Xoceco TK1433, TK2026, TK2050, TK2053 Schematic

COLOR TELEVISION

TK14"-20"

CONTENTS

Safety instruction………………………………………………………………………1
General instruction……………………………… ……………………………………… .1
Alignment instruction……………………………………………………………………2
Alignment flow ..……………………………………………………………………..2
Alignment method…………………………………………………………………..3

Block diagram......………………………………………………………………………...10

MAIN IC………… …………………………………………… ………………………..11
Electrical parts list………………………………………………………………16
Exploded view…………………….……………………………………………….45
Schematic diagram………………………………………………………………….53

Note: This service manual is only for professional service personnel’s reference. Before

servicing the unit, please read the following items carefully.

1 Safety instruction

1.1 X-RAY radiation precaution

1.1.1 Excessive voltage will cause harmful X-ray. To avoid this radiation hazard, the high voltage should
fall within the limitation. The appliance works at AC 120V, 60Hz. The high voltage of zero beam
current(brightness, contrast and color is m in) should be within 27kV on condition that the main power
(B+) voltage is AC120V. And it should not exceed 28kV in any condition.
When servicing, please refer to the HIGH VOLTAGE CHECK procedure this service manual before
check the high voltage and the high volt age meter should be reliable and accurat e.
* Keep the main power voltage at 120V when checking the high voltage.

1.1.2 The primary source of X-RAY RADIATION is the CRT. The CRT of this TV set have gotten the
approval of safety authenticat ion i nspect ion. The rep lacem ent CR T should be exactly the same type and
specification CRT which has gotten a similar safety approval, and check the high voltage according to
the HIGH VOLTAGE CHECK procedure.

1.2 safety precaution
a. Since the power supply circuit of this receiver is directly connected to the AC power line, an isolation
transformer is necessary during dynamic service to avoid possible shock hazard.
b. Always discharge the graphite layer conductor when moving the CRT.
c. Disconnect the power cord before replacing parts.
d. When replacing high-power resistor, keep the resistor 10 mm away from the circuit board.

1.3 Component safety precaution
Many electrical and mechanical parts in the chassis have special safety-related characteristics. These
characteristics are often passed unnoticed by a visual inspection. Replacement parts which have these
special safety characteristics are identified in this manual and its supplement electrical components
having such features are shaded or marked by on the schematic diagram and the parts list. Before
replacing any of these components, read the parts list in this m anual carefully. The use of substitute
replacement parts which do not have the same characteristic as specified in the parts list may create
shock, fire, X-RAY RADIA TI O N or other hazards.

2.General instruction

2.1 Copy the standard model data to let EEPROM (N702 24C08)of the chassis have those data before
placing it on the unit, do “factory adjustment” if necessary. If use a blank EEPROM directly, you should
preset IIC data and then do other common adjustment. Refer to TABLE1 to preset EEPROM.

2.2 the adjustment should be done under following circumstances without additional instruction
a) Alternating current 120V/60Hz
b) Preheat at least 30 min

2.3The unit has auto degaussi ng circuit , the auto de gaussing proce ss can be finishe d within 2s w hen the
main power. only when turn on the unit at least 20min after last time turn off TV does the auto
degaussing circuit work.

2.4 If the CRT with magne tis m af fects co lor p urity and conv ergence, when the auto deg auss ing eraser. if
the color purity and convergence are still n ot very good, then corresponding adjustment should be done.
Refer to picture tube adjustment method for adjustment.

1

3 Alignment instruction

3.1 Debugging item
a)adjust mode instruction
b)B+ voltage adjustment
c)RFAG C voltage adjustment
d)focus adjustment
e)Screen-grid voltage white balance, sub brightness adjust ment
f)filed scan center , line , amplitude adjustment
g)H-scan center adjustment

3.2 Alignment flow

E2PROM copy

High voltage check

B+ adjustment

RFAGC adjustment

Focus adjustment

Screen-grid voltage white

balance

Scan amplitude

center

X-ray protect check

Filament voltage check

AV check

Sub brightness check

White balance check

Color Purity, convergence check

AV, S terminal check

check

Fig-1 alignment flow

2

The unit and remote control

CCD function check

3.3 Enter/exit factory adjustment method

Use remote control, press “MENU” button, then press 6483,”TEST”will appear on screen to show that
you have entered the factory adjust ment method, press “STANDBY” to exit it. Use factory remote contro l,
press the “PRESET” and “TEST” button, then the screen display “test” which means you have entered
into the factory adjustment mode, press the “TEST” or “STANDBY” to exit.

