Panasonic CT27C8G - 27" COLOR TV User manual

1. Safetyprecautions
General guidelines
Anisolation transformershouldalways beusedduring theservicing ofareceiverwhose chassis
isnotisolatedfrom ACpowerline. Use atransformerofadequatepowerrating as thisprotects
thetechnicianfrom accidentsresulting inpersonal injuryfrom electrical shocks. Itwill also
protectthereceiverfrom being damagedbyaccidental shorting thatmay occur during servicing.
Whenservicing, observe theoriginal leaddress, especiallyinthehigh voltagecircuit. Replace all
damagedparts(alsopartsthatshowsignsofoverheating.)
Always replace protective devices, suchas fishpaper, isolation resistorsand capacitors, and
shieldsafterservicing thereceiver. Use onlymanufacturer’srecommendedrating for fuses,
circuitsbreakers, etc.
High potentialsarepresentwhenthisreceiverisoperating. Operation ofthereceiverwithoutthe
rearcoverintroduces dangerfor electrical shock. Servicing shouldnotbeperformedbyanyone
who isnotthoroughlyfamiliarwiththenecessaryprecautionswhenservicing high voltage
equipment.
Extremecareshouldbepracticedwhenhandling thepicturetube. Rough handling may cause it
toimplodeduetoatmosphericpressure. (14.7lbspersq. in.). Donotnick or scratchtheglass or
subjectittoanyunduepressure. Whenhandling, usesafetygoggles and heavy gloves for
protection. Dischargethepicturetubebyshorting theanodetochassisground (nottothe
cabinetor toothermounting hardware). Whendischarging connectcoldground (i.e. dagground
lead)totheanodewithawellinsulatedwireor use agrounding probe.Avoidprolongedexposure
atclose rangetounshieldedareas ofthepicturetubetopreventexposuretoxray radiation.
Thetestpicturetubeusedfor servicing thechassisatthebenchshouldincorporatesafetyglass
and magneticshielding. Thesafetyglass provideshielding for thetubeviewing area againstx
ray radiation as well as implosion. Themagneticshieldlimitsthexray radiation around thebell of
thepicturetubeinaddition totherestricting magneticeffects. Whenusing apicturetubetestjig
for service, ensurethatthejigiscapableofhandling 50kV withoutcausing xray radiation.
Beforereturning aservicedreceivertotheowner, theservice technicianmustthoroughlytest
theunittoensurethatiscompletelysafetooperate. Donotuse alineisolation transformerwhen
testing.
Leakagecurrentcoldcheck
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Unplug theA.C. cord and connectajumperbetweenthetwoplug prongs.Measuretheresistance
betweenthejumperedACplug and expose metallicpartssuchas screwheads, antenna
terminals, control shafts, etc. Iftheexposedmetallicparthas areturnpathtothechassis, the
reading shouldbebetween240k and 5.2M . Iftheexposedmetallicpartdoes nothave a
return pathtothechassis, thereading shouldbeinfinite.
Leakagecurrenthotcheck
Plug theACcord directlyintotheACoutlet. Donotuse anisolation transformerduring thecheck.
Connecta1.5k 10 watt resistor inparallel witha0.15 Fcapacitor betweenanexposed
metallicpartand ground. Use earthground, for exampleawaterpipe.
Using aDVMwitha1000 ohms/voltsensitivityor higher, measuretheACpotential across the
resistor.
Repeattheprocedureand measurethevoltagepresentwithall otherexposedmetallicparts.
Verifythatanypotential does notexceed0.75 voltRMS. Aleakagecurrenttester(sucha
Simpson model 229, Sencoremodel PR57 or equivalent) may beusedintheabove procedure, in
whichcase anycurrentmeasuremustnotexceed0.5milliamp. Ifanymeasurementisoutofthe
specifiedlimits, thereisapossibilityofashock hazard and thereceivermustberepairedand
recheckedbeforeitisreturnedtothecustomer.
Hotcheck circuit
Insulation test
Connectaninsulation testerbetweenanexposedmetallicpartand A.C. line. Apply1080VAC/
60Hzfor 1second. Confirm thatthecurrentmeasurementis0.5mA~2.0mA. Repeattestwith
othermetallicexposedparts.
X ray radiation
WARNING
Thepotential source ofxray radiation intheTV setisinthehigh voltagesection and thepicture
tube.
