Sea Tel 2406 User manual

Field Service Procedure – Replacement Level Cage Kit, 2406
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137303 Rev A
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Tel, Inc. This document may not be reproduced or distributed in any form without prior written
consent of Sea Tel, Inc. 
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1. BriefSummary:
Troubleshootingdocumentfordiagnosingafaultwithandreplacingthelevelcageassemblyonthe2406antenna.
2. Checklist:

VerifyRemoteTilt
VerifyInitialization
VerifySensorOutputsusingDacRemP
AzimuthandRelativeTargeting
DriftandSensorMonitoring
3. TheoryofOperation:
Thelevelcagecontains4sensors.Theseareafluidfilledtiltsensorwhichisusedasthesystemshorizonreference(level
position)andlongtermstabilizationreferenceand3solidstateratesensors,oneforeachaxiswhichactsastheantennas
shorttermstabilizationreference.Afaultysensorinsidethelevelcagewillcausetheantennatolosestabilityand
mispointfromthesatelliteunderdynamicconditionsalthoughthesystemmayappeartobeoperationalintheport
whenthereisnomotiontocounteract.Thisdocumentwillrunthroughtestingthesensorsinsidethelevelcage,
replacingthelevelcageassemblyandcalibratingthesystemsremotetiltsetting.
4. VerifyRemoteTilt:
Ifthepedestalishavingstabilityproblemsfirstlychecktheremotetiltsettingbylookingatthelevelbubbleontopofthe
levelcage.Ifthebubbleisn’tasclosetocentralaspossibletheremotetiltsettingisn’tcorrectlycalibrated,meaningthe
ratesensorswon’tbecorrectlyalignedwiththeiraxis.Thiswillcausetheratesensorstooutputincorrectfeedbackinto
thePCUscontrolloop,potentiallycausingastabilizationissue.Calibratetheremotetiltsettingaspertheinstructionsat
theendofthisdocumentandcontinuetotestthelevelcageusingthefollowprocedures.
5. VerifyInitialization:
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Powercyclethepedestal:
1. Levelcagedrivestoitsendstop,thenbacksoffexactly45degrees
2. Elevationaxisdrivesto45degreesbasedonthelevelcageshorizonreference
3. Crosslevelaxisdrivestolevelbasedonthelevelcageshorizonreference
4. Unlimitedazimuthaxisdrivesclockwiseuntilthehomeflagandsensormakecontact
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Ifanyofthesestepsfail,ortheACUreportsmodel“xx03”,theantennasN0parameterneedscalibratingandverifiedit
savescorrectly.Adriveissueorpedestalerrorrequiresfurthertroubleshooting.
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Field Service Procedure – Replacement Level Cage Kit, 2406
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6. VerifyStabilization:
Thepurposeofthisprocedureistophysicallymovethesystemsaxisunderstaticconditions,introducingerrorintothe
PCU’scontrolloopandthenverifythesystemisabletoreturntoitslevelposition(stabilizeitself)efficiently.Thesetests
canbeperformedbymonitoringthesensoroutputsonDacRemPoralsobyphysicallymovingtheantennaandobserving
howitresponds.

1. TurntrackingoffandOpentheDISP_VscreenofDacRemP,itwillnowplotthelevelpositionofthetiltsensor.
Alternativelyobservethepedestal.Normaltraceis+/‐4divisionsfromredline.
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2. VerifyCrossLevelresponse:
Pushthecrosslevelbeamdowntotheleft(CCW)andholditinposition.VerifythattheCLtraceonDacRemP
movesdownanequalamounttothemovementexertedontheaxis.ReleasetheAxisandverifytheDacRemPtrace
returns(orthesystemsaxisreturns)backtoitsoriginalpositioninstantly,withoutdeviatingortakingtimetosettle.
Nowpushthecrosslevelbeamdowntotherightandholditinposition.VerifythattheCLtraceonDacRemP
movesupanequalamounttothemovementexertedontheaxis.ReleasetheAxisandverifytheDacRemPtrace
returns(orthesystemsaxisreturns)backtoitsoriginalpositioninstantly,withoutdeviatingortakingtimetosettle.

