colour tv trainer

8/13/2019 Colour tv trainer

1/90

Colour Television

Trainer

ST2651

Operating Manual

Ver 1.0

QUALIT !OLIC

To be a Global Leader of Innovative, Competitive

and Eco friendly Electronic Equipment, Software

Products and Turn-ey Solutions for Industry and

Tec!nolo"y Trainin"# $e will ac!ieve t!is by

en!ancin" Customer Satisfaction based on

%esearc!, &odern manufacturin" tec!niques and

continuous improvement in 'uality of t!e

products and t!e Services# T!e ey drivers to

"rowt! will be focus on Employees and

Customers, (se of latest Tec!nolo"y, Intense

&aretin", Service Support and )i"! Et!ical

Practices#

*n IS+ . / 0 company

1-.., Electronic Comple2

Pardes!ipura, Indore- 130., I45I*

P!/ .-67.- 0338879, 0367.

:a2/ .- 67.- 0333817

E-mail/ info;scientec!#b


2/90

ST2651

S"iente"# Te"#nologies !vt. Lt$. 2


3/90

ST2651

Colour TelevisionTrainer

ST2651

Ta%le o& Contents1. Introduction 3

2. :eatures 8

'. Tec!nical Specification 6

(. Safety Precautions 9

5. Trainer Controls

6. =loc dia"ram ..

). T!eory of +peration .0

*. Gettin" Started .1+. E2periments

a. E2periment . .1

To study t!e circuit description of %: Section >Tuner Section?

%. E2periment 0 .3

To study t!e %: Section t!rou"! Test Points

". E2periment 7 .8

To study t!e fault simulation and step-by-step fault findin" procedure

of %: Section

$. E2periment 1 .

To study t!e detail circuit description of @I: section

e. E2periment 3 0.

To study t!e @I: Section t!rou"! Test Points

&. E2periment 8 0.


of @I: Section

g. E2periment 6 07

To study t!e detail circuit description of @ideo A C!roma section

#. E2periment 9 08

To study t!e @ideo A C!roma section t!rou"! Test Pointsi. E2periment 09


of @ideo A C!roma Section

,. E2periment . 77

To study t!e detailed circuit description of )ori


4/90

ST2651

l. E2periment .0 78


of )oriS&PS?

Section

10. Glossary 89

11. General 5etails for Servicin" 68

S"iente"# Te"#nologies !vt. Lt$. (


5/90

ST2651

12. Preset layout dia"ram 91

1'. *ctual S!ortin" S!unt Position of Bumpers 93

1(. $arranty 9815. List of &aor Service Centres 96

16. List of *ccessories 99



6/90

ST2651

Intro$u"tion

S"iente"# Colour TV trainer ST2651 is an ideal trainin" equipment to teac! t!e

operation of colour television receivers# It is demonstrator cum trainer specificallydesi"ned for t!e study of worin" of television# T!e controls are placed actually at

t!e places as t!ey are in t!e circuit sc!ematic and t!us trainee can loo at it in any

section, A can see components of t!e section and able to study it t!orou"!ly# T!e

function controls are adustment control fully adustable to t!e trainee and to verify

t!eir affect on t!e worin" of t!e television#

+ne of t!e main features of t!is trainer is fault simulation to train on actual fault

findin", by simulatin" faults in t!e instruments# T!e faults created in t!e instruments,

no way affects nor dama"e t!e instrument# T!e instructor can introduce faults of

!isD!er c!oice from t!e standard 19 faults and as trainee student to probe into it and

to find out t!e cause of t!e fault# T!is way trainee "ets complete insi"!t of trainin" offaults in t!e electronic circuit#

T!e complete circuit of colour T@ receiver is printed on sin"le printin" PC=# Eac!

section is colourfully separated# Test point details wit! typical volta"es and

waveforms are provided in t!e manual# T!e trainer !as a special desi"n of slidin"

main board wit! loc facility# It can be also used as a normal destop colour T@

receiver# In addition t!e trainer will be of immense value to practicin" en"ineers and

students en"a"ed in study of T@ receiver#

T!e trainer !as been desi"ned to meet t!e requirements of electrical and electronics

en"ineerin" student at t!e de"ree level# It will also meet t!e compre!ensive practical

study on T@ en"ineerin" in polytec!nics and tec!nical institutes# T!e trainer !asbeen so presented t!at any en"ineerin" student wit! a basic nowled"e of t!e various

electronic buildin" blocs and fundamentals of communication system will !ave no

difficulty in understandin" t!e trainer#

$e !ope our attempt will !elp t!e user to understand t!e worin" of colour

television receivers#



7/90

ST2651

eatures

Most "opa"t $esign

Sli$ing ain %oar$ it# lo"- is &a"ilit3

Manual an$ reote "ontrol operation

ault "reation an$ $iagnosis

55 test points

Colour&ul separation o& ea"# se"tion

4o sol$ering$esol$ering is re/uire$ to siulate &ault

T#e trainer or-s as noral TV #en t#e "ontrols are noral

All t#e varia%lesa$,ustents Via7 8eig#t7 Linearit37 9#ite %alan"e et". area""essi%le on t#e s"reen itsel& it# On S"reen :ispla3 ;OS: 78D3. cms 5ia"onal

@ input ipe$an"e > 63

Cir"uit lo"-s > System Control Circuit, @ideo I:, Sound section,

Tuner section, )ori 163 763

4o. o& aults > 19

4o. o& Test !oints > 33

I. . re/uen"3 > @ideo- 79#&) 01@# &a2#

Operating voltage &or =8T > ..@

!oer Suppl3 > 00@, .H, 3 ) 63$atts >appro2?

use > 0*

:iensions ;< > $8.537)81

9eig#t > "70 >appro2?

S"iente"# Te"#nologies !vt. Lt$. *


9/90

ST2651

Sa&et3 !re"autions

@olta"es and waveforms of E)T, S&PS transformer and !ori


10/90

ST2651

Trainer Controls

ront !anel Controls

!oer O4O

S

Menu

Vol

Vol

!rog

Au$ioVi$eo In

Sensor

ront Lo"-

@ear !anel Control >

Aerial Ba"-

@eote Controls >

!oer

Mute

4u%er uttons ;0+ To turn t!e T@ +4 >It wors w!en power +4?

> To display t!e menu on screen#

> To decrease t!e volume >durin" on screen

display mode it also used to set t!e selected

items?

> To increase t!e volume >durin" on screen

display mode it also used to set t!e selected

items?

> To cyclically select c!annels >durin" on screen

display mode t!ese switc!es are used to select

items?#

> Socets are provided to connect audio - video

Si"nal from ot!er audio - video equipments?

> It is a remote sensor w!ic! receives t!e infrared

si"nals from t!e remote control#

> To open t!e enclosure so t!at you can pull t!e

PC= outside t!e cabinet for testin" purpose?

> To connect t!e cables#

> To turn t!e T@ +4 from stand by mode#

> To mute volume#

> To select t!e c!annels directly#

> To switc! c!annel numbers amon" sin"le di"it

double di"it and triple di"it#> To select t!e c!annels cyclically# *lso used for

selectin" t!e items durin" +4 screen display

mode#

> To adust t!e volume# 5urin" on-screen display

mode t!ese buttons are used to set t!e selected

items#



11/90

ST2651

Menu >

I

II

III

IV

AV

!!

S"an

Sap

Doo ; V? ey#

> =y pressin" t!is switc! fourt! time t!e

followin" &enu appears on t!e screen

a.Store %.En"lis! ".)indi:unctions can be selected by pro"# D eys

and stored by selectin" Store and pressin" @+L

>? ey,

> T!is mode is provided to connect *udio -

@ideo Equipment wit! T@#

> To restore t!e values of =ri"!tness contrast,

colour, @olume stored in PP#

> +n activatin" t!is feature t!e T@ displays t!e

pro"rams in all t!e c!annels for a few seconds#

> It enables one s!ot e2c!an"e of pre-tuned

c!annels between two pro"rams#

> T!is facility allows t!e ima"e on screen to

e2pand and fill t!e screen#

> T!is feature allows you to loc a few c!annels

by your remote control, so as to prevent your

c!ildren from watc!in" t!em#



12/90

ST2651

lo"- :iagra

S"iente"# Colour TV trainer ST2651

ig. 1



13/90

ST2651

T#eor3 o& Operation

T!e basic obective of colour T@ trainer is to study all t!e si"nals or volta"es in

different sections of t!e circuit# T!e %: si"nal received by antenna is fed to t!e tuner

section by antenna wire# Tuner section separates t!e I: si"nal from received %:

si"nals# T!ese I: si"nals are supplied to @I: and SI: section# T!is I: si"nals are !ere

amplified by video I: amplifier and t!en detected by video detector# So in t!is section

composite colour video si"nal is obtained# Sound si"nals are separated from t!is

composite colour video si"nal by a SI: filter and t!en fed to sound I: amplifiers#

Sound I: amplifiers amplify t!e sound si"nal w!ic! is t!en detected by :& detector#

*udio amplifier amplifies t!e detected audio si"nal w!ic! are a"ain amplified by

audio output amplifier and fed to speaer#

Composite colour video si"nals are supplied to videoD c!roma section >IC C5689?#

T!is video si"nal contains )ori


14/90

ST2651

K #3H Green #7H %ed #.. H =lue

$!en t!is equation is satisfied we can "et t!e better results on t!e screen#

T!e power supply circuit provides t!e necessary operatin" volta"es for t!e instrumentinput *C supply 07@ is provided to brid"e rectifier# Its output is 7@ 5C# T!is 5C

volta"e is provided to S&PS transformer# T!is Transformer provides 00@, ..@,

77@ 5C supplies w!ic! are used in various circuit sections#

E)T transformer supplies 00@ >E)T? acceleratin" potential to final anode of

picture tube# E)T transformer also produces *:C fly bac pulses# :ocus and screen

volta"e are produced by E)T Transformer fed to picture tube at G0 and G1 >"reed?#

)eater filament "ets supply by E)T transformer pin no# #

T!e main controllin" system for t!is trainer it is system control section# It is IC