NOTE
Itisimportanttouse anaccurate, calibratedhigh voltagemeter.
Setthebrightness, picture, sharpness and color controlstominimum.
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Measurethehigh voltage. Thehigh voltageshouldbe29.25 ±1.25kV. Iftheupperlimitisoutof
tolerance, immediateservice and correction isrequiredtoinsuresafeoperation and toprevent
thepossibilityofprematurecomponentfailure.
Horizontal oscillator disablecircuittest
Thistestmustbeperformedas afinal check beforethereceiverisreturnedtothecustomer. See
horizontal oscillator disablecircuitprocedurecheck inthismanual.
2. Service notes
NOTE
These componentsareaffixedwithglue. Becareful nottobreak or damageanyfoil underthe
componentor atthepinsoftheICswhenremoving. Usuallyapplying heattothecomponentfor a
shorttimewhiletwisting withtweezerswill break thecomponentloose.
Leadless chipcomponent(surface mount)
Chipcomponentsmustbereplacedwithidentical chipsduetocritical foil track spacing. There
areno holes intheboard tomountstandard transistorsor diodes. Somechipscapacitor or
resistor board solderpadsmay have holes through theboard,howevertheholediameterlimits
standard resistor replacementto1/8watt. Standard capacitor may alsobelimitedfor thesame
reason. Itisrecommendedthatidentical componentsbeused.
Chipresistor have athree digitnumerical resistance code, 1stand 2nd significantdigitsand a
multiplier. Example:162 =1600 or 1.6k resistor, 0=0 (jumper).
Chipcapacitorsgenerallydo nothave thevalueindicatedon thecapacitor. Thecolor ofthe
componentindicates thegeneral rangeofthecapacitance.
Chiptransistorsareidentifiedbyatwolettercode. Thefirstletterindicates thetypeand the
second letter, thegradeoftransistor.
Chipdiodes have atwoletteridentification codeas perthecodechartand areadual diodepack
witheithercommon anodeor common cathode. Check thepartslistfor correctdiodenumber.
Componentremoval
1. Use solderwick toremovesolderfromcomponentend capsor
terminal.
2. Withoutpulling up, carefullytwist thecomponentwithtweezersto
break theadhesive.
3. Donotreuse removedleadless orchipcomponents since theyare
subject tostress fractureduring removal.
Chipcomponentinstallation
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1. Putasmall amountofsolderon theboardsoldering pads.
2. Holdthechipcomponentagainst thesoldering padswithtweezers
orwithaminiaturealligatorclipand applyheat tothepadarea
witha30 watt iron until solderflows. Donotapplyheat formore
than3seconds.
Howtoreplace flatic(requiredtools)
1. Removethesolderfromall ofthepinsofaFlat ICbyusing a
desolderbraid
2. Puttheiron wireunderthepinsoftheFlat ICand pull itinthe
direction indicatedwhileheating thepinsusing asoldering iron. A
small awl canbeusedinsteadoftheiron wire.
3. Removethesolderfromall thepadsoftheFlat ICbyusing ade
solderbraid
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4. Position thenew Flat ICinplace (applythepinsoftheFlat ICto
thesoldering padswherethepinsneedtobesoldered). Properly
determinethepositionsofthesoldering padsand pinsby
correctlyaligning thepolaritysymbol
5. Solderall pinstothesoldering padsusing afinetippedsoldering
iron
6. Check withamagnifierforsolderbridgebetweenthepinsorfor
dryjointbetweenpinsand soldering pads. To removeasolder
bridge, use adesolderbraidas showninthefigurebelow
IMPORTANT
Toprotectagainstpossibledamagetothesolidstatedevices duetoarching or staticdischarge,
make certainthatall ground wires and CRTDAGwirearesecurelyconnected.
CAUTION
Thepowersupplycircuitisaboveearthground and thechassis
cannotbepolarized. Use anisolation transformerwhenservicing
thereceivertoavoiddamagetothetest equipmentortothe
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chassis. Connect thetest equipmenttotheproperground(hot) or
(cold)whenservicing, orincorrect voltages will bemeasured.
2.1. X-RayProtection CircuitCheck&Adjustments
Thistestmustbeperformedas final check beforethereceiverisreturnedtothecustomer. If
voltages areoutoftolerance, immediateservice and correction isrequiredtoinsuresafe
operation and topreventthepossibilityofprematurecomponentfailure.