3. VerifyLevel(Elevation)response:
PushtheReflectorupinElevation(CCW)andholditinposition.VerifythattheLVtraceonDacRemPmovesdown
anequalamounttothemovementexertedontheaxis.ReleasetheAxisandverifytheDacRemPtracereturns(or
thesystemsaxisreturns)backtoitsoriginalpositioninstantly,withoutdeviatingortakingtimetosettle.Pushthe
ReflectordowninElevation(CW)andholditinposition.VerifythattheLVtraceonDacRemPmovesupanequal
amounttothemovementexertedontheaxis.ReleasetheAxisandverifytheDacRemPtracereturns(orthe
systemsaxisreturns)backtoitsoriginalpositioninstantly,withoutdeviatingortakingtimetosettle.Shouldthe
systemtaketimetosettle,ornotstabilizetotheoriginalposition(notnecessarilyontheredline)thenthisisan
indicationthattheantennaisn’tmaintainingitshorizonreferencecorrectlyandfurthertroubleshootingwillneedto
beundertaken



IfusingDacRemPthetraceshouldlooksimilartothisimage,notehowaftereachmovementthesystemreturnstoits
levelpositionefficientlywithouttakingtimetosettle.

Field Service Procedure – Replacement Level Cage Kit, 2406
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consent of Sea Tel, Inc. 
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7. RateSensorMonitoring:
RatesensoroutputscanalsobemonitoredusingtheDISP_WscreenofDacRemPtoverifyanydeviationsunderstatic
conditions.Thetracesshouldremainconsistent,anydriftingorspikesareanindicationthesensorsvoltageoutputis
changingandthesensorisdefective(providednoforcesarebeingexertedonthesystem).Normaltraceis+/‐1division
fromredline.

8. AzimuthTargeting:
Shouldtheantennahaveissuestargeting,suchasnotaccuratelyfindingthesatelliteorrepeatedlyfindingthesatellitein
differentazimuthpositions,thenit’simportanttoascertainifthesystemismispointinginazimuthorrelative.Relative
feedbackfromtheazimuthencodercanbeverifiedbyinitializingthesystem,verifyingitcalibratesitselfcorrectlyand
thendrivingthepedestalclockwisein90degreeincrementsovera360degreerotation,notingthatthesystempoints
correctly(bow,starboard,aft,port,bowandstarboard)andthatnoazimuthreferenceerrorisflaggedbythePCU.A
mechanicalproblemsuchasthebeltskippingonthepulley,oranotherphysicalrestriction,couldalsocausethiskindof
error.Skewingtheantennainazimuthbyholdingtherightorleftarrowkeytodrivetheantennaslowlymayalsopresent
anissue.Ifthesystemkeepsfindingthesatelliteatdifferentazimuthpositionsbutatthesamerelative,thentheencoder
isfunctioningcorrectlyandtheazimuthratesensoriscalculatingthemovementincorrectlycausingtheantennato
mispoint.
9. Drift:
Anotherfailurewhichcanoccurisifaratesensorstartsdrifting.Thismeansthesensorsvoltageoutputdeviatesfrom
whatthePCUisexpecting(2.5VDC),whichintroduceserrorintothecontrolloop.It’smorecommontoseethisinthe
azimuthaxisasthecrosslevelandelevationaxishavethetiltsensorastheirlongtermreference(althoughshouldthe
ratesensorsdriftbelargeenoughtooverpowerthetiltsensoryouwouldseethesystemdrivingintooneofthecross
levelorelevationendstops).
Toverifyifthesystemisdriftinginazimuthturnofftrackingandmonitortherelativeposition,understaticconditions
(i.e.whenthevesselsheadingisn’tchanging),itshouldremainstill.Iftherelativevaluebeginstoincrease/decreasefrom
itsnominalpositionthentheazimuthratesensorisdrifting,feedingerrorintothePCU’scontrolloopwhichiscausing
thePCUtobelievethevesselsheadingischangingandinturndrivingtherelativeintheoppositedirectionto
compensate. 

