Field Service Procedure – Replacement Pol Motor Kit, 3011
Page1of7
Document No
136825 Rev A
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1. BriefSummary:
Troubleshootingdocumentfordiagnosingafaultwithandreplacingthepolmotoronthe3011antenna.
2. Checklist:
VerifyRangeofMotion
VerifyPotRange
MeasureMotorVoltage
VerifyHarness
3. TheoryofOperation:
Toensurethereceiveandtransmitpathsofthesystemarecorrectlyalignedtothelinearsatellitesignaltheantennas
feedassemblycanbedriventhrougha180degreerangeofmotionbythe24VDCpolmotor.BasedonthevesselsGPS
positionandthelookangletothedesiredsatellitetheDACwillcalculatethenumericalvalueforthepositionofthepol
assembly.ThePCUwillthenissuevoltagetodrivethepolmotoruntilthepolpotoutputsthecorrectvalue,atwhich
pointthefeedwillbealignedtotheincomingsatellitesignal(providedithasbeencalibratedandisfunctioning
correctly).ThenasthevesselsailsandtheGPSpositionchangesthelookangletothesatellitewillalsochangeand
adjustmentswillbemadetomaintaingoodcrosspolisolation(alignmenttothesatelliteslinearsignal).
Oneindicationthatthereisafaultwiththefeedalignmentofthesystemisthatthetargetlightwillbepermanently
illuminatedontheDACandtheantennawon’ttargetcorrectly.Ifthisisthecaseitwillsit8degreesaboveor8degrees
belowoftheelevationlookangleofthesatellite.Thisisbecausepartoftheantennastargetingprocedureistotargetthe
systemaboveorbelowthesatellite,tocalculatetheautothresholdsettingbasedonthenoisefloorlevel,thenitwill
alignthefeedforthecorrectreceptionpositionbasedonthevesselsGPSlocationandthelookuptableintheDAC,
beforetargetingthesatellite.
Ifthesystemisunabletodrivethepolmotororthepolpothasfailedandthecorrectfeedbackfromthepotisnot
obtained,thesystemcan’tcompletethetargetingprocessandtheantennawillstayinthisposition.Settingthepoltype
to“0009”willputthesystemintomanualpolmodewillallowtheantennatotargetthesatellite,howevermisalignment
ofthefeedwillcausebadcrosspolisolation.
4. VerifyRangeofMotion:
FirstverifythesettingsintheDACarecorrect,thepolscaleshouldbesetto“0090”togivethefeed180degreesof
motion.Thedefaultpoloffsetsettingfora3011antennais“0040”.Youmayfindthesehavebeenmodifiedslightlyto
“trim”thepolangle.
InthesetupmenuoftheDACsetthepoltypeto“0009”.Thischangestheoperationmodeofthepolassemblyfrom
automatic(poltype“0072”)tomanualtherebyremovingtheautomaticcalculationbasedonthevesselsGPSposition
andallowsthefeedassemblytobemanuallydrivenfordiagnosticpurposes.Nowenterthepolwindowanddrivethepol
assemblydownintoitslowerendstop,observethepositionofthefeed.Nowdrivethepolassemblyup,thefeedshould
move180degreesundernormaloperation.