Equipment:
1. Isolation transformer.
2. High voltagemeter.
3. D.C. Ammeter
4. Shortjumper.
5. HHSjig(See figurebelow).
DiodeConnection Jumper.
Preparation:
1. Make surethereceiveristurnedoff.
2. Connect thereceivertoanisolation transformer.
3. Connect theammeterserial fromtheflyback anodeleadtothe
picturetubeanodesocket.
4. Prepareshortjumperand HHSjig.
Procedure:
1. Connect theshortjumperbetweenTPD16 &TPD17.
2. Connect thejumperdiodebetweenTPD14 and TPD15 (anode
connectedtoTPD15 and cathodetoTPD14).
3. Apply75VACtoACinputofisolation transformer.
4. Turnthereceiveron.
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5. Applyamonoscopepattern.
6. Set customerpictureand brightness controlstotheminimum.
7. Set currentwithin50 Ato100 Abychanging thepictureand
brightcontrols.
8. Slowlyincrease ACvoltageat theinputoftheisolation
transformerand confirm HHSvoltagemeasure33kV.
9. Turnpoweroff and removejigs.
3. EEPROMreplacement
IfanewEEPROMintegratedcircuitisreplacedfor servicing, followthenextprocedureonce that
thememoryisproperlyassembled:
1. Entertoservice mode.
2. TurntheTVset ON.
3. Once insideservice modethefirst imagethat appearson-screen
istheID1registerwiththerespectiveaddress value(FF)like the
imagebelow.
Note:
All 3registers(ID1,ID2,ID3) shouldappearwithFF values ifanew
EEPROMisassembled.
4. With“VOL”keysadjust thecorrect valueaccording withthe
service adjustmenttable(see “Service Mode”section on page15).
5. Changetothenext IDswitchregisterwith“CH”keysand repeat
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thesameprocedureas step4.
6. Whenreplacing anew EEPROMbesuretoset thecorrect ID
switchvalues foreachmodel.
7. Once that all 3registersareset withthecorrect address value,
perform all oftheremaining adjustments and servicing.
IMPORTANT:
Correct IDswitchconfiguration shouldbeinputwhenreplacing
EEPROMforeachtelevision model, otherwise ifwrong values are
configured, thetelevision softwarewill notfunction accordinglyand
properly.
4. About lead free solder(PbF)
NOTE
Leadislistedas (Pb)intheperiodictableofelements. / Intheinformation below, Pbwill referto
leadsolder, and PbF will refertoLeadFree Solder. / Theleadfree solderusedinour
manufacturing process and discussedbelowis(Sn+Ag+Cu). / ThatisTin(Sn), Silver(Ag)and
Copper(Cu)although othertypes areavailable.
Thismodel uses PbFree solderinit’smanufactureduetoenvironmental conservation issues. For
/ service and repairwork, we’dsuggesttheuse ofPbfree solderas well, although Pbsoldermay
be/ used. / PCBsmanufacturedusing leadfree solderwill have the“PbF”or aleafsymbol
stampedon the/ back ofPCB.
CAUTION
-Pbfree solderhas ahighermelting pointthanstandardsolder.
Typicallythemelting pointis50 ~70 °F(30 ~40 °C)higher. Please
use ahigh temperaturesoldering iron and set itto700 ±20 °F(370
±10 °C).
-Pbfree solderwill tend tosplashwhenheatedtoo high (about1100
°For600 °C). / Ifyou must use Pbsolder, please completely
removeall ofthePbfree solderon thepinsorsolderarea before
applying Pbsolder. Ifthisisnotpractical, besuretoheat thePb
free solderuntil itmelts, beforeapplying Pbsolder.
-Afterapplying PbF soldertodoublelayeredboards, please check
thecomponentsideforexcess solderwhichmayflow ontothe
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opposite side.
SuggestedPbfree solder
Thereareseveral kindsofPbfree solderavailablefor purchase. Thisproductuses Sn+Ag+Cu
(tin, silver, copper)solder. However, Sn+Cu(tin, copper), Sn+Zn+Bi (tin, zinc, bismuth)soldercan
alsobeused.
