Xoceco TK2716 Schematic

COLOR TELEVISION

TK2716

CONTENTS

Safety instruction………………………………………………………………………1 General instruction……………………………… ……………………………………… .1 Alignment instruction……………………………………………………………………2 Alignment flow ..……………………………………………………………………..2 Alignment method…………………………………………………………………..3 BLOCK DIAGRAM………………………………………………………………………... 8 MAIN IC……………………………………………………………………………….. 9 Schematic diagram………………………………………………………………….60

APPENDIX:Exploded view

Parts list

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

should be within 29.0kV on condition that the main power (B+) voltage is AC135V. And it should not

exceed 30kV in any condition.

* Keep the main power voltage at 135V 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 authentication inspection. The replacement CRT 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 manual 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 RADIATION or other hazards.

2.General instruction

2.1 Copy the standard model data to let EEPROM 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 degaussing circuit, the auto degaussing process can be finished within 1s when the

main power. only when turn on the unit at least 30min after last time turn off TV does the auto

degaussing circuit work.

2.4 If the CRT with magnetism affects color purity and convergence, when the auto degaussing

eraser. if the color purity and convergence are still not very good, then corresponding adjustment

should be done. Refer to picture tube adjustment method for adjustment.

Alignment instruction

3.1 Debugging item

a)adjust mode instruction

b)B+ voltage adjustment

c)RFAGC voltage adjustment

d)focus adjustment

e)Screen-grid voltage white balance, sub brightness adjustment

f)filed scan center, line , amplitude adjustment

g)H-scan center adjustment

3.2 Alignment flow

+B adjustment

ormal

temperature aging

Focus adjustment

AGC adjustment

White balance adjustment

Picture adjustment

Fig-1 alignment flow

3.3 Enter/exit factory adjustment method

Use remote control, press “MENU” button, then press 6483,”M”will appear on screen to show that you

have entered the factory adjustment method, press “STANDBY” to exit it.

3.4 Select adjustment item and adjust data

After entering factory adjustment mode, press 1-4 number buttons to select menu1- menu4; To enter into

MENU0~MENU5, press “CHILD LOCK” button and then the number button (5~0) to enter into relative

menus. Press “P+” and “P-” to select and “V+” and “V-”to adjust.

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 135 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) Press “V+”,”V-”to let voltage value of tuner pin AGC be 3.8 V ± 0.1 V(DC).(if the selected tuner

is changed, then the voltage of AGC should be measured again: receive VHF-H band and 60

dB RF signal, 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 ”M” 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+=135 V)can affect the high voltage directly, so be sure to let the B+

power voltage accurate. Under any state, the high voltage should not exceed 30 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 27 kV± 1 kV. d) the high voltage should not exceed 30KV with minimum brightness and contrast.

4.6 Focus adjustment

a) receive PHILIPS signal

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

b) select factory menu3

c) on the basis of blue, adjustment RD,GD of M3, let to white balance coincide with standard.

4.8 Filed scanning adjustment (fig-2)

a) receive PAL of PHILIPS test pattern signal.

b) select factory menu1

c) adjust V-SLOPE menu to let the horizontal center line of test pattern above blanking.

d) select V-SHIFT 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.

f) Adjust V.SC to optimise the vertical S correction of picture.

g) Receive NTSC PHILIPS test pattern and readjust the above items.

4.9 Horizontal scanning adjustment (Fig-3)

a) Receive PAL PHILIPS 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 M3 menu

e) Adjust VR433 to let horizontal reproduction ration of picture acceptable

f) Adjust VR432 to minimize left-right edge pincushion distortion of picture

Horizontal line

Under part banking

Fig-2 field scan adjustment

g) Adjust VR431 to minimize trapezoidal distortion

h) Exit factory menu

4.10 Sub-brightness adjustment

a) Receive PAL-D/K PHILIPS 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 PAL-D/K PHILIPS signal

b) Select OSD H and OSD V of factory menu4. Adjust OSD H and OSD V to let OSD at a specified

place.

c) Exit factory menu

4.12 Degaussing

a) The unit has and auto degaussing 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 clockwise 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 purity” and “convergence”

4.13 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 deflection yoke backward of forward until the whole green raster appears on screen,

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

4.14 Convergence correction

4.14.1 Central convergence correction

a) Turn on your TV

Fig-3 line scan adjustment

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 the 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.