:+45*1ST# T!is system controls IC control# *ll t!e remote control functions as

well as front panel control lie volume, bri"!tness, contrast, colour menu etc# T!is ICsystem is also related wit! memory section, w!ic! can store t!e c!annels in its

memory and same ot!er functions can be stored in it#

S"iente"# Te"#nologies !vt. Lt$. 1(


15/90

ST2651

Eetting Starte$

.# Plate t!e television monitor Supply on t!e base unit

0# Connect t!e antenna cable to t!e base unit

7# Connect one end of 08 pin flat cable to base unit A t!e ot!er to monitor

1# Connect one end of 9 pin octal cable to base unit A t!e ot!er to monitor

3# Connect one end of .. pin octal cable to base unit A t!e ot!er to monitor

8# Connect t!e *C mains cord to t!e monitor

=perient 1

O%,e"tive >

To stu$3 t#e "ir"uit $es"ription o& @FSe"tion ;Tuner se"tion

T!e %:-Section is mainly consistin" of %: Tuner# T!is tuner !as %: amplifier, a

mi2er and a local oscillator#

T!e antenna receives t!e radio frequency >%:? waves from t!e atmosp!ere and

converts t!em into correspondin" si"nal variations# T!ese %: variations are fed to %:

tuner# T!e input impedance of %: Tuner is 63 o!ms# T!e antenna system and co-a2ial

cable s!ould be properly matc!ed# If a co-a2ial cable of 63 o!ms impedance is

employed, t!ere is no need of any e2tra matc!in" device between cable and antenna

socet at t!e receiver# =ut in case of a feeder wire of 7 o!ms is employed, and t!en

an impedance matc!in" transformer >763o!ms? is added between feeder and

antenna socet at t!e receiver# T!ere is also a need of impedance matc!in" between

output terminals of antenna and co-a2ial cable or feeder wire# T!e %: tuner selects t!e

si"nal of t!e desired c!annel amplifies it and converts in to Intermediate frequencies

>I:?# T!e video I: is at 79#&)< and sound I: is at 77#1&)=C316?# $!ic! switc! on t!e transistor and so tunin" volta"e is -77@ appro2# is

obtained at T@ terminal >TP.?#

:ollowin" are t!e various terminal of %: tuner, w!ic! are provided in t!e form of test

point >TP? in our trainer it#

U > T!e system control IC provides t!e (): band selection volta"e# T!is

volta"e switc! +4 t!e transistor, !ence (): band is selected#

8 > @): band III selection volta"e available from system control IC t!rou"!



16/90

ST2651

switc!in" transistor at )= pin#

L > @): band I selection volta"e available at L= pin from system control IC

t!rou"! switc!in" transistor#

TU > C!annel selection volta"e is available at t!is pin t!rou"! transistor# It is

varyin" from -77@ durin" c!annel selection#

AEC> *utomatic Gain Control volta"e is available at t!is pin from IC689#

AT > *utomatic :ine Tunin" volta"e is available at t!is pin from IC689#

M > It is tuner sectionMs Power Supply pin# )ere .0 volt appro2# is available#

I > Intermediate frequency output si"nal from tuner is available at I: pin

=perient 2

O%,e"tive >

To stu$3 t#e @ se"tion t#roug# test points.

T!21 lue >

Tuner section >(=? .#9@ appro2# if (): band is selected ot!erwise @#

+n selectin" t!e (): band system control IC feeds (): band switc!in" output from

pin 7 >.@ appro2? so .#9@ appro2# is obtained !ere >for ot!er band selection it is

@?

T!1+ lue >

Tuner section >T(? selection -9@ appro2 varyin" durin" c!annel#

Pin 77 of system control IC provides t!e tunin" pulse output to T@ terminal t!rou"!transistor '7 >=C316?

T!1* lue >

Tuner section >)=? ot!erwise @ >@): III? .#9@ appro2# if @): III band is

selected#

+n selectin" t!e @): III band system control IC feeds @): III band switc!in" output

from pin no# 0 >.@ appro2#?# So .#9@ appro2# is obtained !ere A >for ot!er band

selection it is @?

T!20 lue >

Tuner section 8#9@ appro2 >*GC? adustable#T!is volta"e is used for automatic "ain controllin" purpose and comin" from IC689#

T!1) lue >

Tuner section >L=? .#9@ appro2# if @): I band is selected ot!erwise @ >@): I?

+n selectin" @L band system control IC provides @L band I switc!in" output from

pin . >.@ appro2#? So .#9@ appro2# is obtained !ere A for ot!er band selection it is

@#

T!16 lue >

Tuner section *:T# 3#6@ appro2#



17/90

ST2651

T!is volta"e is obtained from pin .7 of IC689 for t!e purpose of automatic fine

tunin"#

T!1( @e$ >Tuner section >&=? ..@ appro2 supply for Tuner section#

It is obtained from )ori

Tuner section >I:? Tuner +utput si"nals accordin" to band selection#

ig. 2

=perient '

O%,e"tive >

To stu$3 t#e &ault siulation an$ step%3step &ault &in$ing pro"e$ure o& @se"tion.

ault Insertion >

ault 1 > 4o pi"ture onl3 lo "ontrast sno on s"reen.

ault Insertion> %emove t!e s!ortin" s!unt from 0A7 pin and place it between pin

.A0 of umpers B.

S3ptos > Even antenna is connected but t!en also t!ere is no picture only sound is

present wit! low contrast#

ault Se"tion > Tuner Section

!ro"e$ure >

C!ec power supply at TP.1 >&=? of tuner section, it s!ould be .0@ if not

T!en C!ec .0@ supply at TP.7 if it is +

%emove t!e s!ortin" s!unt from pin .A0 and place it between pin 0A7 of

umpers B.#

%esult / 4ow you s!ould "et .0@ at TP.1#

ault 2 > 4o pi"ture7 4o transitting soun$.

S"iente"# Te"#nologies !vt. Lt$. 1)


18/90

ST2651

ault Insertion > %emove t!e s!ortin" s!unt from 0A7 pin and place it between pin

.A0 of umper B7

S3ptos >4o picture, 4o sound and tunin" is not possible#ault Se"tion > Tuner Section#

!ro"e$ure >

C!ec t!e volta"e at TP1>77@ appro2? if it is not present t!en,

Trac may be open or components are faulty#

%emove t!e s!ortin" s!unt from pin .A0 and connect it between 0A7 of umper

B7#

%esult / 4ow you s!ould "et picture wit! + sound#

ault ' > 4o !i"ture7 4o transitting soun$.


.A0 of umper B1

S3ptos >4opicture, t!ere is only snow on A tunin" not possible

ault Se"tion > Tuner section#

!ro"e$ure >

:irst c!ec t!e antenna wire and antenna# If it is properly connected t!en

Select t!e auto tunin" mode# It starts wit! @L =and5urin" @L =and tunin" period .0@ will be obtained at TP-.6,

5urin" @) =and tunin" period .0@ will be obtained at TP-.9

5urin" @): =and tunin" period .0@ will be obtained at TP-0., if it is not

!appenin" t!en,

C!ec volta"e at collector of transistors '*0, '*7, '*1 it s!ould be .0@,if it is + t!en,

C!ec t!e volta"e at Emitter of transistor '*0, '*7 and '*1, it s!ould be.0@ if it is + t!en

Transistor may be faulty or trac may be open between TP-.7 and emitter oftransistor, '*-0, '*-7, and '*-1#

%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7 of umperB1#

%esult / 4ow you s!ould "et possible tunin" and "et picture#ault ( > @) =and is not selected

ault Insertion > %emove t!e s!ortin" s!unt from pin 0A7 and place it between pin

.A0 of umper B3

S"iente"# Te"#nologies !vt. Lt$. 1*


19/90

ST2651

S3ptos >4o picture, no transmittin" sound, only snow#but si"nal received from

antenna in @) band# Is of "ood quality#

ault Se"tion >Tuner section#!ro"e$ure >

:irst c!ec t!e volta"e at TP-.7, it s!ould be .0@ appro2, if it is not present

t!en,

C!ec t!e volta"e at TP.9, if it is not present t!en, C!ec t!e volta"e at transistor '*7, if it is not present t!en, Transistor may be faulty or trac may be open between emitter of Transistor

'*7 A TP.7#

%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7 of

umperB3#

%esult / 4ow you will "et @) =and selected A "ood picture too#ault 5 > !i"ture tilte$ to one si$e. Soun$ OG.


.A0 of umpers B8

S3ptos > )ori

@ary t!e preset of *GC# If variation of picture is not found to be + t!en#

C!ec t!e volta"e variation by eepin" t!e test point at TP-0 by varyin" t!epreset @%.3.# If no variation is present, c!ec t!e preset# If it is proper t!en#

%esistance %.3 may be faulty, If it is + t!en, C!ec t!e continuity between %.3 and TP0# If it is not proper t!en# %emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7 of umper

B8#

%esult / Proper picture wit!out any s!ain" symptoms is observed#

S"iente"# Te"#nologies !vt. Lt$. 1+


20/90

ST2651

=perient (

O%,e"tive >

To stu$3 t#e $etail "ir"uit $es"ription o& VI se"tion.T!is section includes @I: and SI: sections# T!is trainer uses IC.. >C5689? for

@I: and SI: sections# T!e si"nals at if terminal >TP.3? of tuner section are fed at t!e

base of transistor '.8. >C799*? t!rou"! couplin" capacitor C.8. >.f?# T!is

amplified I: si"nals are available at collector of t!is transistor and t!en fed to saw

filter t!rou"! capacitor C.87 >#.f? collector of pre amplifies transistor "ets positive

supply by resistances %.81 >00? and %.83 >16?# =ase biasin" is "iven by

resistance %.87 >3#8? and %.80 >.? to base of pre amplifier and its emitter is

"rounded by %.88 >06?# +utput of saw filter is fed to pin 6 and 9 of IC.. >IC689?

by coil L.0 >T%: .130? %.. >90? and C.. >#.f? networ# Pin 6A9 are @I:

amplifier pins# T!e si"nal from t!is section "oes to video detector after amplification#@ideo detector detects line video si"nal and amplified by video pre amplified section#

Composite colour video si"nals are obtained at pin no#.3# T!e si"nal is s!own at

TP07#T!is composite si"nal also !as SI: si"nal of 3#3&)3#3&)


21/90

ST2651

&. Sound I: limitation and amplification#

g. :& detection#

#. *ttenuation and providin" audio output#

VI an$ Soun$ I Cir"uit

ig. '



22/90

ST2651

=perient 5

O%,e"tive >

To stu$3 t#e VI se"tion t#roug# &olloing test points!in ' o& IC VI se"tion

*udio output si"nal from IC689, "oes to sound amplifier 6 @5C#

T!2' @e$ VI se"tion

Composite video si"nal >Pin no#.3 of IC689? ##

ig. (

=perient 6

O%,e"tive >

To stu$3 t#e &ault siulation an$ step %3 step &ault &in$ing pro"e$ure o& VI

se"tion.

ault 6 > 4o Soun$7 4o !i"ture onl3 plane raster on t#e s"reen.