3.4 select adjustment item and adjust data

after entering factory adjustment mode, press 1-4 number buttons to select menu 1- menu 4; To enter
into MENU0, MENU5-MENU9, you may return to MENU1-MENU4 or just after you enter into “TEST”
interface, quickly press“CHILD LOCK” button and then the number button (0,5-9) to enter into relative
menus. Press “CH+” and “CH-” to select and “V+” and “V-”to adjust.

3.5 User purview

a).Factory adjustment mode menu1-menu4: only debugging worker, service checker, craftwork
technician, designer may operate.
b).Factory adjustment mode menu0, menu5-menu9: only craftwork technician, designer may operate.

4 Alignment method

4.1 B+ voltage adjustment

a) connect B+ point with a digital voltmeter to measure the negative pole of VD524
b) receive PHILIPS test pattern signal and set the picture to standard.
c) Adjust VR501 to let the value of B+ voltage be 110 V ±0.5 V (yongxin super pure flat)

4.2 AGC adjustment
a) receive VHF-H band,60 dB RF signal.
b) Select factory menu2 of “AGC”.
c) Adjust AGC-TOP to let the picture just without noisy, then the voltage of tuner AGC is the

required value for adjustment.

d) exit factory menu

4.3 Normal temperature aging
a) do not receive signals.
b) under ”Test” condition, set the accelerator to an appropriate point for aging.

4.4 Accelerator adjustment
a) do not receive signals;
b) select “SC” of factory menu3 to let the field scanning stop working.
c) adjust acceleration potentiometer to let bright lines just appears on screen.
d) exit SC menu.

4.5 High voltage check

Note: the main power voltage (B+=110 V)can aff ect the high voltage directly, so be sure to let the B+
power voltage accurate. Under any state, the high voltage should not exceed 28 kV.

a) connect an accurate high voltage meter between the second anode cap of picture tube and

ground.

b) turn on TV and receive testing card signal.
c) set picture to standard, the high voltage should be 25 kV± 0.5 kV.
d) the high voltage should not exceed 27KV with minimum brightness and contrast.

4.6 Focus adjustment
a) receive A12-PHILIPS (NTSC)signal

3

b) adjust focus electrode potentiometer on FBT to optimize B area focus of screen.

4.7 White balance adjustment (color temperature 12000°K± 8MPCD,X=0.270± 0.008,Y=0.283± 0.008)
a) receive full white signal, set color is 0
b) select factory menu3
c) on the basis of blue gun ”BD”, select and adjust “RD, GD” item to make white balance

2

respectively at brightness Y=6cd/m

, Y=80cd/m2 meet standard (color temperature 12000°K± 8MPCD,

x=0.270± 0.008, y=0.283± 0.008)

2,

d)If at brightness Y=6cd/m

white balance can not meet standard, you may adjust “RB, GB”item,

then repeat step C) until white balance meet standard.

4.8 Filed scanning adjustment (fig-2)
a) Receive NTSC of A12-PHI L I PS t est pattern signal.
b) select factory menu1
c) adjust V- SLO PE menu to let the horizontal center line of test pattern above blanking.
d) select V- SHI FT menu and adjust to let the vertical center of picture coincide with
vertical center of picture tube.

e) Select V-SIZE menu and adjust to let the vertical reproduction ratio of picture acceptable 8%.
f) Adjust V.SC to optimise the vertical S correction of picture.

