Sharp LC-20B2EA User manual

1
LC-20B2EA
SERVICE MANUAL
In the interests of user-safety (Required by safety regulations in some countries) the set should be restored
to its original condition and only parts identical to those specified should be used.
MODEL LC-20B2EA
CONTENTS
»IMPORTANT SERVICE SAFETY
PRECAUTION.................................................... 2
»SPECIFICATIONS ............................................. 3
»OPERATION MANUAL ...................................... 4
»DIMENSIONS .................................................... 5
»REMOVING OF MAJOR PARTS ....................... 6
»ADJUSTING PROCEDURE OF
EACH SECTION ................................................ 9
»TROUBLE SHOOTING TABLE ........................ 12
»CHASSIS LAYOUT .......................................... 18
»BLOCK DIAGRAM ........................................... 20
»OVERALL SCHEMATIC DIAGRAM................. 22
»DESCRIPTION OF SCHEMATIC DIAGRAM .. 24
»SCHEMATIC DIAGRAM
ËR/C RECEIVER and OPERATION Unit..... 25
ËMAIN Unit .................................................. 26
Page Page
ËTERMINAL Unit ......................................... 38
ËINVERTER-A Unit...................................... 46
ËINVERTER-B Unit...................................... 47
»PRINTED WIRING BOARD ASSEMBLIES ..... 48
»PARTS LIST
ËELECTRICAL PARTS ................................ 52
ËMAIN UNIT ................................................ 52
ËTERMINAL UNIT ....................................... 56
ËR/C RECEIVER UNIT................................ 60
ËOPERATION UNIT..................................... 61
ËINVERTER-A UNIT.................................... 61
ËINVERTER-B UNIT.................................... 61
ËCABINET PARTS LOCATION.................... 62
ËACCESSORIES PARTS ............................ 62
ËPACKING PARTS....................................... 62
ËCABINET AND MECHANICAL PARTS ..... 63
»PACKING OF THE SET ................................... 65
SHARP CORPORATION
LCD COLOURTELEVISION
S42I4LC20B2EA

2
LC-20B2EA
Specifications
CAUTION: FOR CONTINUED
PROTECTION AGAINST A RISK OF
FIRE REPLACE ONLY WITH SAME
TYPE FUSE. F3701 (2.0A, 125V),
F3702 (1.6A, 125V), F6700 (1.0A,
125V), F6701 (1.0A, 125V), F6702
(1.0A, 125V), F6703 (1.0A, 125V) ,
F6704 (1.0A, 125V)
12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212
1
234567890123456789012345678901212345678901234567890123456789012123456789012345678901234567890121
2
12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212
12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212
1
234567890123456789012345678901212345678901234567890123456789012123456789012345678901234567890121
2
12345678901234567890123456789012123456789012345678901234567890121234567890123456789012345678901212
SAFETY NOTICE
Many electrical and mechanical parts in LCD television
have special safety-related characteristics.
These characteristics are often not evident from visual
inspection, nor can protection afforded by them be
necessarily increased by using replacement components
rated for higher voltage, wattage and etc.
Replacement parts which have these special safety
characteristics are identified in this manual; electrical
components having such features are identified by “ å”
IMPORTANT SERVICE SAFETY PRECAUTION
ËService work should be perfomed only by qualified service technicians who are thor-
oughly familiar with all safety checks and the servicing guidelines which follow:
and shaded areas in the Replacement Parts Lists and
Schematic Diagrams .
For continued protection, replacement parts must be
identical to those used in the original circuit.
The use of a substitute replacement parts which do not
have the same safety characteristics as the factory
recommended replacement parts shown in this service
manual, may create shock, fire or other hazards.
WARNING
1. For continued safety, no modification of any circuit
should be attempted.
2. Disconnect AC power before servicing.
BEFORE RETURNINGTHE RECEIVER
(Fire & Shock Hazard)
Before returning the receiver to the user, perform
the following safety checks:
1. Inspect all lead dress to make certain that leads are
not pinched, and check that hardware is not lodged
between the chassis and other metal parts in the
receiver.
2. Inspect all protective devices such as non-metallic
control knobs, insulation materials, cabinet backs,
adjustment and compartment covers or shields,
isolation resistor-capacitor networks, mechanical
insulators and etc.
3. To be sure that no shock hazard exists, check for
leakage current in the following manner.
•Plug the AC cord directly into a 110~240 volt AC outlet,
and connect the DC power cable into the receiver's
DC jack. (Do not use an isolation transformer for this
test).
•Usingtwoclipleads,connecta50k ohm,10wattresistor
paralleled by a 0.15µF capacitor in series with all
exposedmetal cabinet partsandaknownearthground,
suchas electrical conduitorelectrical groundconnected
to an earth ground.
•Use an AC voltmeter having with 5000 ohm per volt, or
higher, sensitivity or measure the AC voltage drop
across the resisor.
•Connect the resistor connection to all exposed metal
parts having a return to the chassis (antenna, metal
cabinet, screw heads, knobs and control shafts,
escutcheon and etc.) and measure the AC voltage drop
across the resistor.
All checks must be repeated with the AC cord plug
connection reversed. (If necessary, a nonpolarized
adaptor plug must be used only for the purpose of
completing these checks.)
Any reading of 0.75V peak (this corresponds to 0.5
milliamp.peak AC.) or more is excessive and indicates
a potential shock hazard which must be corrected
before returning the monitor to the owner.
TO EXPOSED
METAL PARTS CONNECT TO KNOWN EARTH
GROUND
DVM
AC SCALE
50k ohm
10W
0.15 µF
TEST PROBE
A V