.A0 of umper B0

S3ptos > T!ere is no sound nor picture on t!e screen# +nly plane raster is present#

ault Se"tion > @I: Section

!ro"e$ure >

C!ec power supply at pin no#0 of IC.. >IC689? If not t!en, C!ec .0@ at TP.7 if it is + T!en may be trac open between TP.7 and Pin 0 of IC..

If not t!en c!ec t!e continuity connection between TP.7 and TP8#

%emove t!e s!ortin" s!unt from pin .A0 and place it between pin 0A7 ofumper B0#

%esult/ 4ow you s!ould "et .0@ at pin no#0 of IC..#A "ood picture wit!sound



23/90

ST2651

ault ) > !lane @aster on t#e S"reen.

ault Insertion > %emove t!e s!ortin" s!unt from pin 0A7 and place it between pin

.A0 of umper B7.S3ptos > +nly plane raster on t!e screen wit!out any sound#

ault Se"tion > VI Se"tion.

!ro"e$ure >

:irst c!ec t!e composite colour video si"nal at pin no.3 of IC..# If it is +t!en,

C!ec t!e composite colour video si"nal at pin no#7 of IC3.# T!e components connected between TP07 and pin no#71 of IC3. may be

faulty# If t!ese are + t!en, C!ec t!e trac between TP07 and pin no# 7 of IC3.# %emove t!e s!ortin" s!unt from pin .A0 and connect it between 0A7 of

Bumper B7.#

%esult / 4ow you s!ould "et clear picture wit! sound#ault * > 4o !i"ture. 4o transitting soun$.

ault Insertion > %emove t!e s!ortin" s!unt from pin .A0 and place it between pin

0A7 of umper B76

S3ptos >4o Picture, t!ere is only snowault Se"tion > @I: Section

!ro"e$ure >

:irst c!ec t!e antenna wire and antenna# If it is properly connected t!en, C!ec t!e tuner volta"e .0@ at TP-.1# If it is + t!en tuner may be faulty# 4ow try to "et t!e picture wit! t!e !elp of *uto tunin"D:ine tunin"# If you are

not "ettin" t!e picture t!en,

C!ec t!e 77volt at TP1 5*.7# If it is + t!en, 5urin" t!e auto mode, c!ec t!e volta"e variation of @ to 9@ at emitter of T%

'0# If it is not varyin" t!en,

Trac may be trac open between 5*.7 and '0# %emove t!e s!ortin" s!unt from pin 0A7 and connected between .A0 Bumper

B76#

%esult / 4ow you s!ould "et clear picture wit! sound#

S"iente"# Te"#nologies !vt. Lt$. 2'


24/90

ST2651

ault + > !i"ture it# $istorte$ Soun$#

ault Insertion > %emove t!e s!ortin" s!unt from pin .A0 and place it between pin

0A7 of umper B6S3ptos > T!ere is picture wit! snow and distorted sound# >In case of improper

antenna plane raster will appear

ault Se"tion >@I: Section#

!ro"e$ure > 4ote > To find out t!is problem tae si"nals from colour pattern

"enerator ST086 instead of antenna#

:irst c!ec t!e I: si"nal at TP.3, if it is + t!en, C!ec t!e I: Si"nal at TP00# if it is + t!en,

C!ec t!is si"nal at =ase of transistor '.8., If it is + t!en, Transistor may be faulty# If it is + t!en 4ow c!ec t!e I: si"nal at t!e end of capacitor C.87 connected to saw filter, if

it is wea t!en

C!ec capacitor C.87 is connected wit! "round or not#

%emove t!e s!ortin" of s!unt from pin 0A7 and connect it between .A0 ofumper B6#

%esult / 4ow you s!ould "et "ood picture wit! + sound#

=perient )

O%,e"tive >

To stu$3 t#e $etail "ir"uit $es"ription o& Vi$eo H C8@OMA se"tion.

S"iente"# Colour TV trainer ST2651uses IC C5689 >IC3.? for video A c!roma

section# @ital part of t!e IC is used for c!roma section# :or c!roma section pin no#.-

07 and pin no#79-10 are used, ot!er pins are used for @ideo section# :or c!roma

section followin" are t!e main sub sections in t!e IC /

C!roma amplifier

Colour oscillator

Colour iller detector

&atri2

Luminance >? si"nal amplifier#

@I: section IC.. >C5689? pin no#.3 supplies t!e composite colour video si"nal to

t!e inverter pin no# 7 of IC3. >C5689? by circuit made up of L.3 >7#7)? %39

>77?, Trap3#3&)< >ceramic filter? and L0. >.0)?# In inverter section t!is si"nal

is amplified as well as detected, *fter detection si"nal "oes to amplifier w!ic! is



25/90

ST2651

in built in IC, %emainin" amplified composite colour and sin si"nal are obtained at

pin no# 1 of t!is IC, t!en fed to pin no# 3 of t!is IC t!rou"! resistance %3. >90?,

C38 >.9pf? and C30 >.pf?# Pin no#3 is =and pass amplifier pin# Si"nal "oes to

band pass amplifier by t!is pin and amplified !ere# *mplified si"nal is obtained atpin no#9#

:rom pin no#9 t!e si"nal fed to pin no#. of t!is IC by passin" it t!rou"! c!roma trap

circuit# T!is trap circuit consists of @%33. >.? C36 >#.f?, C39 >.3Pf?, C30

>.)? N30 >5L6. delay line?, L33. >T%:31.9? %3. >16? and C3 >#.:?#

:rom pin no#9 t!is si"nal is also fed to pin no#.6 of t!is IC in t!e form of colour sin

si"nal by resistance %3 >.#3?, C3. >#.:? pin no#.6 is of matri2 section# Pin no#

1. is contrast control pin# Pin no#1. "ets t!e contrast control si"nal from pin no#76 of

system control IC t!rou"! resistance %18 >38?, %13 >.#3? and %0.7 >16?# Pin

no#1 of t!is IC is bri"!tness control pin# Pin no#79 of IC. >system control section?

supplies t!e bri"!tness control si"nals at t!is pin t!rou"! resistance %1. >.?, %38* >16?, %0.0 >.?# Pin no#6 of IC3. >C5689? receives t!e colour control si"nals

from pin no#78 of IC. t!rou"! resistance %16 >.?, %10 >.0? and %33 >0#0?#

Pin no#0 of IC3. >C5689? is output pin of "reen colour si"nal# Green colour

output si"nal from t!is pin is fed to base of "reen colour amplifier transistor# In t!e

same way red colour si"nal obtained at pin no#0. of t!is IC and t!en fed to base of red

colour output transistor '36 >C07.?# =lue colour si"nal obtained at pin no#00 of

t!is IC and t!en fed to base blue colour output transistor '3 >C07.?#%- si"nals A

=- si"nals#

si"nals from pin no#10 of t!is IC are fed to pin no#7 of t!e same IC t!rou"!

resistance %07 >.#3?, %0. >.#3? arid capacitor C01 >#16:? circuit networ#Luminance si"nals are out from pin no#07 of t!is IC and fed to base of luminance

amplifier transistor#

'00 >0S* ..3? t!is transistor amplifies t!e si"nal and out t!e si"nal by its emitter,

w!ic! is t!en fed to all t!e t!ree emitters of t!ree colour output transistors#

Pin no#7 to 76 of IC3. >C5689? wors for !ori


26/90

ST2651

ig. 5



27/90

ST2651

=perient *

O%,e"tive >

To stu$3 t#e vi$eo H "#roa se"tion t#roug# &olloing test points.T!26 lue @ideo A C!roma section .0@ >appro2#?

T!2* lue @ideo A C!roma section Colour composite video si"nal

ig. 6

T!2+ @e$ @ideo A C!roma section Inverted Colour composite

@ideo si"nal

ig. )

T! '1 @e$ @ideo A C!roma section Luminance Si"nal#

ig. *

T!'( lue @ideo A C!roma section .@ >appro2?



28/90

ST2651

T!') lue @ideo A C!roma section 1#17&)< sub carrier frequency

ig. +

T!'* lue @ideo A C!roma section .0 @ >appro2?

T!'+ @e$ @ideo A C!roma section for colour adustment#

To observe Colour burst si"nal at Pin no# 3 of IC3., connect pattern "enerator

>colour bar pattern? at antenna socet#

ig. 10

S"iente"# Te"#nologies !vt. Lt$. 2*


29/90

ST2651

=perient +

O%,e"tive >

To stu$3 t#e &ault siulation an$ step %3 step &ault &in$ing pro"e$ure o& Vi$eo H"#roa se"tion

ault 10 > T#ere is 3ello s#a$e "olour on t#e s"reen it# OG !i"ture.

ault Insertion > %emove t!e s!ortin" s!unt from pin .A0 and connect it between

0A7 of umper B03#

S3ptos >T!ere is "ood picture on t!e screen wit! yellow s!ade colour

ault se"tion >@ideo A C!roma section

!ro"e$ure >

C!ec pin no#00 of IC3. >IC689? it s!ould be 6#0@ appro2# If it is not t!en

IC may be faulty#

$e now t!at if t!ere is yellow s!ade on t!e screen it means blue colour is

absent

C!ec circuit of pin no#00 of IC3. >=- output? it s!ould be 6#0@ appro2# at

= terminal >=er" strip pin?, if it is not#

T!ere may be trac open between t!is = terminal and pin no#00 of IC3.

%emove t!e s!ortin" s!unt from pin 0A7 and connect it between .A0 of umper

B03#

%esult / 4ow you s!ould "et picture in normal colours#

ault 11 > T#ere is "3an s#a$e "olour on t#e s"reen it# OG pi"ture.


0A7 of umper B01

S3ptos > Sound and picture + only screen !as cyan colour s!ade

ault se"tion >@ideo A C!roma section

!ro"e$ure >

$e now t!at if t!ere is cyan colour on t!e screen it means t!at red# colour is

absent

C!ec pin no#0. of IC3. it s!ould be 6#0@ appro2# ,if not IC may be faulty

C!ec t!is volta"e at % terminal, if it is not t!en

T!ere may be trac open between pin no#0. of IC3. A % terminal#

%emove t!e s!ortin" s!unt from pin 0A7 and connect it between .A0 of umper

B01#

%esult / 4ow you s!ould "et picture wit! normal colours#



30/90

ST2651

ault 12 > T#ere is agenta s#a$e "olour on t#e s"reen it# OG pi"ture.


0A7 of umper B07S3ptos > Sound and picture + wit! ma"enta s!ade

ault Se"tion >@ideo A C!roma section#

!ro"e$ure >

$e now t!at if t!ere is ma"enta colour on t!e screen it means t!at "reen

colour is absent

C!ec pin no#0 of IC3. it s!ould be 6#0@ appro2# >if not t!en IC may be

faulty? if + t!en,

C!ec t!is volta"e at G terminal# If it is not t!en T!ere may be trac open between pin no#0 of IC3.AG terminal

%emove t!e s!ortin" s!unt from pin 0A7 of and connect it between .A0 of

Bumper B07

%esult / 4ow you s!ould "et picture wit! normal colours

ault 1' > :ull Coloure$ !i"ture


0A7 of umper B.