Horizontal line

Under part banking

Fig-2 field scan adjustment

4.9 Horizontal scanning adjustment (Fig-3)

a) Receive A12-PHILIPS(NTSC) signal
b) Select factory menu1
c) Select H.SHIFT menu and adjust to let the scanning horizontal center coincide with mechanical

center of picture tube

d) Exit factory menu

Fig-3 line scan adjustment

a

4.10 Sub-brightness adjustment

a) Receive A12-PHILIPS(NTSC) signal
b) Select “SB” of factory menu3
c) Adjust “SB” to let things between the sixth and seventh grey scale clear

4.11 OSD adjustment

a) Receive A12-PHILIPS(NTSC) signal
b) Select OSD H and OSD V of factory menu4. Adjust OSD H and OSD V to let OSD at a specified

4

place.

c) Exit factory menu

4.12. Checking point

4.12.1 High voltage check

1) Connect High Voltage meter between CRT second anode and GND.

2) Receive A7 signal, set the control to “STANDARD”, measure the high voltage value, the reading

should be 25 kV±0. 5 kV

3) Set the brightness and contrast to miminum (zero beam current), measure the high voltage, the

reading should not exceed 27kV.

4.12.2 CRT filament v oltage check

Receive A7 signal, set user control to “STANDARD” mode, use effective voltage meter to measure CRT
filament voltage, the reading should be (6.3±0.3) Vrms

4.12.3 X-ray protection check

1) Receive A7 signal, set user control to “STANDARD” mode.

2) Use voltameter to me asure VD482 positive pole to GND voltage, the reading should be betw een 1.0

V~2.5 V.

3) Use 5.3V DC regulated voltage power with 1K resistor in series to touch TP1 (VD482 positive pole),

connect DC regulated v oltage power negative pole to GND, X-Ray prot ect ion circuit should function,
at this time the TV set should be without raster, without sound. Disconnect the DC regulated voltage
power , picture and sound should restore to normal.

4.12.4 Picture and sound check

1) Receive standard TV signal.

2) Use picture control buttons to check color, contrast, brightness, sharpness, tint’s function.

3) Use sound control buttons to check volume control function.

4.12.5 Sub-brightness check

Receive A7 signal, set brightness to 75, contrast to 50, color to 0, sharpness to 50, picture left side 1-6
lattices slightly light up.

4.12.6 Color purity and convergence check (in normal way)

4.12.7 AV terminals IN/OUT check, S-VIDEO in check, Y,Cb,Cr in check.

4.12.8 Other buttons on the TV set and remote cont roller function check.

4.13 Degaussing

a) The unit has and auto degauss ing circuit, the degaussing circuit works several seconds after turning

on TV

b) If you want to move TV or change the direction, turn off TV and ten minutes later the degaussing

circuit will work
c) For better degaussing effect, you can use magnetic eraser
d) Move the magnetic eraser clock wise before your TV, when it is 2m away from your TV, turn off the

magnetic eraser. If the effect is still not very good, you can adjust “color pur it y” and “convergence”

5

4.14 Color purity correction
a) Turn on your TV
b) At least 15 minutes later, use anti-magnetized coil for degaussing
c) Obtain maximum brightness and contrast
d) Select factory menu3 and adjust to let R and B be zero, then let only green raster appear on the

screen at the moment
e) Loosen screws of deflection yoke frame to let vertical green belt appear on screen only
f) Move the rubber wedge
g) Rotate along neck of picture tube and slide color-purity magnets until the green belt at the middle of

screen and is vertical at the same time
h) Slowly move the deflectio n y oke backw ard of forwar d until the w h ole gre en rast er appears on scree n,

tighten the screws of the deflection yoke
i) Check the color purity of red raster and blue raster
j) Adjust white balance again to obtain white raster

4.15 Convergence correction

4.15.1 Central convergence correction
a) Turn on your TV
b) At least 15 minutes later, receive square test pattern signal
c) Adjust brightness and contrast to get the best picture
d) Adjust the angle of two tetrode magnetic rings to let the red vertical line coincide with the blue

vertical line at middle of screen
e) Keep the angle unchanged, move the two tetrode magnetic rings at the same time to let t he red and

blue horizontal lines coincide at middle of screen
f) Adjust two hexode magnetic rings to let the green line coincide with the mixed line of red and blue.

Adjust the angle between them will affect the vertical line, move them together will affect the

horizontal line.
g) Repeat d), e), f) and observe the movement of red, green and blue.

