Field Service Procedure – Replacement Pol Motor Kit, 4012
Page1of10
Document No
136830 Rev A
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1. BriefSummary:
Troubleshootingdocumentfordiagnosingafaultwithandreplacingthepolmotoronthe4012antenna.
2. Checklist:
VerifyRangeofMotion
VerifyPotRange
MeasureMotorVoltage
VerifyHarness
3. TheoryofOperation:
ToensuretheLNBiscorrectlyalignedtothelinearpolarizedreceivesignaltheantennasfeedassemblycanbedriven
througha270degreerangeofmotionbya24VDCmotor.BasedonthevesselsGPSpositionandthelookangletothe
desiredsatellitethesystemwillcalculatethenumericalvalueforthepositionofthepolassembly.TheICUwillthensend
thevoltagetodrivethepolmotoruntilthepolpotoutputsthecorrectvalue,atwhichpointthefeedwillbealignedto
theincomingsatellitesignal(providedthepothasbeencalibratedcorrectly).ThenasthevesselsailsandtheGPS
positionchangesthelookangletothesatellitewillalsochangeandadjustmentswillbemadetomaintaingoodcrosspol
isolation(alignmenttothesatelliteslinearsignal).
Oneindicationthatthereisafaultwiththefeedalignmentofthesystemisthatthetargetlightwillbepermanently
illuminatedontheMXPandtheantennawon’ttargetcorrectly.Ifthisisthecaseitwillsit8degreesaboveor8degrees
belowoftheelevationlookangle.Thisisbecausepartoftheantennastargetingprocedureistotargetthesystemabove
orbelowthesatellite,tocalculatetheautothresholdsettingbasedonthenoisefloorlevel,thenitwillalignthefeedfor
thecorrectreceptionpositionbasedonthevesselsGPSpositionbeforetargetingthesatellite.
Ifthesystemisunabletodrivethepolmotororthepolpothasfailed,thecorrectfeedbacksignalisnotobtained,the
systemcan’tcompletethetargetingprocessandtheantennawillstayinthisposition.Settingthepoltypemanualmode
willallowtheantennatotargetcorrectly,misalignmentofthefeedwillcausebadcrosspolisolation.
4. VerifytheFeedAssembliesRangeofMotion:
Toverifyifthe4012antennaspolarityfunctioniscalibratedcorrectlyrefertosection3ofthisdocument.
Onceverifiedthatthepotiscalibratedthenextstepwillbetoverifythatthesystemhasthefullrangeofmotion(135
degreesofphysicalrotation),verifyingthatthepolpotisoutputtingthecorrectresistancethroughitsrangeandalso
thatthepolmotorisdrivingtheassemblycorrectly.
1. Toverifytherangeofmotiononthefeedassemblyenterintothe“Reflector”screenundertheconfiguration
optionsandsetthepolangdrivemodetomanualandclickthesavebutton.