S3ptos >T!ere is dull picture >4e"ative type? on t!e screen wit! full colours#ault Se"tion> @ideo and C!roma Section

!ro"e$ure >

C!ec t!e luminance si"nal at pin no#07 of IC3.#If it is not t!en IC may be

faulty, if it is + t!en,

C!ec t!is luminance si"nal at base of '00 >..3?# If it is not !ere t!en,

T!ere may be trac open between pin no#07 of IC3. and base of T00#

%eplace t!e s!ortin" s!unt from 0A7 and connect it between .A0 of Bumper

B.# %esult /Turn on t!e instrument, you s!ould "et "ood picture on t!e screen#

ault 1( > !i"ture is verti"all3 rolling it# OG soun$


0A7 of umper B0.

S3ptos > T!ere is + sound from t!e trainer it but picture is vertically rollin"#

ault Se"tion > @ideo and C!roma Section

S"iente"# Te"#nologies !vt. Lt$. '0


31/90

ST2651

!ro"e$ure >

C!ec vertical sync pulse at pin no#78 of IC3. >C5689?# If it is + t!en,

C!ec t!e pulse at pin no#09 of IC# If it is not t!en,

T!ere may be trac open between t!ese two pins or %77 >7? or capacitor,

%eplace t!e s!ortin" s!unt from pin 0A7 and connect it between .A0 Bumper

B0.#

%esult / 4ow s!ould "et clear picture wit! sound#

ault 15 > 4o "olour variation#

ault Insertion > %emove t!e s!ortin" s!unt from pin 0A7 and connect it between

.A0 of umper B06

S3ptos >T!ere is "ood picture wit!out colour variation it means blac A w!itepicture#

ault Se"tion > @ideo and C!roma section#

!ro"e$ure >

:irst c!ec t!e volta"e variation of IC3. at pin no#6 It s!ould be 7#3@ to 8#3@appro2## If it is not t!en,

C!ec t!e volta"e variation at TP30# If it is + t!en, C!ec t!e continuity of trac between TP30 A Pin no#6of IC3. If no

continuity is present, t!en %emove t!e s!ortin" s!unt from .A0 connect it between 0A7 of umper B06#

%esult / 4ow you s!ould "et colour picture wit! proper variation#

ault 16 > 4o "olour it# OG soun$.

ault Insertion > %emove t!e s!ortin" s!unt from pin 0A7 and connect it between

.A0 of umper B09

S3ptos > Good picture wit!out colour w!en colour control is set to ma2#

ault Se"tion > @ideo A C!roma section#

!ro"e$ure >

$e now t!at if t!ere is =D$ picture on t!e screen it means colour burst is absent#

So first c!ec si"nal at %3. >90%?, t!ere s!ould be composite video si"nal, ifit is + t!en,

C!ec t!e colour brust si"nal at Pin no#3 of IC3., if it is not present t!en, T!ere may be trac open between IC3. at Pin no#3 and %3. >90%?# %emove t!e s!ortin" s!unt from Pin .A0 of umper B09 and connect between

Pin 0A7#



32/90

ST2651

%esult / 4ow you s!ould "et colour picture#ault 1) > 4o "olour it# OG soun$.

ault Insertion > %emove t!e s!ortin" s!unt from pin 0A7 and connect it between.A0 of umper B08

S3ptos >Good picture wit!out colour w!en colour control is set to ma2

ault Se"tion > @ideo and C!roma section

!ro"e$ure >

:irst c!ec t!e sub carrier frequency 1#17&)< at TP-76# If it is not present t!en#

crystal may be faulty, if it is + t!en, C!ec t!e continuity of trac of Pin no#.7A.3 of IC3.# If no continuity is

present t!en,

%emove t!e s!ortin" s!unt from pin.A0 connect it between 0A7 of Bumper B08# %esult / 4ow you s!ould "et colour picture#ault 1* > T#ere is %lue s#a$e "olour pi"ture it# OG Soun$

ault Insertion1 > %emove t!e s!ortin" s!unt from pin .A0 and connect it between

0A7 of umper B01


0A7 of umper B03

S3ptos >Sound and picture + only screen !as blue colour s!ade#

ault Se"tion >@ideo and C!roma section#

!ro"e$ure >

C!ec pin no#0. of IC3. it s!ould be 6#0@ appro2, if not IC may be faulty

C!ec t!is volta"e at % terminal, if it is not t!en T!ere may be trac open between pin no#0. of IC3.A% terminal# C!ec pin no#0 of IC3. it s!ould be 6#0@ appro2# >if not t!en IC may be

faulty? if + t!en,

C!ec t!is volta"e at G terminal# If it is not t!en T!ere may be trac open between pin no#0 of IC3.AG terminal%emove t!e s!ortin" s!unt from pin 0A7 and connect it between .A0 of umper B01

%emove t!e s!ortin" s!unt from pin 0A7 and connect it between .A0 of umper B07

%esult / 4ow proper picture wit! sound is observed#



33/90

ST2651

ault 1+ > T#ere is green "olour s#a$e "olour pi"ture.


0A7 of umper B03


0A7 of umper B01

S3ptos >Sound and picture + only screen !as Green colour s!ade#


!ro"e$ure >

C!ec pin no#00 of IC3. >IC689? it s!ould be6#0@ appro2# If it is not t!en

IC may be faulty#

C!ec circuit of pin no#00 of IC3. >=- output? it s!ould be6#0@ appro2# at= terminal >=er" strip pin?, if it is not#

T!ere may be trac open between t!is = terminal and pin no#07 of IC3. C!ec pin no#0. of IC3. it s!ould be 6#0@ appro2# ,if not IC may be faulty

C!ec t!is volta"e at % terminal, if it is not t!en

T!ere may be trac open between pin no#0. of IC3.A% terminal %emove t!e s!ortin" s!unt from pin 0A7 place it between .A0 umper B03 #if It

is not proper t!en,

%emove t!e s!ortin" s!unt from pin 0A7place it between .A0 of umper B01 %esult/ Proper picture wit! sound is observed#ault 20 > T#ere is re$ "olour s#a$e pi"ture.


0A7 of umper B03


0A7 of umper B07

S3ptos >Sound and picture + only screen !as red colour s!ade#


!ro"e$ure >

C!ec pin no#00 of IC3. >IC689? it s!ould be6#0@ appro2# If it is not t!en

IC may be faulty#

C!ec circuit of pin no#00 of IC3. >=- output? it s!ould be6#0@ appro2# at= terminal >=er" strip pin?, if it is not#

T!ere may be trac open between t!is = terminal and pin no#00 of IC3.

S"iente"# Te"#nologies !vt. Lt$. ''


34/90

ST2651

C!ec pin no#0 of IC3. it s!ould be 6#0@ appro2# >if not t!en IC may befaulty? if + t!en,

C!ec t!is volta"e at G terminal# If it is not t!en

T!ere may be trac open between pin no#0 of IC3.AG terminal %emove t!e s!ortin" s!unt from pin 0A7 and place it between .A0 of umper

B03, if it is not proper#

%emove t!e s!ortin" s!unt from pin 0A7 and place it between .A0 of umperB07#

%esult / Proper picture wit! sound is observed#=perient 10

O%,e"tive >To stu$3 t#e $etaile$ "ir"uit $es"ription o& 8ori?ontal Os"illator Se"tion an$

8ori?ontal Output Se"tions.

8ori?ontal Os"illator >

Pin no##1 of IC3. >C5689? supplies t!e composite sync si"nal to pin no#76 >Sync

Separator? of t!is IC t!rou"! t!e circuit of %7. >63?, %70 >38?, capacitor

C7. >.:?, C70 >#.:?, C77 >38P:? %3.7 >.3? and diode 57. >I41.19?#

Sync separator section separates t!e !ori7P:? and @%13. >.?# T!is tuned circuit is connected wit! pin

no#71 of IC689# +n varyin" t!e !ori8%0, 0$?,

519 >=.3? and passed t!rou"! %7 >77? and diode 5. >I41.19? and obtained at

pin no#77 of t!is IC# Pin no#7 and 7. are t!e ne"ative supply pins w!ic! are

"rounded#

8ori?ontal :river >

IC3. "ives t!e )ori


35/90

ST2651

to t!e primary coil of !ori

T!is section includes one transistor and E)T transformer# :rom secondary of

!ori


36/90

ST2651

ig. 11



37/90

ST2651

=perient 11

O%,e"tive >

To stu$3 t#e #ori?ontal os"illator an$ #ori?ontal output se"tion t#roug#olloing test points >

T!5 @e$ )oriappro2?

T!6 @e$ )oriappro2?

for @I: Section

T!) @e$ )oriappro2?

for %-G-= video output section

>C%T base PC=?

T!* @e$ )ori


38/90

ST2651

T!'5 @e$ )ori


39/90

ST2651

!ro"e$ure >

C!ec fly bac pulse of frequency .3803)< at pin no#73 of IC3. >IC689? if

not t!en, C!ec t!is fly bac pulse at resistance %10 >06o!m? if it is not t!en,

Trac may be open between pin no#. of E)T and t!is resistance#

%emove t!e s!ortin" s!unt from pin 0A7 and place it between .A0 of

umper B..#

%esult / now you s!ould "et fly bac pulse of frequency .3,803)< at pin no#73

of IC3. and so t!ere is "ood picture wit! "ood sound is observed#

ault 22 > :ar- S"reen7 ;4eit#er @aster nor sno< 4o soun$

ault Insertion >%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7of umper B.0#

S3ptos >T!ere is no picture no sound condition even raster or snow are also

absent#

ault se"tion >)oriIC689? it s!ould be 8#@ appro2#

C!ec pin no#70 of IC3. it s!ould be .3803)< >)ori


40/90


41/90

ST2651

ault 25 > :ar- S"reen H OG Soun$

ault Insertion >%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7

of umper B.3

S3ptos > Power indicators are "lowin" A all volta"es are +, but 4o picture

sound# is +#

ault Se"tion > )ori..@ 5C appro2?# If it is + t!en,

C!ec t!e volta"e at TP71 >9@ appro2?# If it is + t!en, C!ec t!e volta"e at TP6 >.93@ 5C appro2?# If it is + t!en, If t!e above mentioned volta"es are present, t!en E)T is worin" properly#

C!ec t!e filament volta"e at TP9 >8#7@ *C appro2?# If it is present#

Eit!er C%T may be faulty or t!e connection between C%T >Pin no#? A TP9 isopen#

%emove t!e s!ortin" s!unt between 0A7 A connect it between .A0 of umperB.3#

%esult / 4ow you s!ould "et %asterDsnow and sound#ault 26 > :ar- S"reen#


of umper B.7

S3ptos > Power indicator is "lowin", but no picture A no transmittin" sound#

ault Se"tion > )oriappro2? if it is + t!en,

C!ec t!e volta"e at TP3 it s!ould be ..@ >appro2?, if it is not t!ere t!en#

C!ec t!e volta"e at TP71 9@ appro2 if it is not present t!en, It means !ori 4egative t3pe pi"ture ;$ull pi"ture%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7

of umper B.1

S"iente"# Te"#nologies !vt. Lt$. (1


42/90

ST2651

S3ptos > Picture wit!out contrast#

ault Se"tion > )ori Picture and sound +# =ut retrace line on t!e picture

ault Se"tion > )ori


43/90

ST2651

=perient 1'

O%,e"tive >

To stu$3 t#e $etail "ir"uit $es"ription o& verti"al os"illator an$ verti"al outputse"tion.