4.15.2 Ambient convergence correction
a) Turn on your TV
b) At least 15 minutes later, loosen the screws of the deflection yoke
c) Fixate the rubber wedge temporarily under the deflection yoke
d) Move the deflection yoke upward or downward to get best convergence, push the rubber wedge into

space between picture tube and deflection yoke to fixate the deflection yoke temporarily
e) Place the rubber wedge whose overlay paper has been removed at t he bot tom space
f) Move the deflection yoke left and right to get best convergence
g) Keep the condition unchanged, place another rubber wedge whose overlay paper has been

removed also at the upper space at the same time
h) Remove the interim rubber wedge, adhere it to picture tube and deflection yoke
i) After placing three rubber wedges, check all the convergence again
j) Stick three transparent viscous belts to the rubber w edge

4.16 Software adjustment instructions

4.16.1 instructions
This software contain MTS (option), English, Frence and Spanish of OSD, CCD and Parental Control
function, FS tuner mode, 181 channel.

6

4.16.2 turn on the unit in the STANDBY state
Press CH+/CH- buttons turn on in the STANDBY state.

4.16.3 Information of software version
Enter MEU9 of the factory menu in the top.

4.16.4 “STANDARD”, “COLORFUL” and “ SOFTNESS”
a).Enter MENU5 Mode of the factory menu
b).charge their for seemly analog quantity, then return standard option.

2

Chart 1 I

2

C standard UOC for export bus control adjustment i t em def a ul t set ting

I

C TDA (NOM)8377-B-6NA E2PROM pre-set data

MI Items range Preset

M0 SUBCON 0-63 56(sub-contrast)

SUBCOL 0-63 56(sub-chroma)
SUBSHP 0-63 48(sub-acutance)
SUBTINT 0-63 31(sub-hue)
AKB ON/OFF ON

M1 V.SLOPE 0-63 36(field center adjustment)

V.SHIFT 0-63 32(field point adjustment)
V.SIZE 0-63 36(field amplitude adjustment)
V.SC 0-63 32(field line )
HSHIFT 0-63 32(line point adjustment)
PROGRAMA.NO 2(channel)

M2 AGCTAKEOVER 0-63 21(AGC adjustment)

SHIPPING 0(leave factory set)

M3 BT 0-100 75(adjust white balance of brightness)

CT 0-100 75(adjust white balance of brightness contrast )
SC 0
RB 0-63 32(red cut off level adjustment)
GB 0-63 32(green cut off level adjustment)
RD 0-63 32(red cut off level adjustment)
GD 0-63 32(green cut off level adjustment)
BD 0-63 32(blue cut off level adjustment)
SB 0-63 40(sub brightness adjustment)

M4 OSD.V.POSITION 0-63 15(OSD position)

OSD.H.POSITION 0-63 25(OSD H-position)
BTSC-MODE MONO/STEORO MONO(STEORO,SAP )
BTSC-ST 0-15 13
BTSC-SP 0-15 12
BTSC-L1 0-15 1

7

BTSC-A1 0-31 15
BTSC-A2 0-31 0
BTSC-TC 0-7 0
BTSC-STS 0-1
BTSC-ADJ

M5 MODE STANADARD(standard, soft, floweriness)

BRIGHT 0-100 75

COLOR 0-100 50
SCBRIGHT 0-63 23
YDELAYTV 0-15 12
YDELAYAV 0-15 12

M6 OSO 0-1 1(field over-scan switch)

AGCSPEED 0-3 1(AGC of speed)
FFI 0-1 0(IF PLL SPEED)
FMWS 0-1 1(frequency range of sound OFF=225KHZ,O N=45 0 KHZ)
RP0 0-3 0(pre-shock and over-shock scale)
NTSCMATRIX USA/JAPAN USA
VOLPIN 0-1 0(1:push-pull output; 0: OC gate output.)
SOFT CLIP 0-3 3(white level limit)
PEAK WHITE 0-15 15(peak white limit)
CORING 0-1 0(coring noise reduct ion)

