Sharp SD-AT1000W Especificaciones descargar pdf (Pagina 214)

Section-5 Maintenance

October 17, 2013

5‐34

WARNING:Disconnectprimarypower priortoservicing. 888‐2693‐004

STEP 17 Verifythataforwardpowersamplefromtheafterthefinalamplifierbut

beforethefilterisconnectedtothePOST‐FILTERportonthebackofthe

LPU.Thermslevelofthesampleshouldideallybeapproximately‐5dBm.

STEP 18 Verifythattransmitteroutputisconnectedtoaquality50ohmload.

STEP 19 VerifythatthelinearRTACmodeissettoBYP ASS.

STEP 20 Applytheappropriateinternalcustomvideotestpatternspecifiedfor

calculatinglinearcorrection.SetRegModetomanualanddoubleclickon

patterntoverifypatternactivationonspectrumanalyzer.

ForNTSC,useNTSCpattern

b. ForallPAL,useSystemD/Kpattern

STEP 21

Verifythatthepost‐filtersamplelevelisslightlybelowtheblacklineonthe

RTACstatusscreen.

STEP 22 VerifywiththespectrumanalyzerthatthesoundcarrierisswitchedON.

STEP 23 Setsyncleveloffsettoachieve40IRE(NTSC)or300mV(PAL)asnecessary.

STEP 24 SetthelinearRTACmodetoADAPT.

STEP 25 VerifythatthelinearRTACattemptandsuccesscountersincrementto1and

STEP 26 Afteroneortwoadaptations,switchtheRTAClinearmodetoHOLD.

STEP 27 WiththelinearRTACmodesettoHOLD,thelinearequalizationhasbeen

calculatedandappliedtothesignal.Rechecksynclevelwithblackpicture

(nosetup).Adjustifnecessaryfor300mVPALor40IRENTSClevels.

VerifyingLinearEqualizer:

STEP 28

Measuretheamplitudeandgroupdelayresponseacrossthechannel.

STEP 29 WiththelinearRTACinHOLDandthenonlinearRTACinHOLDorSTORED,all

correctionhasbeencalculatedandappliedtothesignal.

STEP 30 PerformtheprocedureinSection5.7.2onpage5‐35tostorethecurrent

correction.Pla

ceLinearandnon‐linearRTACmodestoSTORED.

STEP 31 Proce dur ecomplete.

5.7.1.1 TroubleshootingPrecorrection

IftheRTACmodeissettoADAPT,buttheAttemptscounterdoesnotincrementwithinthirtyseconds,thereisa

problemwiththefeedback.

Checkthesignallev

elsatthePREandPOST‐FILTERinputsonthebackoftheLPU.Theyshouldbebetween‐10dBm

and+5dBm(optimumis0dBmattheinputsonthebackoftheLPU).

ChecktheRT

AClevelsontheSTATUS>RTACGUILPUscreen.Thebarmetersshouldbegreenandthelevelshould

bejustbelowtheblack100%line.

Checktha

ttheexciterHomeScreenshowsONintheupperleftcorneroftheGUIscreen.IftheexciterisOFFor

MUTE,thecorrectionscannotbecalculated.

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