5. Receiverfeaturetable
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FEATURE/MODEL CT-27C8G CT-27L8G/UG/SG CT-27G8G
/
CHASSIS BP404 AP404
MICRO 128K
MENU LANGUAGE ENG/SPAN/FR
CLOSEDCAPTION X
V-CHIP (USA/CANADA) X
CHANNELCOUNT 181
REMOTE CONTROL EUR7613Z10 EUR7713010
CRTSUPPLIER MDDA
CHASSIS NA10
COMBFILTER DIGITAL
V/ANORM(X=BOTH) V
MTS/SAP/DBX X
BUILT-INAUDIOPOWER 1.5Wx2 (10%)
No. OFSPEAKERS 2
AISOUND X
A/V IN(REAR/FRONT) 2(2/1)
COMPONENTINPUT(Y, Pb, Pr) 1 ---
S-VIDEOINPUT(REAR/FRONT) 1/0
DIMENSIONS(WxDxH) 754.3x534.3x601.6mm29.69x21.03x23.68in665.2x544.5x594.8mm26.18x21.43x23.41in
665.2x544.5x594.8mm26.18x21.43x23.41in
WEIGHT(Kg/Lbs) 35.4/78.04 34.5/76.05 34.5/
76.05
VIDEOINPUTJACK 1Vp-p75 , phono jack
AUDIOINPUTJACK 500mV RMS 47k
HEADPHONE JACK X
Note:
Specificationsaresubjecttochangewithoutnotice or obligation. Dimensionsand weightsare
approximate.
6. Boarddescription table
CT-27G8G/ CT-27G8UG
BOARD PARTNUMBER DESCRIPTION
ATNP2AH047GA MAINBOARD
CTNP2AA122GA CRTBOARD
CT-27L8G/ CT-27L8UG/ CT-27L8SG/ CT-27C8G
BOARD PARTNUMBER DESCRIPTION
ATNP2AH047GB MAINBOARD
CTNP2AA122GA CRTBOARD
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NOTE
Whenordering areplacementboard assembly, append an“S”totheboard number
EXAMPLE
ToordertheABoard, for CT-27G8Gthereplacementboard isTNP2AH047GAS.
7. TVLocation of controls
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8. Location of controls(remote)
8.1. EUR7713010
Note:
For additional information aboutthisremoteplease refertotheowner’smanual section remote
operation, listedon thepartslistsection.
8.2. EUR7613Z10
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Note:
For additional information aboutthisremoteplease refertotheowner’smanual section remote
operation, listedon thepartslistsection.
9. Dissasemblyforservice
Back cover
Remove all thescrewsmarkedwithanarrow( )from theback ofthereceiver
NOTE
Screwconfiguration, type, and numberofscrewsvarydepending on themodel ofthereceiver
servicedand theapplication;variousmodelsarecoveredinthismanual. Use samehardware
whenreassembling thereceiver.
-3screwsat thetop edgeofthereceiver.
-1screw bytheA/Vjacks.
-1screw at eachlowercornerofthereceiver.
-1screw bytheFlyback.
-1screw bytheACcord(onlyinCT-27C8G models).
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A-Board -Mainchassis
1. Slidethechassiscompletelyoutoftheguiderails.
2. Stand thereceiveron its edge. Theundersideoftheboardis
completelyaccessibleforcomponentreplacement.
Note:
Sometie-wrapsthatsecurethewiredressingsmay needtobeunfastenedfor chassisremoval.
C-Board -CRToutput
Theboard plugsontothesocketon theCRTneck. Torelease theFocuswire, use adull objectto
release thetabon thesocket(nearthewireopening)and carefullypull on thewire. Toconnect
thefocuswire, press on thetabtolock ittheninsertthewireintheopening and press on ituntil it
isfullyinsertedand lockedinplace.
Focuscablerelease
Speakers
Eachspeakerissecuredtothecabinetwith4screws.
NOTE
Whenreassembling speakersbesuretoconnectthespeakerwires tothecorrectspeakerlead(+)
(-)
9.1. DisassemblyforCRTreplacement
1. DischargetheCRTas instructedinthe“safetyprecautions”.
2. Disconnect theyoke (DY)plug, degaussing coil (DEG)plug from
themainboard.
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3. Unplug theCRT2nd anodebutton fromthemainboard.
4. RemovetheC-BoardfromtheCRTbase and unplug theblack
wires (CRTdagground)C10 &C11.
5. Disconnect thespeakersplug fromtheA-Board.
6. Lift themainchassis(A-Board)and all mountedboardscompletely
outwiththeCRTboardattached.
7. Perform complete removal ofchassis, as instructedin
“disassemblyforservice”section.
