hazard
fromthe receiver's power supplies. Workon the receiver shouldnot be attempted byanyone who is
notthoroughlyfamiliarwiththeprecautions necessary when working on high voltage equipment.
2. Donot install, removeorhandlethe LCD panel in any manner unless shatterproofgogglesare
worn.People not soequipped should bekept away whilethe panel isbeing handled. Keep
thepanelawayfrom the body while handling.
3. Whenservice is required,observethe original lead dress. Where ashort-circuithas occurred, replace
thosecomponentsthatindicateevidenceof overheating.
Leakage current check
Beforereturning the receiver tothe customer, leakage current shouldbe measured using followingmethods.
1. Cold Check
Withthe alternating current (AC) plug removed from theAC source, place a jumper across the twoAC plug prongs.
Connect one lead of an ohm meter to theAC plug and touch the other lead to each exposed metal part (i.e. anten-
nas, 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 1Meg Ohm.Any resistance below this value indicates an abnormal condition
andrequirescorrectiveaction.
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 devicesofthe receiver in their operatingpositions,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
switchingdevices of the receiver intheiroperating positions, measure the leakagecurrentfor 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).

Page 6
MODELS: LT-3280D/LT-3780D

MODELS: LT-3280D/LT-3780D
Page 7
DISASSEMBLY& PANEL REPLACEMENT PROCEDURE
AV1-COVER
AV2-COVER DTV-COVER
STAND-FRAME-COVER
2. PLACESETFACE DOWNONASOFTCUSHION, WITHTHESTAND HANGING OVERTHE
EDGE OF THE TABLE.
3. REMOVESTAND-KIT.
S20：SCREW PH+SW+W
M6*21.5
1. REMOVEAV1, AV2, DTV & STAND COVERS.

Page 8
MODELS: LT-3280D/LT-3780D
4. REMOVE BACK COVER KIT.
S5：SCREW BH 4*16TP-P
F07:CABLE-CLAMP
S14
S5 S5S5 S5
S5
S5
S5
S5 S5 S5 S5
S5
S5
S5
S14
S10：SCREW IH M4*8
SCERW WITH CABLE-CLAMP
2 POINTS
14 PCS
S14：SCREW FPH M3*8
SCREW WITH STAY-STAND
S3：SCREW BH M4*10
S3：SCREW BH M4*10

MODELS: LT-3280D/LT-3780D
Page 9
5. REMOVE WALLMOUNT BRACKET
6. REMOVESHIELD-POWER-SUB &SHIELD-CASEMAIN.
SHIELD-CASE-MAIN
SHIELD-POWER-SUB
S9：SCREW PHW M3*6
S9：SCREW PHW M3*6
S16：SCREW BH+SW M6*12
S9：SCREW PHW M3*6
REMOVE WALL-MOUNT-BKT,
WHILE DEPRESSING THE HANGING
PART OF POWER-BKT BELOW.
LT-3280D
S8：SCREW BH 4*12TP-P
LT-3780D
S5：SCREW BH 4*16TP-P

Page 10
MODELS: LT-3280D/LT-3780D
7A. (LT-3280D)
(NOTNECESSARYFOR PANELREPLACEMENT)
REMOVE:
a.PLATE-MAIN-SIDE
b.SERVICE-KIT
c.PLATE-MAIN-BOTTOM
d.PLATE-POWER-BOTTOM
S11：SCREW IH M3*6
S15：SCREW_HH+SW
_UNC4#-40*7_H5
PLATE-MAIN-SIDE
PLATE-POWER-BOTTOM
SERVICE-KIT
(SA-PWB-SERVICE)
PLATE-MAIN-BOTTOM
PLATE-POWER-BOTTOM
S9：SCREW PHW M3*6

MODELS: LT-3280D/LT-3780D
Page 11
S11：SCREW IH M3*6
S15：SCREW_HH+SW
_UNC4#-40*7_H5
PLATE-MAIN-SIDE
7B. (LT-3780D) REMOVE:
a.PLATE-MAIN-SIDE
b.SERVICE-KIT
c.PLATE-MAIN-BOTTOM
d. (NOTNECESSARY FOR
PANEL REPLACEMENT)
PLATE-POWER-BOTTOM
PLATE-POWER-BOTTOM
SERVICE-KIT
(SA-PWB-SERVICE)
PLATE-MAIN-BOTTOM
PLATE-POWER-BOTTOM
NOT NECESSARY FOR PANEL REPLACEMENT
S9：SCREW PHW M3*6

Page 12
MODELS: LT-3280D/LT-3780D
8. (LT-3780DONLY)REMOVE SHIELD-INVERTER
S9：SCREW PHW M3*6
ITEM 144: AL-TAPE
It sticks on the position of a figure.
S5：SCREW BH 4*16TP-P