Verti"al Os"illator >

@ertical oscillator is also built in IC3. >C5689? A pin no# 01, 03, 08, 06, 09, 0 are

its connection pins#*s we !ave already studied t!at vertical sync si"nal is present at

pin no#78 after sync separation# T!e vertical sync si"nal from pin no#78 passes from

circuit networ of %71 >.?, %77 >7?, %73 >0#1? and capacitor C7. >#16:?

and obtained at pin no#09#

@ertical oscillator produces 3 )< frequency w!ic! is amplified inside t!e IC and

available at pin no#01 w!ic! is vertical driver pin# T!is vertical driver si"nal from pin

no#01 is fed to base of vertical driver transistor '77 >C000? by resistance %703>77?# Collector of t!is transistor provides amplified output w!ic! is supplied to

vertical output section for amplification#

Verti"al Output >

@ertical driver si"nal is "iven to t!e vertical output section# In vertical output section

two pus!-pull transistors are used# +ne is 4P4 transistor '78 >C067? and anot!er

one is P4P transistor '76 >*1?#

@ertical si"nal from t!e collector of vertical driver transistor '77 >C000? are fed to

t!e base of bot! vertical output transistors '78 and '76# Pin no#9 of E)T

transformer provides t!e positive supply to vertical output section# T!ere is appro2#78@ *C at pin no#9 of E)T transformer# It is rectified by %706 >., 0$? and diode

570 >=.3? and supplied to vertical output section by %733 >06%? and %7.6 >89

?# Capacitor C7.. >77:? is filter capacitor of t!is supply# *mplified si"nal after

amplification is obtained at common point of bot! t!e emitters of bot! vertical output

transistors '78A'76# T!is si"nal is fed to vertical yoe coil by capacitor C7.8

>77:?#+t!er end of vertical yoe coil is "rounded by resistance %707 >.%9, .$?#

T!e same end of vertical yoe coil provides t!e vertical feedbac to pin no#08 of

vertical oscillator section by C7.6 >1#6: D 87@? and %70.>.?

Verti"al 8eig#t Control >

*t pin no# 06 of IC3. >C5689? vertical !ei"!t control is connected# @%003 >16?is vertical !ei"!t adustment preset and from its centre point vertical linearity preset is

connected w!ic! is @%7.8 >.?#

S"iente"# Te"#nologies !vt. Lt$. ('


44/90

ST2651

ig. 16

S"iente"# Te"#nologies !vt. Lt$. ((


45/90

ST2651

=perient 1(

O%,e"tive >

To stu$3 t#e verti"al os"illator an$ verti"al output se"tion t#roug# &olloing testpoints >

T!11 @e$ @ertical +utput @ oe

T!12 @e$ @ertical +utput @ oe

T!'2 @e$ @ertical oscillator @ertical feedbac

Part of video A C!roma IC

ig. 1)

T!'' lue @ertical +scillator @ertical driver

Part of @ideo A C!roma IC

ig. 1*

T!(1 @e$ @ertical output section .6 @ >appro2#?



46/90

ST2651

=perient 15

O%,e"tive >

To stu$3 t#e &ault siulation an$ step %3 step &ault &in$ing pro"e$ure o& verti"alOs"illator an$ verti"al output se"tion.

ault 2+ > T!ere is )ori%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7

of umper B.9

S3ptos >4o picture + sound# +nly )ori

C!ec vertical frequency of 3 )< at pin no#01 of IC3. >IC689? if it is +

t!en,

If it is not t!en IC or related circuit may be faulty

C!ec t!is si"nal at base of transistor '77, if it is not t!en

:aulty %703 or trac may be open between pin no#01 of IC3. and base of

'77#

%emove t!e s!ortin" s!unt from pin 0A7 and place it between .A0 of

umper B.9#

%esult / 4ow you s!ould "et picture on t!e screen#

ault '0 >=ottom fold over t!e picture on t!e screen#

ault Insertion >%emove t!e s!ortin" s!unt from pin 0A7 and place it between .A0

of umper B.6

S3ptos >T!e H of picture screen is + only bottom side .H picture is folded

over on t!e ori"inal picture#

ault Se"tion >@ertical output Section#

!ro"e$ure >

C!ec output of t!e vertical driver pin no#01 of IC3. It is vertical frequency of

3 ).%?# It s!ould be amplified

si"nal# It is not correct t!en,

:aulty components in its circuit or "round may be open#

C!ec %7.7 >.3? and its "round connection#

%emove t!e s!ortin" s!unt from pin .A0 and connect it between 0A7 of

umper B.6#

%esult / 4ow you s!ould "et clear picture#



47/90

ST2651

=perient 16

O%,e"tive >

To stu$3 t#e $etail "ir"uit $es"ription o& @E Vi$eo output Se"tion.T!e %-G-= output section mainly uses t!ree transistors# :irst one is '36 >C07.? for

red colour output# Second one is '39 >C07.? for "reen colour output and t!ird one

is '3 >C07.? used for blue colour output# %ed colour si"nal produced from pin no#

0. of IC3. >C5689? and fed to t!e base of transistor '36# *mplified si"nal from

t!is transistor are "iven to t!e red cat!ode pin no#9 of picture tube by resistance

%. >1#6?#

Green colour si"nal from pin no#0 of IC3. are fed to t!e base of transistor '39

from w!ere it is amplified and comes out from its collector# T!is amplified "reen

colour si"nal is "iven so t!e "reen cat!ode pin no 8 of picture tube by resistance %0

>1#6? In t!e same way blue colour si"nal from pin no#00 of IC3. are fed to t!e baseof transistor '3 amplified si"nals are obtained at its collector from w!ere t!e si"nal

is "iven to t!e blue cat!ode pin no#.. of picture tube by resistance %7# >1#6?

Collectors of all t!e t!ree output transistors "ets t!e .93@ supply from pin no#0 of

E)T transformer# %ed colour output transistor '36 "ets it by resistance %3. >.3

0$? "reen colour output transistor '39 "ets it by resistance %30 >.3 0$? and

blue colour output transistor "ets t!is supply by resistance %37 >.3 0$? Green

colour and blue colour output transistor !as 00preset connected wit! t!eir emitters

for proper ali"nment of colour on screen, actually by doin" t!is we are c!an"in" t!e

amplification of transistors#

S"iente"# Te"#nologies !vt. Lt$. ()


48/90

ST2651

ig. 1+

S"iente"# Te"#nologies !vt. Lt$. (*


49/90

ST2651

=perient 1)

O%,e"tive >

To stu$3 t#e $etail "ir"uit $es"ription o& soun$ output se"tion.S"iente"# colour T@ trainer ST2651uses most commonly used sound amplifier

ICT5* 08..# In our circuit it is IC8.# *s we !ave already studied t!at audio si"nals

are available at pin no#7 of IC.. >C5689?-w!ic! is supplied to base of audio

amplifier transistor '8. >0S* ..3? by capacitor C89 >.:D87@? %esistance %S.

>.?, %.0 >0#0?# Collector of transistor '8. >03*..3? "ives amplified si"nals#

T!is amplified si"nal is fed to pin no#6 of sound output by resistance %83* >1#6?

and C83 >#.:?#*udio si"nals are amplified up to t!e sufficient level by t!is IC and

obtained at pin no#0 of t!is IC#

It is provided to speaer by a capacitor C8. >16:, .8@?, pin no#. of IC8. is

positive supply pin# S&PS transformer in power supply section provides *C volta"efrom pin no#0 w!ic! is rectified by diode 59. >=.3? 00@ appro2# volta"e is

obtained w!ic! is "iven to pin no#. of IC.8. >T5*08..?#Pin no#1 of IC8. is

"rounded# +t!er pins 7, 3 and are no contact pins or not connected pins#

=perient 1*

O%,e"tive >

To stu$3 t#e &ault siulation an$ step %3 step &ault &in$ing pro"e$ure o& Soun$

Output Se"tion.

ault '1 >T!ere is no sound from speaer#

ault Insertion >%emove t!e s!ortin" s!unt from pin 0A7 and place it between .A0of umper B

S3ptos >Good Picture on t!e screen but wit!out sound#

ault Se"tion >Sound Section#

!ro"e$ure >

C!ec power supply 0@ at pin no#. of IC8. >IC08..? if it is + t!en,

C!ec audio input si"nal at pin no#6 of IC8. it s!ould be low "ain audio

si"nal# If it is + t!en,

C!ec audio output si"nal at pin no#0 of IC8. it s!ould be amplified audiosi"nal# If it is + t!en,

If it is not t!en IC may be faulty

C!ec t!is amplified audio si"nal at speaer pin >connected wit! speaer?

If it is not t!en trac may be open between IC8. >pin no#0? and speaer pin, if

it is + t!en speaer may be faulty#

%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7 of

umper B#

%esult / 4ow you s!ould "et >sound? audio si"nal from speaer#

S"iente"# Te"#nologies !vt. Lt$. (+


50/90

ST2651

ault '2 > 4o soun$ %ut goo$ pi"ture#


of umper B.S3ptos > Sound is not present but "ood picture#

ault Se"tion > Sound section#

!ro"e$ure >

:irst c!ec t!e speaer, if it is + t!en,

C!ec t!e volta"e of IC8. at Pin no#. it s!ould be 0@ appro2, if it is notpresent t!en,

C!ec t!e volta"e of 59. it s!ould be 0@ appro2# If it is + t!en,

C!ec t!e continuity of trac between 59.A IC8. at pin no#. if no continuitypresent t!en,

%emove t!e s!ortin" s!unt between .A0 connect it 0A7 of umper B.# %esult / 4ow you s!ould "et sound#ault '' > Ver3 lo soun$. ut o- pi"ture#


of umper B9

S3ptos > Sound is not varyin" by t!e volume control but + picture#

ault Se"tion > Sound section#

!ro"e$ure >

:irst c!ec t!e audio at t!e base of '8. by touc!in" any metallic t!in" lie

screw driver#

C!ec t!e SI: si"nal of IC.. at Pin no#7, if it is +, t!en C!ec SI: si"nal at =ase of transistor '8., if it is not t!en Transistor may be faulty or trac may be open between Pin no#7 of IC.. and

=ase of Transistor '8.