3
LC-20B2EA

-
SPECIFICATIONS

4
LC-20B2EA
CH
MENU
TV/VIDEO
Volume ( )/(+) CH ( )/( )
MENU TV/VIDEO (MAIN POWER)
Speaker
POWER/STANDBY indicator
A green indicator lights when the power is on and a red indicator lights when in the standby mode (the indicator will not light when the main power is off).
Speaker
Remote sensor window
(The actual location is not visible.)
Remote sensor indicator
A red indicator blinks when the TV set receives the remote control signal.
Upper control panel
To change the vertical angle of the LCD TV set, tilt the screen up to 10 degrees forward or 20 degrees backward. The TV set can also be rotated 90 degrees horizontally. Please adjust the angle so that the TV set can be watched most comfortably.
Note:
)/( ), and Volume ( )/(+) on the main unit have the same functions as the same buttons on the
remote control. Fundamentally, this operation manual provides a description based on operation using the remote control.
-
TV/VIDEO, CH( -
L
R
AUDIO OUT
AV-IN 1
RGB
AV-IN 2
S-VIDEO
VIDEO
L
R
AUDIO
POWER
INPUT
DC13V
L
R
AUDIOOU T
AV-IN1
RGB
AV-IN2
S-VIDEO
VIDEO
L
R
AUDIO
POWER
INPUT
DC13V
Carrying handle
POWER INPUT DC13V
AV-IN 1
(21pin Euro-SCART)
S-VIDEO
VIDEO
AUDIO (L)
AUDIO (R)
AV-IN 2
Antenna
AUDIO OUT (L) AUDIO OUT (R) Headphones
Rear view Remote Control
E
T
CH
TV/VIDEO
TEXT
REVEAL
HOLD
END
M
MENUSOUND
SUBTITLE
OK
(Power)
OK, Programme Table
SUBTITLE
Displays the Teletext
Subtitle directly.
HOLD
Temporarily holds
the current Teletext page.
Mute
Yellow, Timer function Menu
Green, Sound Menu
Cyan, Status Display Turns on the status display when the menu is not displayed. TV/VIDEO Channel Select MENU
Volume (+)/(-)
Flashback
Returns to the
previous channel.
Red, Picture Menu
Upwards/Downwards Selection, zoom display function (Teletext mode)
END TEXT
SOUND
Switches the
sound mode.
REVEAL Displays hidden information such as solutions to riddles and puzzles.
Right/Left Selection CH ( )/( ) Displays previous/ next page (Teletext mode)
OPERATION MANUAL

5
LC-20B2EA
DIMENSIONS
Unit: mm
CH
66.6
72.6
379
MENU TV/VIDEO
188193.5
92 381.5
473.5
1
298.8
401.3
630
107.3
72.6
163.9
229.4 65.5
30.5
468.8
1
L
R
AV-IN 1
RGB
AV-IN 2
S-VIDEO
VIDEO
L
R
AUDIO
POWER
INPUT
DC13V
100
100
1.5
AUDIO OUT

