SERVICE MANUAL Colour Television
FILE NO.
Model No.PC-R20R2
(USA)
Service Ref.No.PC-R20R2-00
SPECIFICATIONS
Receiving System
Colour System
Picture Tube
Ext. Antenna
Ext. In/Out
Speaker
Audio Output
Power Consumption
Dimension
Net Weight
REMOTE CONTROL
Transmitting System
Power Supply
Dimension
Net Weight
Design and specifications are subject to change without prior notice.
: M
NTSC
:
: 20 inch screen
: 75 Ohm Coaxial Cable
Audio/Video -In/Out
:
: (8 Ohm) x 2
: Maximum 3W
: AC 120V 60Hz, 84W
: 525(W) x 510(D) x 464(H)mm/
20.7(W)
: 22.8 kg/50.26lbs
: Infrared
: DC 3V (1.5 x 2)
: 60(W) x 200(L) x 24(D)mm/
2.4
: 100 g(approx)/0.22lbs
x20.1(D) x 18.3(H)inch
(W) x 7.9(L) x 0.9(D)inch
Product Code: 1 113 495 46
Original Version
Chassis Series: 3Y03
Give complete SERVICE REF.NO. for
parts order or servicing. It is shown on
the rating plate at the cabinet back of
the unit.
This T.V. Receiver will not work properly in
foreign countries where the television
transmission system and power source
differ from the design specifications.
Refer to the Specification table.
""
REFERENCE NO. SM 2300011
Contents
Safety Notice..................................................................2
Chassis Block Diagram....................................................3
IC Block Diagram .........................................................4-7
PCB Top Layer .............................................................8-9
Service Adjustments .................................................10-16
Purity and Convergence Adjustment ...............................17
Control Location............................................................18
Input and Output Terminals.............................................19
Operation Instructions...............................................20-21
Mechanical Disassemblies .............................................22
Cabinet Parts List ..........................................................23
Circuit Diagram..............................................................24
Chassis Electrical Parts List.......................................25-33
Safety Notice
SAFETY PRECAUTIONS
1:An isolation transformer should be connected in the power line between the receiver and
the AC line when a service is performed on the primary of the converter transformer of the
set.
2:Comply with all caution and safety-related notes provided on the cabinet back, inside the
cabinet, on the chassis or the picture tube.
3:When replacing a chassis in the cabinet, always be certain that all the protective devices
are installed properly,such as,control knobs, adjustment covers or shields, barriers,isola tion resistor-capacitor networks etc.. Before returning any television to the customer,the
service technician must be sure that it is completely safe to operate without danger of
electrical shock.
X-RADIATION PRECAUTION
The primary source of X-RADIATION in television receiver is the picture tube. The picture
tube is specially constructed to limit X-RADIATION emissions. For continued X-RADIATION
protection, the replacement tube must be the same type as the original including suffix
letter. Excessive high voltage may produce potentially hazardous X-RADIATION. To avoid
such hazards, the high voltage must be maintained within specified limit. Refer to this
service manual, high voltage adjustment for specific high voltage limit. If high voltage exceeds specfied limits, take necessary corrective action. Carefully follow the instructions for
+B1 volt power supply adjustment, and high voltage check to maintain the high voltage
within the specified limits.
PRODUCT SAFETY NOTICE
Product safety should be considered when a component replacement is made in any area
of a receiver. Components indicated by mark in the parts list and the schematic diagram
designate components in which safety can be of special significance. It is particularly
recommended that only parts designated on the parts list in this manual be used for component replacement designated by mark . No deviations fromresistance wattage or voltage ratings may be made for replacement items designated by mark .