%emove t!e s!ortin" s!unt between .A0 and connect it 0A7 umper B9 %esult / 4ow you s!ould "et volume variation#



51/90

ST2651

=perient 1+

O%,e"tive >

To stu$3 t#e $etail "ir"uit $es"ription o& AV se"tion.*@ section is used for !earin" audio si"nals or watc!in" t!e video si"nals from

e2ternal source lie @C% or @C5 or 5@5 #C5 players available in maret mostly

supply *udio-@ideo output si"nals t!at can be seenD!ear only on t!at television set

w!ic! !ave t!e facility of *@ section# If t!e television set does not !ave t!is facility

t!en t!ere is need of conversion of *@ si"nal to %: si"nals wit! t!e !elp of converter#

:or usin" *@ facility we !ave to press *@ switc! on remote# T!ere will be plane

raster on t!e screen and *@Q will be displayed on t!e screen# It means trainer is now

ready to accept input si"nals from *@ socet and !ence t!e %: si"nals present on %:

input socet from antenna are disconnected#

Pin no#1of IC. >System Control Section? provides *@ si"nals at t!e base oftransistor '60 >CI9.3D=C316? by a diode 561 >I41.19? as t!e transistor "ets t!e

si"nal on its base it starts conductin" and !ence t!ere is ne"ative volta"e on collector

of t!e transistor# T!is ne"ative volta"e is fed to pin no#0.of IC.. >C5689? by diode

560 >I41.19?# It is input pin of sound I:#T!is volta"e stops t!e sound I: si"nals

entry at IC So in *@ mode t!ere is no# In t!e same way t!is ne"ative volta"e is also

fed to t!e pin no 3 of IC689 by a diode 567 >I41.19? t!is pin is video amplifiers

pin due to t!is volta"e video si"nals are unable to "o in forward sections, so on

selectin" *@ mode t!ere is plane raster on t!e screen wit! sound mute#

4ow on connectin" @C%D@C5 *@ input socets t!e si"nals from @C%D@C5 can be

seen on t!e screen#Vi$eo Signals I4 >

@ideo si"nal obtained from @C%D@C5 is fed to t!e base of video si"nal amplifier

transistor '63 >C.9.3? by a capacitor C66 >16fd? and diode 563 >I41.19?#

*mplified si"nals come out from its emitter and are provided to T%*P >3#3&)


52/90

ST2651

ig. 20



53/90

ST2651

=perient 20

O%,e"tive >

To stu$3 t#e &ault siulation an$ step %3 step &ault &in$ing pro"e$ure o& AVSe"tion.

ault '( > 4o soun$ in AV Mo$e ut goo$ pi"ture#


of umper B7

S3ptos > Si"nal fed in audioDvideo socet from @C%D@C5 is +, but no sound#

ault Se"tion > *@ section

!ro"e$ure >

C!ec t!e cable connectivity between @C%D@C5 and input socet of T@

trainer# If it is + t!en,

C!ec t!e sound si"nal comin" from @C%D@C5 by oscilloscope# C!ec t!e audio si"nal at t!e base of '60, if not

T!en t!e capacitor C67 >#.3R:? may be faulty or trac may be open between

capacitor A t!e transistor base#

%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7 of umper#B7

%esult / 4ow you s!ould "et soundault '5 > Vi$eo is not "oing %ut proper soun$.


of umper B0

S3ptos >Si"nal fed in audioDvideo socet from @C%D@C5 is +, but no picture#

ault Se"tion > *@ Section#

!ro"e$ure >

C!ec t!e cable connectivity between @C%D@C5 and input socet of T@ trainer

C!ec t!e video si"nal comin" from @C%D@C5 by oscilloscope

C!ec t!is si"nal at base of transistor '63, if it is + t!en C!ec @ideo si"nal at %esistor %39, if it is not present t!en, Transistor may be faulty or trac may be open between %39 and =ase of

transistor '63#

%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7 of umperB0#

%esult/ 4ow you s!ould "et picture#



54/90

ST2651

ault '6 >9#ile sele"ting AV o$e plane raster it# ute soun$ #i"# s#oul$

%e t#ere is not present.

ault Insertion >%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7of umper B7

S3ptos >Snow added picture is observed on t!e screen

ault Se"tion > *@ Section

!ro"e$ure >

Select t!e Trainer in *@ mode#

C!ec t!e volta"e of IC. at pin no#1#It s!ould be .#9@ appro2# If t!e presentvolta"e observed is 3@ appro2#

Proper volta"e #83@ appro2 s!ould be present on pin no#3 A pin no#0. ofIC..#If not,

5iode 560D67 may be faulty# If not, C!ec t!e continuity between 561 A IC. >Pin no#1?# If continuity is not

present t!en,

%emove t!e s!ortin" s!unt from 0A7 and connect it between .A0 of umperB7#

%esult /Plain, raster A mute sound is obtained# in *@ mode



55/90

ST2651

=perient 21

O%,e"tive >

To stu$3 t#e $etail "ir"uit $es"ription o& S3ste Control Se"tion.S"iente"# "olour TV trainer ST2651uses IC. :+45*1ST for system control

purpose# It is dual in line paca"e 1 pin IC w!ic! controls all t!e sections of t!e T@

Trainer# Pin no#., 0 and 7 are band switc!in" pins# .stpin is used for switc!in" t!e @L

band# Second one is used to switc! @) band and t!ird pin is for (): band Pin no#1

provides T@D*@ switc!in" si"nals on pressin" t!e *@ switc! from remote control,

t!e %: si"nals comin" from antenna or cable are disconnected wit! @I: section#

)ence t!ere is only raster on t!e screen wit!out snow# Pin no#3, 8, 6, 0., and 00 are

t!e ey matri2 pins, w!ic! are connected wit! eyboard# eyboard is used for

selectin" one function from front panel# Pins 9A are t!e on screen display oscillator

pins# )orisi"nals? play an importantrole for "ettin" +4 screen display >+S5? on t!e screen# T!e coil connected on pin no#

9A decides t!e frequency of Internal +scillator# T!ese !ori=C339=?# *fter amplification from t!is transistor t!ese si"nals are

fed to t!e base of ot!er +S5 blanin" driver transistor '9 >=C339=?# :rom w!ere

t!e si"nals are out from its collector and fed to t!e base of luminance amplifier

transistor '00 >0S* ..3?#

Pin no#7 is output pin of "reen +S5 si"nals# T!e si"nals from t!is pin are fed to base

of "reen +S5 driver transistor '8 >=C316=? and t!en to t!e base of "reen +S5

output transistor '. >0SC.9.3?# T!e output of t!is transistor is fed to t!e emitter of

>G-drive? "reen colour output transistor '39 >C07.?#



56/90

ST2651

Pin no#7. is output pin of red +S5 si"nal# T!ese red +S5 si"nals are fed to t!e base

of red +S5 driver transistor '3 >=C316=?# *fter amplification t!ese si"nals are

fed to red +S5 output transistor '0 >0SC.9.3? from emitter of previous transistor#

T!e amplified si"nals are obtained at collector of '0 and are "iven to t!e emitter ofred output transistor '36 >C07.?# Pin no#77 is tunin" pulse output pin t!e si"nal

from t!is pin switc!es +4 t!e tunin" pulse switc!in" transistor to "et t!e -77@ at

T@ terminal#

Pin no#71 is Infrared remote input pin +4 pressin" t!e remote switc!es# T!e si"nals

are obtained first at t!is pin for any function from remote switc!O remote provides

infra red waves, w!ic! falls on sensor EE on front panel# T!is eye reco"ni689?# Pin no#76 is contrast control pin# T!e

contrast control si"nals are fed to pin 1. of IC689# Pin no#79 is bri"!tness controlpin# T!e si"nals from t!is pin are fed to pin no#1 of IC689#

Pin no#7 is volume control pin# T!e volume control si"nals from t!is pin are supplied

at t!e base of transistor '. >=C316 - @olume Control Transistor?# T!e si"nals from

t!e collector of t!is transistor are "iven to t!e si"nal input pin no#. of IC689# Pin

no#1 is 3@ supply pin# +utput of IC.0 >L693? is directly connected on t!is pin#

Pin .8, ., 0 are "round pins# Pin no#.6, .9, 07 are =ias pins# T!e =iasin" is

provided from 3@ supply# Pin no#70A73 are no connection pins#



57/90

ST2651

ig. 21



58/90

ST2651

=perient 22

O%,e"tive >

To stu$3 t#e s3ste "ontrol se"tion t#roug# &olloing test points.T!2( lue .9@ >appro2?

T!25 @e$ 3@ >appro2?

T!(2 @e$ System Control Section @ appro2# from system control IC to

select @): I band >@L? ot!erwise @#

T!(' @e$ System control Section @ w!en @): III >@)? band selected

ot!erwise @ appro2#

T!(( @e$ System control Section @ w!en (): band selected ot!erwise

@ appro2#

T!(5 lue System Control Section )ori


59/90

ST2651

T!() lue System Control Section Input for *:T 7#0 @5C

>appro2?

T!(* lue System Control Section Ident si"nal #0-3 @5C>appro2?

T!(+ @e$ System Control Section Input pin for standby

&ode 3@ w!en power is +4

ot!erwise @

T!50 @e$ System Control Section +utput of tunin" si"nal

3@pp appro2#

T!51 lue System Control Section 3@ appro2# Infrared si"nal from

%emote

T!52 @e$ System Control Section Colour control pin #0-9@

appro2#

>&iddle position of colour control?

ig. 2(

T!5' @e$ System Control Section Contrast control pin 8-.@

appro2

>&iddle position of contrast control?

ig. 25



60/90

ST2651

T!5( @e$ System Control Section =ri"!tness control pin #1 - @

appro2#

>&iddle position of =ri"!tness control?

ig. 26

T!55 @e$ System Control Section @olume control pin #0 - 1@

appro2

>&iddle position of @olume control?

ig. 2)



61/90


62/90

ST2651

%emove t!e s!ortin" s!unt from pin 0A7 and place it between .A0 of umper

B77#

%esult / 4ow you s!ould "et volume variation w!en operated#ault '+ > @eote "ontrol is not or-ing.


of umper B71

S3ptos > %emote control functionin"Dworin" is totally +::

ault se"tion > System control section

!ro"e$ure >

C!ec I%>Infrared ?si"nal 3@ appro2# at TP3., if it is not t!en

C!ec t!e same I% si"nal at I% terminal >=er" strip? if it is + t!en

Trac may be open between I% terminal and TP3.