MODELS: LT-3280D/LT-3780D
Page 13
S6：SCREW BH 3*12 TP-P
9. REMOVEFUNCTION-KEY-KIT
S4：SCREW BH 3*8 TP-P
10. REMOVEIR-KIT
S4：SCREW BH 3*8 TP-P
11. REMOVE SA-PWB-LED

Page 14
MODELS: LT-3280D/LT-3780D
12. REMOVE POWER-KIT & SPEAKER CONNECTOR
S4：SCREW BH 3*8 TP-P
SPEAKER-CONNECTER
POWER-KIT
13A. (LT-3280D)
(NOTNECESSARYFOR PANELREPLACEMENT)
REMOVE:
a.A-PWB-MAIN 2
b. SA-PWB-POWER
c.A-PWB-POWER-SUB2
13 PCS 8 PCS
5 PCS
A-PWB-MAIN_2 SA-PWB-POWER A-PWB-POWER-SUB2
S17：SCREW PH+SW+TW M3*6

MODELS: LT-3280D/LT-3780D
Page 15
13B. (LT-3780D)
REMOVE:
a.A-PWB-MAIN 2
b. SA-PWB-POWER (NOT NECESSARY FOR PANEL REPLACEMENT)
c.A-PWB-POWER-SUB2
S17：SCREW PH+SW+TW M3*6
A-PWB-MAIN_1 13 PCS
SA-PWB-POWER
NOT NECESSARY FOR PANEL
REPLACEMENT
8 PCS
A-PWB-POWER-SUB1
7 PCS

Page 16
MODELS: LT-3280D/LT-3780D
14. (LT-3780D) REMOVE PANEL_BKT
S2：SCREW BH M4*5.5
ATTACHAL-TAPE
S5：SCREW BH 4*16TP-P
S5：SCREW BH 4*16TP-P
144 143
S2：SCREW BH M4*5.5
REMOVE CNF1/CNF2/CN1/CN2-LEAD
to the panel side not to be caught
by PANEL-BKT.

MODELS: LT-3280D/LT-3780D
Page 17
S8：SCREW BH 4*12TP-P
Screw with GND-Wire
(90mm).
Screw with GND-Wire
(50mm).
15A. (LT-3280D) REMOVE FRONT-KIT & SPEAKER
CAUTION:
UP AND DOWN DIRECTION OF PANEL IS AGAINST
LABEL AND ARROW MARK OF PANEL.
S5：SCREW BH 4*16TP-P
15B. (LT-3780D) REMOVE FRONT-KIT & SPEAKER

Page 18
MODELS: LT-3280D/LT-3780D
S1：SCREW PH M4*12
16. (LT-3280D) REMOVE PANEL_BKT
Top & Bottom is same.
4 PCS (2x2)
S2：SCREW BH M4*5.5
REMOVE CNF1/CN1/CN2-LEAD first and push in under PANEL-BKT for easy removal.
CAUTION:
UP AND DOWN DIRECTION OF
PANEL IS AGAINST LABEL AND
ARROW MARK OF PANEL.
17. (LT-3280D)
FOR RE-ASSEMBLYAFTER PANEL REPLACEMENT,
REVERSE THE DISASSEMBLY PROCEDURE.
CONTINUEFOR LT-3780DPANELREPLACEMENTAND
FURTHERDISASSEMBLYINSTRUCTIONS.

MODELS: LT-3280D/LT-3780D
Page 19
18. (LT-3780D)REMOVE SUPPORT-PANEL-BKT-RIGHT,LEFT, TOP,BOT-
TOM
Left & Right is same.
Bottom & Top is same.
S2：SCREW BH M4*5.5
S2：SCREW BH M4*5.5

Page 20
MODELS: LT-3280D/LT-3780D
70
140
40
ITEM 144:Alumi-ta
p
e 20X
45, 1Q'ty
ITEM 132:Insulating-
tape10X70
The electrode of a
connector is insulated.
ITEM 145: Alumi-tape
40X140, 1Q'ty Shield
with CNF1,CNF2.
ITEM 141: Alumi-tape :20X250, 1Q'ty
Drive-unit and Panel-outer should be grounded.
250
250
140
141
ITEM 141: AL-TAPE
20X250 1Q'ty
ITEM 142: AL-TAPE 20X140, 2Q'ty
19.(LT-3780D)ATTACHAL-TAPEAT DRIVE-UNITOF PANEL
20. (LT-3780D)
FOR RE-ASSEMBLYAFTER PANEL REPLACEMENT,
REVERSE THE DISASSEMBLY PROCEDURE.
CONTINUEFORFURTHERDISASSEMBLYINSTRUCTIONS
FOR BOTH LT-3280D & LT-3780D.