6
LC-20B2EA
REMOVING OF MAJOR PARTS
1. Remove the two back covers.
2. Remove the table stand fixing screws (4 pcs.).
3. Remove the cabinet B fixing screws (14 pcs.) and detach the cabinet.
(3: XBBSF30P06000, 3: XEBSF40P16000)
4. Remove the reinforcement angle fixing screws (4 pcs.).
5. Detach the connector from each PWB.
Cabinet B
Table stand
Back cover
Back cover
1
1
2
3
3
3
3
3
3
3
3
Terminal PWB
Inverter-A
PWB
Inverter-B PWB
Main PWB
R/C Receiver PWB
Operation PWB
4
Reinforcement angle
5
5
5
5
5
5
5555
5
5
5
5
5
5
555
5
5
5

7
LC-20B2EA
6. Remove the main PWB fixing screws (3 pcs.).
7. Remove the inverter-A PWB fixing screws (2 pcs.).
8. Remove the inverter-B PWB fixing screws (1 pc.).
9. Remove the chassis Frame-A fixing screws (3 pcs.).
10. Undo the hooks and slide the chassis frame B out of position.Take out the terminal PWB.
11. Remove the R/C receiver PWB fixing screws (2 pcs.).
12. Remove the operation PWB fixing screws (2pcs.).
13. Remove the 21-pin terminal fixing screw (2 pcs.).
69
9
7
8
13
Inverter-A
PWB
Main PWB
Chassis Frame-A
Chassis Frame-B
Terminal
PWB
Inverter-B
PWB
Operation PWB
12
11
10
R/C Receiver PWB

8
LC-20B2EA
Lamp Holder
Lamp Holder
LCD Display Unit
Prism Sheet
D-BEFM Sheet
ITO Sheet
Reflection Sheet
15
14
Diffusion Plate Cover
LCD Display Unit
(Front)
13
13
15
Shielding Plate
Reflection Plate
Lamp Set-A
Lamp Set-B
»Precautions in handling the LCD panels
1. Work in a clean room (with humidities below 50%).
2. Be sure to wear an anti-static armband.
3. Handle the panels on an electroconductive mat.
4. Be careful not to fall, shake and shock the panels.
13.Remove the four screws and open the LCD display unit.
14.Detach the D-BEFM sheet, prism sheet, reflection sheet, ITO sheet and diffusion plate Cover.
15.Remove the Lanp-holder fixing screws (6 pcs.).

9
LC-20B2EA

10
LC-20B2EA
4.Initialization
When the microprocessor (IC2001) or the EEPROM (IC2004) has been replaced or when the EEPROM has been
initialized, readjust the each adjustments.
4-1. Connect the pins (81) and (82) of IC2001 (microprocessor) to GND, and turn on the power.
4-2. Select the model name to (C2EA).
4-3. Select the inch size (20).
4-4. LED changes green from red after setting finish and about 15 seconds, initialization is completed, and it
becomes adjustment mode.
5.Adjustment
5-1. +B adjustment...Page 1 +B-ADJ
Adjust the voltage of the pin (13) of P2002 to 5.00 ±0.02V.
Note: Since 5.0V is a reference voltage of all power voltage, adjust it precisely.
5-2. Counter-bias adjustment
Vary the "COM BIAS" setting on Page 2 of the adjustment process mode so that the contrast be sharpest
(black looks most sinking).
5-3.TAMP adjustment
1) Receive the upper left of 75% white half colour bar signal.
2) See if the “Y” reading on page 2 of the adjusment process mode is somewhere following. If not, make the
“PAL TAMP” adjustment to get the “Y” reading in the range of BF thru C9.
3) If the adjustment of “PAL TAMP” is executed, write its adjustment value to the “SECAM TAMP” manually.
(Screen of the page 2 of the adjustment processing menu OSD)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
2COM B I AS 210
PAL TAMP 27
SECAM TAMP 27
GCU TOF F
RCUTOF F 0
–5
BCUTOF F
G3 B3 R3 00 00 00
–1
G1 B4 Y 0 0 00 BE
TAMP H
TAMP L
CA
BB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
Y Data
(White 75%)
5-4.White balance adjustment
Adjust “RCUTOFF” and “BCUTOFF” on the page 2 of the adjustment processing so as to obtain the colour
of the same level as the standard set.
Note: For the adjustment processing of “RCUTOFF” and “BCUTOFF”, adjust them in the indication value
range of ...–9, –7, ... –1, +1, ... +7, +9.
When it becomes even-numbered value, side favor noise sometimes occurs in the monochrome signal of
the specific gradation.