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IC Block Diagram
IC 001 (MULTI SYSTEM COLOR TV CPU) LC863224A
-4-
IC Block Diagram
IC 201 (IIC BUS SINGLE CHIP VIF,SIF,VIDEO CHROMA) LA76814K
7.5K
IN
FBP
V/C
VCC
10K
330p
REF
4.7K
MetalFilm(1%)
1K
1K
HOR
GND
10K
1u
1000p
24K
24K
0.47u
0.01u
16p
10u
SVO
V/C
GND
1u
[Y-IN ]
EXT-V IN
EXT-AUDIO
0.01u
47u
[S-C IN]
INT-V IN
15uH
1K
VCO
1000p
IN
10p
1u
680K
330
2.2u
1K
0.47u
COIL
0.47u
330
10u
3K
0.01
1000p
FBP
C/D
VCO
29 28
32 31 30
XRAY
36 35 34 33
APC1
VCO
39 38
40 37
43 42 41
44
CLAMP CLAMP
46 45
48 47
50
52 51 49
53
54
HOR
ACC
KILLER
TINT
BPF
(ON/OFF)
SW
SW
VIDEO
AFT
A2C PLL
AMP
VIDEO
SPLL
BPF
BPF
HOR
1/256
COLOR
CLAMP
DEMO
SYNC
TRAP
TRAP
LIM
AMP
BRIGHT
CONTRAST
BLACK
SEP
PEAKING
DELAYLINE
DET
VIDEO
AFC2
PHASE
AFC1
VER
RGB
STRETCH
CORING
FM
DET
VER
SEP
OSD
MATRIX
OSD
CONTRAST
VIF
IF
AGC
SW
HOR
OUT
SHIFTER
Vcc
HOR
C/D
VER
RAMP
SW
DRIVE/CUTOFF
BRIGHT
CLAMP
ABL
BUS
5V
IF Vcc
RF
AGC
DC
VOL
OUT
HOR
1u
3K
0.01u
10u
56p
100
Vcc
0.01u
10u
0.1u( )
0.1u( )
0.1u( )
1K
1K
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
100K
0.01u
5 6 7 8 9
0.01u
0.022u( )
0.01u( )
1 2 3 4
VC
AUDIO
0.015u
150
0.33u( ) 0.33u( )
VER
5.6k
B
G
R
100
100
0.1u
100K
1u
100
SAW
FILTER
30K
OUTP
150
OUT
OUT
OUT
OUT
IF
HOR
VCC(9V)
Out
Sync
VCC
(9 12V)
IN
FB
B
IN
G
IN
R
IN
LA76814K BLOCK DIAGRAM
ABL
BUS
CLOCK
BUS
DATA
AF
VCC
IF IN
RF
-5-
IC Block Diagram
IC301<Vertical Output> LA7840
THERMAL
PROTECTION
PUMP
UP
-
AMP
+
1
2
GND
Ver.OUTPUT
IC 403(3W AUDIO OUTPUT)LA 4285
3
OUTPUT STAGE Vcc
EVR
4
5
NON INV.INPUT
INVERTINO INPUT
7
6
c
c
V
PUMP UP OUT
+
-
INT
EXT
1 2 6543 1097 8
5V
++6++
++++
PRE
GND
INT/EXT
SM
EVR
CONT
-6-
D.C.
PWR
NF
PWR
GND
VCC
++
+
+
RL 8
IC Block Diagram
IC602<POWER > STR-G6653
VIN
4
1
D
START
REG.
T.S.D
O.V.P
LATCH
O.S.C
+
Comp2
Comp2
DRIVE
2
-
Vth(1)
+
Comp1
-
Vth(2)
S
5
O.C.P/F.B
3
GND
IC603<PHOTO TRANSISTOR> TLP621
TLP621
1
2
1:ANODE
2:CATHODE
3:EMITTER
4:COLLECTOT
4
3
-7-
CRT, FRONT AV&CONTROL PCB Top Layer
FRONT AV & CONTROL PCB TOP LAYER
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Service Adjustments
Please notice the following before alignment and equipment
1. Don’t short any two soldering points, which should not be shorted and don’t touch any components,
which should not be touched.
2. Please pull out plug before equipment.
3. For safety reasons, all components equipped or replaced should be identical with BOM.
4. Must be warm up for 30 minutes or more and degauss CRT thoroughly with demagnetizer before
alignment.