Field Service Procedure – Replacement Level Cage Kit, 2406
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10. Diagnostics:
Anyincorrectreadingsfromtheabovetestswouldrelatetoanerrorintheantennascontrolloopcausingthesystemto
notstabilizecorrectly.Themostlikelycauseofthisisadefectivesensorinthelevelcage.Thenextstepwillbetoreplace
thelevelcageandrepeatthetestwhichtheantennafailedtoverifyifthesystemisnowfunctioningcorrectly.
Shouldtheproblempersistotherpossibilitiesareabadconnectiononthereferenceharnessbetweenthelevelcageand
PCUcorruptingthefeedback,orpossiblythePCUitselfnotcalculatingthefeedbackcorrectly.Howeverasthelevelcage
isthemostlikelycomponenttobecausingthisissuereplacingitisthefirststepinthetroubleshootingprocedure.
Oncetheproblemhasbeenrectifieditsgoodpracticetorefittheoriginallevelcageandseeifthefaultreturns.It’s
possiblethattherewascorrosiononthepinsofthereferenceharnessandbyconnectingthereplacementlevelcagethe
pinshavebeencleaned,allowinggoodmetaltometalcontactandgivingtheimpressionthatreplacingthelevelcage
rectifiedthefault(cleaningthepinsonthePCUendofthereferenceharnessisalsoadvisable).
11. FurtherInformation:
Shouldthesystemfailtotargetthecorrectelevation(physicallypointingatadifferentpositiontothereadingonthe
DAC)orhaveissuesdrivingpastacertainelevationpositionthenthemostlikelycauseisadefectivelevelcagemotor.
Ifthesystemisdisplayingapedestalerror(error8)thenthereisadriveissuewiththeantennaandattentionwillneedto
bepaidtothemotorandmotordriver(insidethePCU)fortherelevantaxis.Adefectivelevelcagewon’tflaganerror8
asthePCUdoesn’tknowifthefeedbackfromthelevelcageiscorruptwhichiswhytheantennawillmispointifthelevel
cageisdefective.
Anotherpotentialissuewhichcouldcausetheantennatolosethesatelliteisifthevesselsgyrocompassisdrifting,
accumulatingerrorwhichisthenfedintothecontrolloop.ThiscanbeverifiedbyrunningaDacRemPlogfileatseato
monitorthepedestalsreadingswhentheAGCdrops,orbyputtingthesystemintosatellitereferencemodetobypass
thegyrofromtheazimuthcontrolloop.
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12. XX06LevelCageInstall:
*Note:HowtheNylocknutisinstalled,tensioningthecentrecollarofthebearing,preventingthelevelcagefrom
movingfromsidetosideonthespindle,notovertightenedsoitcanmovesmoothly.


13. ReplacingtheLevelCageAssembly:
13.1. Tools.

2mmFlatBlade(Terminal)ScrewDriver
#1PhillipsScrewdriver
½”Wrench/Spanner
13.2. Procedure.
Procedureforreplacingthelevelcageassembly,SeaTelkitpartnumber:137301(levelcageassemblypartnumber:
122937‐2)andtensioningthelevelcagebelt.

*Caution:Powerdownthepedestalbeforefollowingthis
procedure.
1.Usinga2mmflatbladescrewdriverloosenthescrews
securingthereferenceharnessD‐Subconnectortolevelcage.
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2.Usinga#1Phillipsscrewdriver,loosenthefourscrews
attachinglevelcagemotortotheELpan(donotfully
remove).
3.Slidethemotortowardsthereflectorandremovethebelt
fromlevelcagemotorsprocket.


4.Usinga½”socketorwrenchremovetheNylocknut
securingthelevelcagetothespindle.


5.Takecarenottoremovethelevelstandoffspacerfromthe
spindle.


6.Installthereplacementlevelcageontothespindle,slipping
thebeltoverthelevelcagepulleyandmakingsureitsend
stopsarealignedcorrectly.Secureitwiththe1/2”Nylocknut,
tightenedsoitslightlypreloadsthebearings.
7.Rotatethelevelcagebyhandandverifyithas90degreesof
motionandthatthecagerotatesfreelywithoutrubbing
againsttheELpan.