11
LC-20B2EA
6. Factory Setting
6-1. Perform a factory setting after completing all adjustments.
6-2. A “POWER” keys is made on with pushing an “TV/VIDEO” and “MENU” keys at the same time.
6-3. “K” of the inspection process mode is displayed on the screen upper left.
6-4. CH () and VOL (+) keys are pushed about 2 seconds at the same time.
6-5. Release keys, if “E” is displayed on the screen upper left and “COMPLETE” is displayed on the bottom of it.
6-6. After a while, a power will be in a standby mode and a setup will be finished.
Note:“First installation” serves on “Deutsch”.
7. Lamp error detection
7-1. Functional description
This LCD colour television has a function (lamp error detection) to be turned OFF automatically for safety
when the lamp or lamp circuit is abnormal.
If the lamp or lamp circuit is abnormal, or some other errors happen, and the lamp error detection is executed,
the followings occur.

The main unit of television is turned OFF 5 seconds after it is turned ON.(The power LED on the front side
of TV turns from green to red.)
If the situation 
happens 5 times sequentially, television can not be turned ON.(The power LED remains
red.)
7-2. Countermeasures
7-2-1.Check when turning OFF the lamp error detection
When television is turned OFF by the lamp error detection mentioned above, it enters the adjustment
process with the power LED red.Entering the adjustment process turns OFF the error detection and turns
ON TV.
This enables the operation check to detect errors in the lamp or lamp circuit.
Check whether "ERROR NO RESET" on line 9, page 1 of the adjustment process is 1 or more. If it is 1 or
more, it indicates the lamp error detection was executed.
7-2-2.Resetting of the lamp error count
After confirming that the lamp or lamp circuit is normal, reset the lamp error count. Select "ERROR NO
RESET" on line 9, page 1 of the adjustment process and set the number to 0 using the volume button.
1 + B– A D J 160
M O D E L C2EA
V E R 1 . 2 0
Reset 0
Afterwards, perform the operation check to confirm that the lamp error detection does not function.
Page 1 of the adjustment process
INCH SIZE 20
NTSC PWM FREQ 0C0
PAL PWM FREQ 0BD
NTSC PWM DUTY 0
PAL PWM DUTY 0
T V GAIN OFF
ERROR N O RESET 5
PUBLIC MODE OFF
C2EA