%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7 of umper

B71#

%esult / 4ow remote control can be used

ault (0 > 4o "ontrast Variation


of umper B73

S3ptos >Contrast variation is not worin"#

ault se"tion > S3ste "ontrol se"tion

!ro"e$ure >

C!ec pin no#76 >contrast control pin? of IC. >:onda 1ST? 4ow, if you vary

t!e contrast from remote t!e volta"e at t!is point s!ould vary from - 8m@ to

0#.@ appro2, if it is + t!en

C!ec pin no#1. of IC3. >IC689? A vary t!e contrast from remote you s!ould

"et appro2# .@ variation from its present volta"e# If it is not t!en

Trac may be open between pin no#76 of IC. and pin no#1. of IC3. %emove s!ortin" s!unt from pin .A0 and place it between 0A7 of umper

B73

%esult / 4ow you s!ould "et contrast variation

ault (1 > 4o rig#tness variation


of umper B78

S3ptos >4o variation in bri"!tness but "ood picture A sound#



63/90

ST2651

ault se"tion > System control section

!ro"e$ure >

C!ec pin 79 of IC. >:onda 1ST? w!ile varyin" t!e bri"!tness !ere volta"evaries from .#m@ to 0#8@ appro2# If it is + t!en

C!ec pin 1. of IC3. >IC689? and vary t!e bri"!tness you s!ould "et t!e

volta"e variation from 6#7 to 8#@ appro2# if it is not t!en

Trac may be open between pin 1. of IC3. and pin 79 of IC.#

%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7 of umper

B78#

%esult / 4ow you s!ould "et bri"!tness variation#

ault (2 >Trainer is :ea$.ault Insertion >%emove t!e s!ortin" s!unt from pin .A0 and place it between 0A7

of umper B17

S3ptos >4o picture, 4o sound and no power indication #

ault Se"tion >System control section#

!ro"e$ure >

:irst c!ec t!e *C mains supply, if it is connected properly t!en

C!ec t!e volta"e at TP01 .@ appro2, if it is not t!en C!ec t!e volta"e at TP03 3@ appro2 ,if it is not present t!en C!ec t!e same volta"e at %9 >.3%? if it is not + t!en C!ec t!e continuity of trac between TP01A%9 >.3E?# If no continuity is

present

%emove t!e s!ortin" s!unt between 0A7 connect it between .A0 of umper B17# %esult / 4ow proper picture wit! sound is observed#ault (' >Trainer is $ea$


of umper B1.

S3ptos >4o picture, 4o sound and no power indication

ault Se"tion >System control section#

!ro"e$ure >

:irst c!ec t!e *C mains supply, if it is + t!en

C!ec t!e volta"e at TP01 .@ appro2, if it is + t!en C!ec t!e volta"e at TP03 3@ appro2, if it is + t!en



64/90

ST2651

C!ec t!e same volta"e 3@ appro2 of IC at pin no#1, If it is not presentt!en

C!ec t!e continuity of trac between TP03Apin no#1 of IC.#If nocontinuity is present t!en

%emove t!e s!ortin" s!unt between .A0 connect it between 0A7 of umper B1.# %esult / 4ow proper picture wit! sound is observed#ault (( >Ver3 lo soun$.

ault Insertion >%emove t!e s!ortin" s!unt from pin .A0 and place it between . A

0 of umper B79

S3ptos >4o variation in sound

ault Se"tion > System control Section#!ro"e$ure >

C!ec t!e volta"e variation at t!e collector of t!e transistor '.# It will be

between 7#.@ to 1#8@ appro2# If t!is variation of volta"e is not present t!en

C!ec t!e volta"e at TP33 w!ile varyin" t!e volume control# @ariation ofvolta"e level is noticed between .6 m@ A 1#8@ but still t!ere is no c!an"e in

sound t!en,

C!ec t!e continuity of trac between TP33A'. >=C316?# If continuity isnot present t!en

%emove t!e s!ortin" s!unt between 0A7 and connect it between .A0 of umperB79#

%esult/ 4ow you s!ould "et "ood, full sound A full volume variation#ault (5 > Trainer is $ea$.


of umper B11

S3ptos >4o picture, 4o sound, but power indication is "lowin"#

ault Se"tion > System control Section#

!ro"e$ure >

:irst c!ec t!e volta"e at TP03, 3@ appro2 s!ould be obtained# If it is + t!en

C!ec t!e volta"e of IC. at pin no#1, 3@ appro2 s!ould be obtained# If it is+ t!en

C!ec t!e volta"e drop at t!e diode 51, It s!ould be 7#9@ >appro2?# If not,5iode may be faulty# If t!e diode is proper t!en

T!ere is a possibility of t!e resistance %63 to be open# If it is not so t!en,



65/90

ST2651

C!ec t!e continuity of trac between %63>16%?A51>7@9? If continuity isnot present t!en,

%emove t!e s!ortin" s!unt between 0A7 connect it between .A0 of umper B11#

%esult / 4ow "ood picture A sound is observedault (6 > Meor3Store pro%le#


of umper B1

S3ptos >#&emory stora"e function >Lan"ua"e selection mode etc?#


!ro"e$ure >

T!e components connected between IC. A IC0 may be faulty# If it is +#+ne or bot! t!e ICs may also be faulty, if it is not proper t!en

C!ec t!e continuity of trac between IC. pin no#..-.0AIC0 pin no#3-8# Ifit is not present t!en

%emove t!e s!ortin" s!unt between .A0 and connect it between 0A7 of umperB1#

%esult / 4ow memory stora"e functions will functionault () > Auto tuning is not possi%le#

ault Insertion >%emove t!e s!ortin" s!unt from pin 0A7 and place it between .A0of umper B13

S3ptos > Tunin" will not wor properly in *uto &ode >*:T si"nal not present?


!ro"e$ure >

C!ec t!e volta"e of IC.. at pin 4o#.7#If it is 8@ appro2 t!en

C!ec t!e volta"e at t!e base of transistor '.*# It s!ould be 8@ appro2# If itis not present# Transistor is faulty or else,

T!e components are faulty A no continuity of trac between '.* >=ase? andIC.. and pin no .7

%emove t!e s!ortin" s!unt between .A0 and connect it between 0A7 of umperB13#

%esult / 4ow tunin" will function properly and picture is obtained#ault (* > OS: is not present#


of umper B10

S3ptos >Picture A sound + but not "ettin" +S5#



66/90

ST2651


!ro"e$ure >

C!ec t!e vertical =lanin" pulse at TP18 ,if it is + t!en

C!ec t!e )ori


67/90

ST2651

=perient 2(

O%,e"tive >

To stu$3 t#e $etail "ir"uit $es"ription o& Sit"#e$ Mo$e !oer Suppl3 ;SM!S0#0D.$? is called floatin" "round#

T!is floatin" "round is connected wit! main c!assis "round by a resistance %90

>.&D#3$?# T!ere is .3 @5C on floatin" "round wit! respect to main "round# In

t!e same way t!ere is appro2#7 @5C at positive point of brid"e wit! respect to

floatin" "round# 5ue to t!is t!ere is 13 @5C volta"e at positive of brid"e wit!

respect to c!assis "round# So w!ile testin" S&PS section we !ave to always connect

ne"ative of multimeter wit! floatin" "round and for testin" of ot!er circuits main

"round is used#

4ote >4ever s!ort floatin" "round wit! main c!assis "round, it may dama"e t!e

circuit#

T!e Power Supply section uses 1 transistors in t!e circuit

Transistor '9. >C.9.3? - Error 5etector

Transistor '90 >0S*..3? - Error 5river - .

Transistor '97 >C.9.3? - Error 5river - 0

Transistor '91 >=539*:? - Switc!in" Transistor

'90 and '97 are used to control t!e duty cycle of '91# =ot! t!ese transistors are

worin" as complimentary transistors and "et t!e required supply from pin no#9 of

S&PS transformer for functionin"# *ccordin" to output volta"e at secondary of

S&PS transformer '9. is used to c!an"e t!e duty cycle# Fener diode 59.. >9#0@? isused to stabili


68/90


69/90

ST2651

ig. 2*



70/90

ST2651

Elossar3

ACC >*utomatic colour control#

Aperture Mas- > * metal plate wit! framed !oles, placed closely be!ind t!ep!osp!or dot coated screen in a colour T#@# picture tube# Its function is to ensure t!at

eac! of t!e t!ree electron beams stries only t!e desired colour p!osp!or dot

associated wit! t!e beam# T!is is also nown as s!adow beam#

Aspe"t @atio >%atio of t!e widt! to !ei"!t of picture frame#

A"tive Lines >T!e television ima"e lines actually visible on screen of picture are

803# +ut of t!ese 393 are active, t!e remainin" occur durin" t!e vertical retrace

period, w!en t!e viewin" tube is blaned out#

A/ua$ag Coating >It is t!e conductive "rap!ite coatin" on inside "lass wall of t!e

picture tube funnel or bell, t!at e2tends from face plate or screen to about !alfway

into t!e narrow nec# T!is coatin" acts as final anode#

AT >*utomatic fine tunin" - an arran"ement used in colour T#@# receivers to

automatically c!ec and correct t!e frequency of t!e local oscillator in t!e tuner# T!is

ensures t!at t!e video I: remains at t!e correct value and eliminates t!e need of

frequent adustment of t!e manual fine tunin" control#

AEC >* circuit arran"ement, w!ic! adusts t!e "ain of t!e receiver and eeps t!e

output relatively constant, in spite of variation in stren"t! of input at aerial#

alun >*n impedance matc!in" device for antennas used between transmissions#

ar Eenerator >* "enerator for producin" pulses equally separated in time t!at are

sync!roniT!e process of applyin" ne"ative volta"e to t!e control "rid of C%T to cut

off t!e electron beam durin" t!e retrace or fly bac period#

oost Suppl3 >* !i"! volta"e 5#C# supply produced in a !ori9 to . cycles of t!e sub carrier are transmitted in t!e bac porc! of t!e

!ori


71/90

ST2651

Carona >* point at !i"! potential can ioni* colour term definin" t!e !ue and saturation of a colour#