8.Placethebeltonthelevelcagesprocketandthenslipit
overthesprocketofthelevelcagemotor.
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9.Tensionthebeltbyslidingthemotorassemblybyhand
awayfromlevelcageandtightenoneofthefourscrews.


10.Increasethebelttensionuntilthebeltcanonlybeeasily
twistedjust¼turnwithyourfingers.
11.Ifthebelttensionistootight/loseadjustuntilcorrectand
thensecurethemotor.


12.PlugthereferenceharnessbackintothelevelcageD‐Sub
connectorandtightentheretainingscrews(noneedto
Loctiteassplitwashersareinstalledontheharness).
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14. CalibratingtheRemoteTiltSetting:
Thisprocedureisrequiredtocalibratethelevelcagesothatallthesensorswillbeaccuratelyalignedtotheiraxis.The
fluidfilledtiltsensorprovidesatwodimensionalhorizonreference.Thesystemisnotabletoautomaticallycalculatethe
exactcentervalue,thereforeitisnecessarytoperformthisproceduretomanuallyenteranyoffsetrequiredtomakesure
thePCUreceivesatruehorizonreference.

1. Turndishscanoff:
EnterintotheSetupMenubypressingandholdingthearrowstogetheruntiltheELTrimorAutoTrim
parameterisdisplayed.
Usethearrowkeytoscrollthroughthemenuuntilthedishscanwindowisdisplayed.
Pressthearrowtoactivatethewindowandthenpressthearrow,followedbythebuttontoturn
dishscanfromontooff.
*Note:Whenyoupressthearrowtoturndishscanoffyouwon’tseethedisplaychangeuntilyoupressthe
button.

(Steps2‐7requiresassistancetoobserveandoperateantennasimultaneously)

2. EnterintotheSetupMenubypressingandholdingthearrowstogetheruntiltheELTrimorAutoTrim
parameterisdisplayed.

3. PushthearrowkeyuntiltheRemoteTiltwindowisdisplayed.

4. PushthearrowkeytoactivatetheRemoteTiltsetting.

5. Usethearrowkeystopositionthebubbleasclosetothecenteraspossible.Eachpressofanarrowkeyonthe
directionalpadwillmovetheRemoteTilt½adegree.Itisadvisedthatyouonlypressthebuttononceandwaitfor
theaxistomovebeforepressingitagain.

Whenstandingbehindtheantennalookingatthebubble,ifthebubbleisovertotheright,youneedtopressthe
(right)arrowtobringthebubbleintothecenter.Ifthebubbleisdowntowardsyou,youneedtopressthe
(down)arrowtobringittowardsthecenter.Ifthebubbleistotheleft,youneedtopressthe(left)arrowandif
thebubbleisuptowardsthetop,youneedpressthe(up)arrowtomoveittowardsthecenter.
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Whencorrectthebubbleshouldbeasclosetothecenterofthefluidaspossible


6. WhenthebubbleisascentralaspossiblepressthebuttontodeactivatetheRemoteTiltsetting.

7. Turndishscanon:
EnterintotheSetupMenubypressingandholdingthearrowsuntileithertheELTrimorAutoTrim
parameterisdisplayed.
Usethearrowkeytoscrollthroughthemenuuntilthedishscanwindowisdisplayed.
Pressthearrowkeytoactivatethewindowandthenpressthearrowkey,followedbythebuttonto
turndishscanfromofftoon.
*Note:Whenyoupressthearrowtoturndishscanonyouwon’tseethedisplaychangeuntilyoupressthe
button.

8. SavetheRemoteTiltsettinginthePCU:
PressthearrowkeyuntiltheRemoteParameterswindowisdisplayed.
Pressthearrowkeytoactivatethewindowfollowedbythebutton(you’llseeaconfirmationonthe
displaysaying“Saved”).

9. AsgoodpracticemakeanoteofyourN4andN5parametersonceyouhavecorrectlysettheremotetilt.TheN4and
N5parametersareanumericreadoftheremotetilt.Todothisgototheremotecommandwindowandkeyin
N4999toreadtheCLsetting,followedbyN5999toreadtheELsetting.