12
LC-20B2EA
TROUBLE SHOOTINGTABLE
~
~~~

13
LC-20B2EA
TROUBLE SHOOTINGTABLE (Continued)
No picture
(1/3)
No picture at all No TV and S-VIDEO output No TV output No VIDEO2 output
Check all the settings microprocessor's adjust process menu.
Is in/output of Check IC801 Is in/output of Check IC402 Is voltages at Check their Check V1.IN line IC801 normal?
No
and its IC402 normal?
No
and its pins 6,7,18 of
No
power lines.
No
and its
Yes Yes Yes
Yes
Yes
Yes
Yes
tuner normal?
Is in/output of Check IC1201 Is input at pin Check IC801, Is output at pin Check tuner IC1201 normal?
No
and its 73 of IC801
No
AV1 line and 13 of tuner
3 of tuner
No
and its
perip
h
eralparts.
perip
h
eralparts. perip
h
eralparts.
perip
h
eralparts.
perip
h
eral
parts.
normal? t
h
eir
Check LCD Is input at pin Check its line. pane
l
vo
l
tages
an
d
waveform.
Is the pins 2 Check IC402 and 4 of IC402
No No
No
and its
at "H" and "L" peripheral parts.
state?
Is the pins 65 Check its lines.
normal?
normal?
and 66 of IC2001 at "H" and "L"state?
Is input at pin 75 of IC801 normal? perip
h
eralparts.

14
LC-20B2EA
TROUBLE SHOOTINGTABLE (Continued)
No picture
(2/3)
No S-VIDEO output No VIDEO1 output No TELETEXT output
Check all the settings microprocessor's adjust process menu.
Is input at pin
Check SY-line, Is input at pin Check AV2 Is input at pins CheckIC1203
1 of IC402 and
No
SC-line
and
their 74 of IC801
No
line and its 2,5,11,14 of
Yes
and its
pin 71 of IC801
peripheral parts. normal? peripheral parts. peripheral parts.
peripheral parts. peripheral parts.
IC1203 normal?
Is output at pins Check 3~5 of
Yes
connection
SC1602 normal?
cable.
Is output at pins Is output at pins Is input at pin Check IC1601 1 and 7 of
Yes
Yes
57~59 of
No
No
No
No
No
21 of IC1601
Yes
and its
IC1619 and pin IC1601 normal? normal? peripheral parts. normal?
Check IC1619, IC1690 and their Check the Check V2VO
line and its
normal?
1 of IC 1620
R,G,B line.

15
LC-20B2EA
TROUBLE SHOOTINGTABLE (Continued)
No picture
(3/3)
Colour is unusual No picture image inversion Gradation defect
Check all the settings microprocessor's adjust process menu.
Is output of Check R1202 Is in/output of Check R1209 Is output V0,V7,
V17,V21,V32, V64,V122,V176, V235,and V255 normal?
Check IC1106~ IC1108, IC1114 IC1115 and their
R0~R7
No
and its SPIO and
No No
and its
normal? normal? normal?
peripheral parts. peripheral parts.
peripheral parts.
peripheral parts.
peripheral parts.
peripheral parts.
SPIO normal?
Yes
Y
es
Is output of Is output of Check R1204 Is output of U/D Check IC1206 G0~G7
Yes
B0~B7
No
No
and its normal?
No
IC1207,Q1201
and their
Check R1203 and its

16
LC-20B2EA
TROUBLE SHOOTINGTABLE (Continued)
No sound
(1/2)
No sound from front speakers No sound from headphone No sound fromoutput line
Check all the settings microprocessor's adjust process menu.
Is the pin 53 of IC2001 Muting effect is on. Is the pin 52 of IC2001 Muting effect is on. Is output at pins 33 Check IC1901 and its
in the "L" state?
No
Check the FSMUTE in the "L" state?
No
Check the HP_MUTE and 34 of IC1901
No
peripheral parts.
Yes
Yes
Yes
Yes
l
ine.
l
ine. normal?
Ye
s
Is output at pins 27 and Check IC1901 and its Is output at pins 24 and Check IC1901 and its
Is output at pins 1 and Check IC3500 and its
28 of IC1901 normal?
No
peripheral parts. 25 of IC1901 normal?
No
peripheral parts. 7 of IC3500 normal?
No
peripheral parts.
Yes
Yes
Is output at pins 1 and Check IC1903 and its Is output at pins1 and Check IC304 and its 7 of IC1903 normal?
No
peripheral parts. 7 of IC304 normal?
No
peripheral parts.
Ye
s
Is output at pins 8 and Check IC3305 and its Check headphone jack 12 of IC3305 normal?
No
peripheral parts. and connection cable.
Check front speakers and connection cable.

17
LC-20B2EA
No sound
(2/2)
No sound from SCART SCART sound failure TV sound failure
Check all the settings microprocessor's adjust process menu.
Is output at pins 36 and Check IC1901 and its Is input at pins
53 and
Check theire lines and Is output at pin 11 Check the tuner and
37 of IC1901 normal?
No
peripheral parts. 54 of IC1901 normal?
No
theire peripheral parts. of tuner normal?
No
its peripheral parts.
Ye
s
Ye
s
Ye
s
Is output at pins 1 and Check IC1902 and its Is output at pins
27 and
Check IC1901 and its Is input at pins 67 and Check IC1901 and its
7 of IC1902 normal?
No
peripheral parts. 28 of IC1901 normal?
No
peripheral parts. 69 of IC1901 normal?
No
peripheral parts.
TROUBLE SHOOTINGTABLE (Continued)

18
87109654321
A
B
C
D
E
F
G
H
LC-20B2EA
CHASSIS LAYOUT
MAIN Unit
TERMINAL Unit

19
1716 1918151413121110
LC-20B2EA
INVERTER-A Unit
INVERTER-B Unit
R/C RECEIVER Unit
OPERATION Unit

1234567891011 12 13 14 15 16 17 18 19 20
A
B
C
D
E
F
G
H
I
J
LC-20B2EA LC-20B2EA
20~21
BLOCK DIAGRAMS
1234567891011 12 13 14 15 16 17 18 19 20
A
B
C
D
E
F
G
H
I
J