C#roinan"e Signal >T!e ( and @ sidebands of t!e modulated colour sub carrier#

T!ese carry information pertainin" to t!e !ue and saturation of t!e colour but no

information re"ardin" t!e bri"!tness#

C#o-e Coil >It limits t!e flow of alternatin" current w!ile allowin" direct current to

pass#

Colour urst >* sync!roniComposite colour video si"nal or composite video si"nal in colour T@

receivers# T!is includes t!e luminance si"nals, coded c!roma si"nals, sync si"nals and

t!e colour sub carrier burst# #

Copleentr3 Colour >* colour formed by subtractin" a sample colour from w!ite

li"!t# :or e2ample if red is subtracted leavin" "reen and blue t!e complementary

colour is cyan#

Convergen"e >T!e cross over of t!e t!ree electron beams of t!e t!ree "un tricolour

picture tube# T!is occurs at t!e plane of t!e aperture mas#

C#roa :ela3 Line :e"o$er >T!e (A@ si"nals are transmitted on a sin"le sub

carrier# T!is is nown as quadrature modulation# T!e function of c!roma delay line

decoder is to separate t!e modulated (A@ components from t!e quadrate modulated

si"nals# T!is decoder utiliColour iller is used to bloc t!e c!roma amplifier on blac and

w!ite transmission# T!is is controlled by t!e colour burst si"nal and on blac and

w!ite transmission, w!en t!e colour burst is absent it biases t!e c!roma amplifier cut

off# T!us it prevents any spurious si"nals "ettin" t!rou"! t!e c!roma section w!ic!

can cause co loured snow on t!e picture tube screen#

S"iente"# Te"#nologies !vt. Lt$. )1


72/90

ST2651

:ela3 Line >* time delay device consistin" of an actual or artificial transmission

line, its purpose in colour T@ receivers is to ensure t!e coincidence of t!e

luminance>? and t!e c!rominance >( and @? si"nals#

:e&le"tion o-e >*n assembly of one or more electroma"nets to produce deflections

one or more electron beams#

:ete"tion >Sta"e in w!ic! demodulation or detection tae place#

:ropping @esistan"e >* resistor used to decrease t!e volta"e in a circuit#

:aper :io$e > 5amper diode conducts immediately after !ori5amper diode is also called efficiency diode, because w!en it is

conductin" it provides !oriIn television si"nals t!e two pulse trains of 8 pulses eac! w!ic!

occur ust before and ust after a vertical sync!roni T!e complete picture or scene to be scanned is called frame it consists of 803

!ori In a test pattern a scale t!at illustrates uniform c!an"es in si"nal

amplitude from w!ite, pro"ressin" t!rou"! "ray values in equal steps to blac#

8u >* low audio frequency, !avin" t!e same frequency as t!at of t!e power supply

or a !armonic t!ere of introduced, into t!e si"nal pat!s by inductions, leaa"e or

insufficient filterin" and !eard in t!e bac "round or a received radio pro"rammer or

appearin" across a television ima"e in t!e form or one or two !oriT!e dominant wavelen"t! of li"!t representin" t!e colour of an obect# It is t!eredness, blueness or "reenness of an obect#

83%ri$ @e"eiver > In t!is type, t!e deflection circuits "enerally use power tubes,

w!ile t!e si"nal circuit use transistors and ICs# T!ese receivers usually !ave filaments

connected in series c!ain#

8ol$ Control >* T@ receiver !as vertical !old control# T!e vertical !old control

adust t!e frequency of t!e vertical oscillator close enou"! to 3 )< so t!at is loced

by incomin" sync pulses#

Ignition Inter&eren"e > Interference produced by auto i"nition spars or ot!er

i"nition disc!ar"es#

S"iente"# Te"#nologies !vt. Lt$. )2


73/90

ST2651

Iage > * reproduction of a person, obect or scene suc! as t!at produced by a

television receiver#

Ipregnate > To treat component so as to mae it moisture resistance by fillin" t!ee2cess space in its container wit! a material suc! as a wa2 or pitc!#

In&ra la"- @egion > T!e portion of t!e video si"nal above t!e blac level# It

contains t!e sync!roniT!e %: sound carrier is 3#3&)< above t!e picture carrier# *ll

television receivers use 3#3&)< as frequency of sound I: si"nal# T!is 3#3&)< si"nal

is called t!e inter carrier sound carrier at 77#1&)< wit! picture carrier at 79#1&)< in

video detector#

Interla"e$ S"anning >In television, a system in w!ic! even lines of t!e ima"e are

scanned durin" one downward sweep of t!e scannin" beam and remainin" odd frames

are scanned durin" t!e ne2t downward sweep of t!e scannin" beam#

Bitter >5istortion in received television or facsimile picture caused by momentary

errors in sync!roniT!e *GC circuit employin" fly bac pulses from !oriIn monoc!rome television, a si"nal wave for controllin" t!eluminance values in t!e picture#

Multi%an$ Antenna >*n antenna t!at can be used wit! satisfactory results on a

number of frequency bands#

Matri >&atri2 sub section consists of amplifier sta"es alon" wit! volta"e combinin"

and dividin" networs# T!is section obtains bac t!e primary colour si"nals from t!e

c!roma si"nals and t!e luminance si"nals "iven to it# T!e primary colour si"nals %,

G, =, obtained t!e matri2 section are "iven to t!e output video amplifiers circuit#

4atural re/uen"3 > In an un damped body or system, t!e frequency at w!ic!

oscillation will continue after t!e applied force !as been removed#

S"iente"# Te"#nologies !vt. Lt$. )'


74/90

ST2651

4oise Inverter >*lso called noise "ate, t!is circuit inverts t!e polarity of noise pulses

by reversin" t!e polarity of its video si"nal# T!e purpose is to cancel noise pulses in

t!e video si"nal to t!e *GC or sync separator sta"e#

Out o& S3n" > not sync!roniT!e picture !as reversed blac and w!ite values and is out of

sync# T!e picture is out of sync !oriP!ase *lteration by LineQ - T!is system is a refinement of t!e 4TSC system

and !as been adopted in our country# T!is system was developed in t!e federal

republic of Germany and introduced in .86#

In t!is system t!e t!ree colour si"nals i#e# %, G, =, si"nals obtained from t!e colour

camera are processed to obtain t!e luminance si"nal # T!e luminance and two coloursi"nals are combined to obtained ( and @ si"nals# T!ese si"nals are also quadrate

modulated on a colour sub carrier and t!e side bands are transmitted alon" wit! t!e

rest of t!e video si"nals# * specialty of t!is system is t!at one of t!e two colours

different si"nals namely @ si"nal is reversed in polarity durin" alternate lines#

!#ase S#i&t >*s t!e quadrate modulation is used for transmittin" t!e c!roma si"nals,

t!e sub carrier used for modulatin" t!e ( si"nal !as a de"ree p!ase s!ift for

demodulatin" t!e ( si"nal t!e p!ase of t!e sub carrier "iven to t!e ( demodulator

s!ould also !ave a de"ree p!ase s!ift# T!e p!ase s!ifter s!ifts t!e p!ase of t!e sub

carrier "iven to t!e ( demodulator by de"ree#

!urit3 Coil >*n electroma"netic device placed about t!e nec of a t!ree "un tricolour picture tube# Its function is to control t!e an"le at w!ic! t!e t!ree beams

approac! t!e aperture mas# Its correct adustment produces t!e pure colours of red,

"reen, and blue on t!e screen#

!urit3 Magnates >Two ma"neti* small coil placed in an amplifyin" circuit to increase response at

certain frequencies, specifically as resonated peain" coilsM used in a video amplifier

for !i"! frequency compensation in most cases !as resistor connected across#

!en"il ea >Emission, from an antenna !avin" t!e form of narrow conical beam#!i"ture =leent >In a television system, t!e smallest portion of a picture or scene

t!at is individually converted into an electrical si"nal#

!e$estal >T!e si"nal introduced into t!e comple2 video si"nal at or above t!e blac

level used to blan out video si"nals durin" retrace period#

!in"us#ion :istortion >If deflection is not uniform at t!e ed"es of raster, compared

wit! t!e centre# T!e raster will not !ave strai"!t ed"es, and if t!e scannin" lines are

bowed inwards t!is fault is called pincus!ion distortion#

S"iente"# Te"#nologies !vt. Lt$. )(


75/90

ST2651

Qua$rature Mo$ulation >* system for modulatin" two si"nals simultaneously on a

sin"le carrier enablin" simultaneous transmission of two si"nals# T!is met!od is used

in t!e 4TSC and P*L colour T@ system for transmittin" t!e two colour difference

si"nal# :or t!is t!e colour sub carriers split in two parts w!ic! differ by de"rees#+ne of t!ese modulated by t!e ( si"nal and t!e ot!er by @ si"nal# T!e two are t!en

combined providin" t!e quadrate modulated c!roma si"nal#

@aster >T!e illuminated rectan"ular area scanned by t!e electron beam in a picture

tube visible w!en t!e bri"!tness control is turned up wit! no si"nals#

@atio :ete"tor >*n :& detector t!at uses a pair of diodes connected in suc! a

manner t!at t!e audio output is proportional to t!e ratio of t!e :& volta"e applied to

t!e two diodes#

@everse Age >In t!is met!od, t!e transistor "ain is decreased by reducin" t!e forward

bias at t!e base toward cut off#@esonan"e >In a circuit containin" bot! inductance and capacitance a condition in

w!ic! t!e inductive reactance is equal to t!e capacitive reactance#

@e&eren"e la"- Level > T!e picture si"nal level correspondin" to specified

ma2imum limits for peas#

@ipple >*C component present in 5C power supply#

Saturation > 5e"ree to w!ic! a colour is pure undiluted wit! w!ite li"!t# * fully

saturated colour does not !ave any w!ite in it#

S3n"#ronous :eo$ulation > In a colour T@ receiver t!e process of separately

detectin" t!e ( and @ side bands of t!e c!roma si"nal# T!is requires t!e colour subcarrier alon" wit! t!e balanced demodulator#

S3n" Separator > Composite colour si"nal >CCS?available from video buffer in

c!roma section is "iven to t!e sync separator# It separates t!e composite sync from t!e

CCS si"nal# T!e !ori* "rid placed between t!e control "rid and t!e anode and usually

maintained at affi2ed positive potential#

Se"on$ Ano$e >T!e electrode in a cat!ode ray tube t!at is maintained at a constantpositive potential and used to accelerate electron beam#

Serrate$ !ulses >* series of equally spaced wit! in pulse si"nal# :or e2ample, t!e

vertical sync pulse is serrated in order to eep t!e !ori

colour tv trainer

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