CRTreplacement
1. Perform “disassemblyforCRTreplacement”procedure.
2. Insurethat theCRTH.V. Anodebutton isdischargedbefore
handling theCRT. Readthe“safetyprecautions”section on
handling thepicturetube.
3. Removethecomponents fromtheCRTneck and place thecabinet
face downon asoft pad.
4. Note theoriginal orderfortheCRTmounting hardwareas theyare
removefromtheCRTmounting brackets at eachcornerofthe
CRT.
5. RemovetheCRTwiththedegaussing coil and thedagground
braidattached.
6. Note theoriginal locationsand mounting ofthedegaussing coil
and thedagground assemblytoinsureproperreinstallation on
thereplacementCRT.
To removeand remountthedegaussing coil:
-Unhookthecoil spring fromthebottomcornersoftheCRT
ears.
-Release thebraidloop fromtheuppercornersoftheCRTears.
7. Mountthedagground braidon thereplacementCRT. Position the
degaussing coil withnew ties.
Dress coil as was on theoriginal CRT.
8. Replace thecomponents on CRTneck and reinstall intocabinet.
Verifythat all ground wires and circuitboardplugsget connected.
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IMPORTANTNOTICE
Whenordering theCRT, please orderCRTand CRTkitalso.
Please see parts list section forpartnumbers.
9.2. Back CoverRemoval Back Cover(CT-27C8G).
Back Cover(CT-27L8G/UG/SG, CT-27G8G/UG)
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10. Chassisservice adjustment procedures
All service adjustmentsarefactorypresetand shouldnotrequireadjustmentunless controlsand/
or associatedcomponentsarereplaced.
Note:
Connect the(-) leadofthevoltmetertotheappropriate ground. Use
IC801’sheat sinkwhentheHOTground symbol isused. Otherwise,
use COLDground (Tunershield, IC451’sheat sinkorFA2).
Componentand VoltageTestPoints
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Note:
Components and test points withindotedareas arelocatedon trace
side.
B+voltagecheck
1. Set theBRIGHTand PICTUREtominimumbyusing thePICTURE
menu.
2. Connect theDVMbetweenC825 (+side) orTPD14 and cold
ground.
3. Confirm that B+ voltageis131.0V±2.0V. Thisvoltagesupplies B+
tothehorizontal outputand flyback circuits.
Source voltagechart
120V AClineinput. SettheBRIGHTand thePICTURE tominimum byusing thePICTURE menu.
Use coldor hotground for the(-) leadoftheDVMas needed.
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A-BOARD TEST
POINT VOLTAGE
+B2 TPD14 131.0±2.0V
SOUND C823 (+) 18.1±1.0V
STB12V C827 (+) 12.8±1.0V
220V TPA14 217 ±10 V
VERTICAL TPD8 27.4±1.5V
9V IC551 pin3 9.0±0.5V
5V IC552 pin3 5.0±0.5V
3.3V IC005 pin2 3.3±0.3V
EHT CRTanode 29.25 ±1.25kV
HEATER JK351 H-
HGND 6.0±0.24V
High voltagecheck
1. Select anactiveTVchannel and confirm that horizontal isinsync.
2. Adjust BRIGHTNESS and CONTRASTusing PICTUREicon menu
sovideojust disappears.
3. Using ahigh voltagemeterconfirm that thehigh voltageis29.25 ±
1.25kV.
11. Service mode (electronicadjustments)
Thisreceiverhas electronictechnologyusing theICbusconcept. Itperformsas acontrol
function and itreplaces manymechanical controls. Insteadofadjusting mechanical controls
individually, manyofthecontrol functionsarenowperformedbyusing “on screendisplay
menu”. (Theservice adjustmentmode).
NOTE
Itissuggestedthatthetechnicianreadsall theway through and understand thefollowing
procedurefor entering/exiting theservice adjustmentmode;thenproceedwiththeinstructions
working withthereceiver. Whenbecoming familiarwiththeprocedure, theflowchartfor service
modemay beusedas aquick guide.
Quick entrytoservice mode
Whenminor adjustmentsneedtobedonetotheelectroniccontrols, themethod ofentering the
service modewithoutremoval ofthecabinetback isas followsusing theremotecontrol:
1. Select SET-UPicon and select CABLEmode.
2. Select TIMERicon and set SLEEP timefor30 Min.
3. Press “ACTION”twice toexitmenus.
4. Tunetothechannel 124.
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