The data of EEPROM must be stored before the adjustment for main chassis. And EEPROM must be
corrected by the correct file “3Y03_ROM_CORRECT.hex” to avoid signal of CH6 weaken. R.bias,
G.bias, B.bias, R.drv, G.drv, B.drv should be set to proper values. Sub_bright is set to 63 usually.
Tools and equipments for adjustment
1. small “-“ screwdriver
2. screwdriver without inductance
3. Pattern Generator
4. DC Regulated power supply
5. Digital Voltmeter
6. Sweep Signal Generator
7. 20MHz 2-channel Oscilloscope
Signal condition
ITEMS LOGO
PICTURE
CARRIER
PATTER N SYSTEM
SOUND
MODE
REMARK
1 CH14 471.25 MHZ COLOR BAR NTSC/M
MONO
1KHz
2 CH3 61.25 MHz GRAY SCALE NTSC/M
BTSC
0.3k,3kHz
3 CH8 181.25 MHz MONOSCOPE NTSC/M
MONO
MUSIC
4 CH12 205.25 MHz
CROSS HATCH
NTSC/M
MONO
1KHz
Adjust for main chassis
PIF Adjustment (45.75MHz)
a. Tuner AGC connects to GND. Pattern Generator outputs 45.75MHz I.F. signal (70dbµV)and connects to SAW filter
output terminal through a capacitor .
b. Connect Digital voltmeter across C227. DC Regulated power supply positive terminal output +14V to C617.
c. Adjust L203 coil to obtain 3.6V Digital voltage meter reading.
NOTE: To cancel this adjustment , L203 can be adjusted before inserted to the chassis with a special equipment.
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Service Adjustments
B+ adjustment
a. Disconnect horizontal load. Connect a bulb (100 W) AC 250V across C321.
b. Add 220V AC 50HZ to CN601 and switch on power switch.
c. Test the voltage with digital voltage meter between C321 two terminals.
d. Adjust VR601 to obtain +110V¡À0.5V.
AGC alignment
a. Receive 60dB RF signal. Connect Digital voltmeter positive terminal to tuner AGC terminal and negative terminal
to GND.
b. Press “MENU” key, then press “Q.VIEW” key, “MUTE” key in turn on telecontroller. TV SET will go to factory mode.
Press “TIMER” key to go to the next factory menu. Go to MENU5 status by this means. Press “MENU” key to exit
factory mode.
c. Select RF.AGC by pressing “CH+” and “CH-“keys. Adjust “VOL+” and “VOL-“ keys to obtain 4V Digital voltage
meter reading.
COMPLETE MACHINE GENERAL ADJUSTMENT
Go to factory mode according to 4-2-2 before warm up line
Focus Adjustment
a. Receive monoscope pattern.
b. Set TV to work in dynamic status.
c. Adjust the focus knob of FBT to get the clearest picture.
Screen Voltage Adjustment
a. Check the R.bias, G.bias, B.bias, R.drv, G.drv, B.drv and sub_bright. Go to factory mode “MENU2” status
according to 4-2-2. Usually G.bias should be same as the value of auto white balance equipment. And
SUB_BRIGHT is 63.
b. Set Cross_BW ‘3”. Then the picture will be a white “+”. Cross_BW is in factory menu 3.
c. In menu 5, select SUBB.ADJ and set it to “1”. Adjust the screen knob of FBT to get a faintness “+”.
d. Restore the SUBB.ADJ to “0” and CROSS.BW to “0”.
White Balance Adjustment (Applied in factory)
a. Set TV AV status in custom mode(Or other mode need for the adjustment) . Receive black white pattern.
b. Insert six-row-wire into CN002.Press adjustment keys, and then go to automatic white balance adjustment.
c. PIN DISCRIPTIONN OF CN002:
1£ºSDA£¬ 2£ºSCL£¬ 3£ºGND£¬ 4£ºGND£¬ 5£ºSCL£¬ 6£ºSDA¡£
d. After adjusting well, pull out six-row-wire.
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