M7 AV2 0/1 1

SVHS 0/1 1
YUV 0/1 1
VOLADJPOING 1(volume value have:1,25,50, 75)
VOLVALUE 20(volume curve value:20,60,75,90)

M8 CATHOOELEVEL 0-15 7(cathode level)

UOCVOLUME 0/1 0(0:PWM terminal control; 1:UOC sound amplitude

FMATT 0-63 45(UOC sound output of amplitude) BTSC : 38
COMBFILTRE 0-1 0(N comb filter)
HEADPHONE 0-1 0(earphone function selection)
VM OPTION 0/1 0(VM function selection)
FRANCE 0/1 1 French
SPANISH 0/1 1 Spaish

M9 NOM8377-B-6NA

STARTON 0-2 2(turn on)

CONTRAST

0-100 75

0

control of inside)

8

STARTTIME 6-15 8(turn on time)
IF OFFSET 0-63 32(IF compensate)
TUNER OPTION 0-2 0(BXATB011F---X/ BXAT B108F---K) 1 (BXATB017F---K)

2(XXX)
GAME 0/1 0
GALENDA 0/1 0

9

Block diagram

rCb

DY

S

F

S

Speaker

A101 Z301 V801

TDA8377

TUNER

AN702

KA5Q0765

T501

POWER

UNIT

video

180V
+13.5

-13V

Y

C

CRT

BOARD

CREEN

OCU

SAW

V352 N121

S

TRAP

24C08

110V

26V
12V

8V
5V

3.3V

video

bus

IF IN Y IN

RF AGC V IN

U IN
CVBSINT
CHROMA
IFVO OUT
CVBS/Y IN

SDA
SCL

AUDIO OUT IK
RGB OUT
V OUT H OUT

V IN

STV9302A

V OUT

H IN

H OUT

TT2140

T451

H OUT

video

audio

CRT

video

BU4052

audio

N801

video

audio

Y

C

BU4052

AN7522

Vo
V2i

V1i

S-VHS

ARo

ALo

ARi2
ARi1

ALi2

ALi1

L

OUT1+
OUT1-

R

OUT2­OUT2+

10

MAIN IC 8377:

ICs functional description
UOC TDA(OM)8377

SYMBOL PIN DESCRIPTION

STAND BY output. 1 In STAND BY mode, high level (Power OFF).

For Power ON this pin will be reduced to low.
SCL 2 I2C-bus clock line
SDA 3 I2C-bus data line
TUNING 4 NC
P3.0/NTSC SW 5
KEY 6 Control keys input
VOL 7 Sound Volume cont rol PWM output
MUTE 8 Sound mute output
VSSC/P 9 Digit ground for µ-controller core and peripher y
BAND1 10
BAND2 11
VSSA 12 Analog ground of teletext decoder and digital ground of

SECPLL 13
VP2 14 2nd supply voltage TV-pr ocessor(+8V)

NC

NC

NC

TV-processor

PLL decoupling

11

DECDIG 15 decoupling digital supply of TV-processor
PH2LF 16 Phase-2 filter
PH1LF 17 Phase-1 filter
GND3 18 Ground 3 for TV-processor
DECBG 19 Band gap decoupling
AVL/EWD 20 Automatic volume leveling /EAST-WEST drive output
VDRB 21 Vertical drive B output
VDRA 22 Vertical drive A output
IFIN1 23 IF input 1
IFIN2 24 IF input 2
IREF 25 Reference current input
VSC 26 Vertical sawtooth capacitor
TUNER AGC 27 Tuner AGC output
AUDEEM/SIFIN1 *1 28 Audio deemphasis or SIF input
DECSDEM/SIFIN2 29 decoupling sound demodulator or SIF input 2
GND2 30 ground 2 for TV processor
SNDPLL/SIFAGC *1 31 narrow band PLL filter or AGC sound IF
AVL/SNDIF/REF0/
AMOUT *1

32 Automatic Volume Levelling / sound IF input / subcarrier

reference output / audio

deemphasis
HOUT 33 horizontal output
FBISO 34 flyback input/sandcastle output
AUDEXT/QSSO/