4.14.2 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 the bottom 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 wedge

Chart 1 I

C standard UOC for export bus control adjustment item default setting

C TDA (NOM)8377-B-6NA E

PROM pre-set data

MI Items Variable Preset

M0 SUBCON 56(sub-contrast)

SUBCOL 56(sub-chroma)

SUBSHP 48(sub-acutance)

SUBTINT 31(sub-hue)

M1 V.SLOPE 34(field center adjustment)

V.SHIFT 27(field point adjustment)

V.SIZE 36(field amplitude adjustment)

V.SC 32(field line )

HSHIFT 32(line point adjustment)

PROGRAMA.NO 2(channel)

M2 AGCTAKEOVER 24(AGC adjustment)

SHIPPING 0(leave factory set)

M3 BT 75(adjust white balance of brightness)

CT 75(adjust white balance of brightness contrast)

SC OFF

RB 32(red cut off level adjustment)

GB 32(green cut off level adjustment)

RD 32(red cut off level adjustment)

GD 32(green cut off level adjustment)

BD 32(blue cut off level adjustment)

SB 40(sub brightness adjustment)

M4 OSD.V.POSITION 10(OSD position)

OSD.H.POSITION 5(OSD H-position)

BTSC-MODE MONO(STEORO,SAP )

BTSC-ST 13

BTSC-SP 12

BTSC-L1 1

BTSC-A1 15

BTSC-A2 0

BTSC-TC 0

BTSC-STS

BTSC-ADJ

MI Items Variable Preset

M5 MODE STANADARD(standard, soft, floweriness)

BRIGHT 75

COLOR 50

SCBRIGHT 20

YDELAYTV 12

YDELAYAV 1 2

M6 OSO 1(field over-scan switch)

AGCSPEED 1(AGC of speed)

FFI 0(IF PLL SPEED)

FMWS 1(frequency range of sound OFF=225KHZ,ON=450KHZ)

RP0 0(pre-shock and over-shock scale)

NTSCMATRIX USA

VOLPIN 0(1:push-pull output; 0: OC gate output.)

SOFT CLIP 3(white level limit)

PEAK WHITE 15(peak white limit)

CORING 0(coring noise reduction)

M7 AV2 1

SVHS 1

YUV 1

CONTRAST

VOLADJPOING 1(volume value have:1,25,50,75)

VOLVALUE 20(volume curve value:20,60,75,90)

M8 CATHOOELEVEL 7(cathode level)

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

inside)

FMATT 45(UOC sound output of amplitude) BTSC : 38

COMBFILTRE 0(N comb filter)

HEADPHONE 0(earphone function selection)

VM OPTION 0(VM function selection)

FRANCE 1 French

SPANISH 1 Spaish

POTUGUES 1 Portuguese

M9 NOM8377-B-6NA

STARTON 2(turn on)

STARTTIME 8(turn on time)

IF OFFSET 32(IF compensate)

TUNER OPTION 0(BXATB011F---X/ BXATB108F---K) 1 (BXATB017F---K) 2(XXX)

Block diagram

rCb

TUNER

POWER

UNIT

SAW

135V

24V 16V

8V 5V

3.3V

TRAP

24C08

video

bus

TDA8377

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

TDA8177

V OUT

H IN

H OUT

video

200V +15V

-15V

CRT PCB

CREEN

OCU

audio

video

CRT

video

4052

audio

N801

video

audio

BU4052

V1i

ARo

ALo

ARi2 ARi1

ALi1

AN7522

Vi1

OUT1-

OUT1+

Vi2

OUT2-

OUT2+

Vo V2i

S-VHS

MAIN IC 8377:

ICs functional description

UOC TDA8377

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 tuning Voltage (Vt) PWM output

P3.0/NTSC SW 5 Port 3.0 or NTSC output/SCART SW input, Forced NTSC selection,

Low-level output, otherwise High output.

KEY 6 Control keys input *3

VOL 7 Sound Volume control PWM output

MUTE 8 Sound mute output

VSSC/P 9 Digit ground for µ-controller core and periphery

BAND1 10 Tuner Band selection output

BAND2 11 Tuner Band selection output

VSSA 12 Analog ground of teletext decoder and digital ground of TV-processor

SECPLL 13 SECAM PLL decoupling

VP2 14 2nd supply voltage TV-processor(+8V)

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

HOUT 33 horizontal output

FBISO 34 flyback input/sandcastle output

AUDEXT/QSSO/

AMOUT *1

EHTO 36 EHT/overvoltage protection input

PLL IF 37 IF-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

INSSW2 45 2nd RGB / YUV insertion input

32 Automatic Volume Levelling / sound IF input / subcarrier reference output

/ audio

deemphasis

35 external audio output / QSS intercarrier out

44 audio output /AM audio output (volume controlled)

+ 25 hidden pages