35 external audio output / QSS intercarr ier out
AMOUT *1
EHTO 36 EHT/overvoltage protection input
PLL IF 37 I F- PLL loop filter
IFVO/SVO 38 IF video output / selected CVBS output
VP1 39 supply voltage TV processor
CVBS INT 40 internal CVBS input
GND1 41 ground for TV processor
CVBS/Y 42 CVBS/Y input
CHROMA 43 C input
AUDOUT/AMOUT *1 44 audio output /AM audio output (volume controlled)
INSSW2 45 2nd RGB / YUV insertion input
R2/VIN 46 2nd R input / V (R-Y) input / PR input
G2/YIN 47 2nd G input / Y input
B2/UIN 48 2nd B input / U (B-Y) input / PB input
BCLIN 49 beam current limiter input
BLKIN 50 black current input / V-guard input
RO 51 Red output
GO 52 Green output
BO 53 Blue output
VDDA 54 analog supply of Closed Caption decoder and digital supply of

12

TV-processor (3.3 V)
VPE 55 OTP Programming Voltage
VDDC 56 digital supply to core (3.3 V)
OSCGND 57 oscillator ground supply
XTALIN 58 crystal oscillator input
XTALOUT 59 crystal oscillator output
RESET 60 reset
VDDP 61 digital supply to periphery (+3.3 V)
P1.0/INT1 62 TV/AV (AV1) / AV2 /S-VHS mode Output.
P1.1/T0 63 T V/ AV (AV1) / AV2 /S-VHS mode O utput.
P1.2/INT0 64 Remote control signal input.

AN7522/AN17821A Function : audio output

Symbol PIN Function Symbol PIN Function

Vcc 1 Power supply GND 7 ground

Out 1 (+) 2 Ch 1 output (+) In 2 8 Ch 2 input

GND(out 1) 3 Ch 1Ground VOL 9 Volume Control

Out 1 (-) 4 Ch 1 output (-) Out 2 (-) 10 Ch 2 output (-)

Standby 5 Mute input GND(out 2) 11 Ch 2 Ground

In 1 6 Ch 1 input Out 2 (+) 12 Ch 2 output (+)

STV9302A/LA78040 Function : vertical output

Symbol PIN Function Symbol PIN Function
INV IN 1 Input V OUT 5 Vertical output
VCC1 2 Power VCC2 6 Output power

supply
PUMP UP 3 Pump up power NON INV IN 7 Negative feedback
GND 4 Ground

IC voltages
TDA(OM)8377

PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

V 2.8 3.8 3.6 3.3 3.5 3.5 0.1 0.1 0 5.4 0.1 0 2.3 8 5 3

PIN 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

V 4 0 4 0.9 0.7 0.8 1.9 1.9 3.9 3.8 1.6 3.2 3.4 0 2.4 0.1

PIN 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

V 0.6 0.5 3.7 1.7 2.4 3.1 8 3.8 0 3.4 1.5 3.6 2.3 2.6 2.6 2.6

PIN 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

V 2.3 7.2 2.7 2.7 2.7 3.5 0 3.5 0.1 1.7 1.8 0 3.5 0.1 0.1 5

STV9302A/LA78040

PIN 1 2 3 4 5 6 7

V 0.7 15 -12 -15 0.3 15.9 -0.07

13

AN 7522/AN17821A

PIN 1 2 3 4 5 6 7 8 9 10 11 12

V 12 7 0 7 3.3 1.4 0 1.4 0 7 0 7

6. Test point Waveforms

2.6Vpp

H

TDA8377 PIN38

95Vpp

H

1Vpp

TDA8377 PIN21

V

H H

1.2Vpp

H

TDA8377 PIN40

95Vpp

H H

CRT KG CRT KR

0.8Vpp

V

TDA8377 PIN22

300Vpp 22Vpp

T501 PIN7

3.8Vpp

H

TDA8377 PIN53

95Vpp

CRT KB

TDA8377 PIN59

2.5Vpp

H H

TDA8377 PIN52 TDA8377 PIN51

0.9Vpp

H

TDA8377 PIN33

2.7Vpp

H

V451 B

2.5Vpp

5Vpp

H

TDA8377 PIN34

920Vpp

H

V451 C

14

Wiring diagram

15