Schonstedt GA-92 XTd User manual

InstructionManual



Model

GA‐92

XTd

™

Magnetic

Locator







Manufactured

By

Schonstedt

Instrument

Company
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100

Edmond

Road,

Kearneysville,

WV

25430

(304)

725‐1050,

Fax

(304)

725‐1095


Web:

www.schonstedt.com

E‐mail:

[e-mail]


Made in

USA





Preface

TheGA‐92XTd™MagneticLocatorisaproductofoversixtyyears’experienceinproducingtheworld’s
finestflux‐gatemagnetometersandmagneticdetectorsforaerospace,militaryandcivilian
applications.TheGA‐92XTd™incorporatestheknowledgeobtainedfrommanufacturingunderthe
mostrigidqualitycontrolstandards.TheheartoftheGA‐92XTd™isitspatentedSchonstedtHeliFlux™
magneticfieldsensors.Thesesensors,acknowledgedtobetheworld’sfinest,makepossiblethe
unequalledperformanceofthelocator.

February2017


2

TableofContents

SECTIONI:INTRODUCTION...................................................................................................................3
SECTIONII:OPERATINGCONTROLS
ON/Volume..............................................................................................................................5
OFF............................................................................................................................................5
GAIN..........................................................................................................................................5
SECTIONIII:VISUALANDAUDIBLEINDICATORS
GainLevel..................................................................................................................................6
BatteryLevel.............................................................................................................................6
SignalStrengthandPolarity......................................................................................................6
SECTIONIV:CONNECTORSANDACCESSORIES
HeadphoneJack.........................................................................................................................7
HeadphoneJackPlug.................................................................................................................7
SECTIONV:BATTERYREPLACEMENT....................................................................................................8
SECTIONVI:OPERATINGRECOMMENDATIONS&APPLICATIONNOTES
SearchProcedure.......................................................................................................................9
BasicSignalPatterns.................................................................................................................10
StronglyMagnetizedMarkers...................................................................................................11
CorrectStakeOrientation.........................................................................................................12
LocatingManholes,SepticTanksandWellCasings..................................................................12
LocatingandTracingBarbedWire............................................................................................13
SearchingAreasalongaChainLinkFence................................................................................14
LocatingValveBoxes.................................................................................................................14
LocatingCast‐IronPipes............................................................................................................15
LocatingSteelDrums................................................................................................................15
LocatingOrdnanceandWeapons.............................................................................................16
OtherNotes..............................................................................................................................17
SECTIONVII:SPECIFICATIONS..............................................................................................................18
SECTIONVIII:TECHNICALSUPPORT.....................................................................................................18
SECTIONIX:WARRANTY/SERVICEINFORMATION...............................................................................19
SECTIONX:PARTSDIAGRAM...............................................................................................................20

ImportantNotice

Schonstedtbelievesthestatementscontainedhereintobeaccurateandreliable;however,their
accuracy,reliability,orcompletenessisnotguaranteed.

Schonstedt'sonlyobligationshallbetorepairorreplaceanyinstrumentproventobedefective
withinsevenyearsofpurchase.Schonstedtshallnotberesponsibleforanyinjurytopersonsor
property,directorconsequential,arisingfromtheuseofanyinstrument..

3

SECTIONI:INTRODUCTION

TheGA‐92XTd™magneticlocatordetectsthemagneticfieldofferromagneticobjects.Itrespondsto
thedifferenceinthemagneticfieldbetweentwosensorsthatarespacedapproximately9.5inches
apart.Thisdifferenceisreferredtoasthe“signalstrength”throughoutthismanualandis
representedintheinstrumentbyanaudiotone,thedisplayofabargraph,andanumericindication.
Inaddition,thepolarityofthesignalstrengthisshownasa+or–signonthedisplay,anddetermines
theside(rightorleft)onwhichthebargraphisdisplayed.Althoughmostobjectscanbelocated
usingtheaudioindicationalone,simultaneoususeoftheaudioandvisualresponseswillprovide
additionalinformationtohelpyoupinpointatargetanddetermineitsorientation.

Figure1illustratesanapplicationoftheGA‐92XTd™locatorinwhichitisusedtodetectaniron
markerusedforpropertylineidentification.Asshown,themagneticfieldoftheironmarkeris
strongeratsensorAthanitisatsensorB.Thiscreatesasignalstrengththatislargerthanzero(which
wouldoccurwhenthefieldstrengthisthesameatbothsensors).

TheaudioresponseoftheGA‐92XTd™isdesignedsothatthefrequencyoftheaudiotoneincreases
asthedetectedsignalstrengthincreases.Asaresult,thefrequencyoftheaudiooutputishigher
thantheidlingfrequency(~30Hz)thatexistswhenthesignalstrengthisapproximatelyzero.The
largersignalstrengthalsocausesthebargraphdisplaytopeakineitherthepositiveorthenegative
direction.


Figure1:DetectingMagneticFieldofanIronMarker


4

TheGA‐92XTd™unitcanbeoperatedeitherintheopenorclosedpositionandanypositionin
between(seeFigure2).

Figure2:OpenandClosedPositions

NOTE:Intheclosedpositionusingnon‐lithiumbatteries,aslightsignalmaybedetectedinthehigh
gainsettingsevenifnoferrousmaterialispresent.Thiscanbeavoidedby1)decreasingthegain,2)
operatingtheunitintheextendedpositionor3)usingalithiumbattery.

TheGA‐92XTd™hasaninternaldetentmechanismtokeeptheunitineitherthefullyextended(open)
orfullyretracted(closed)position.Toextendtheunit,grasptheloopedendofthelocatorandpull
untiltheshaftlocksintoplace.Toreturntheunittotheclosedposition,pushtheloopedendback
intotheshaft.Theunitwilllockintoplace.


5

SECTIONII:OPERATINGCONTROLS

ON/Volume():Toturntheuniton,pushthis
button.Uponturnon,thevolumedefaultsto
HIGH.Pushingthebuttonasecondtimechanges
thevolumetoMEDIUM.Pushingthebuttonathird
timeMUTESthevolume.Additionalpushesofthis
buttoncyclethevolumethroughHIGH‐MEDIUM‐
MUTE.


OFF:Toturntheunitoff,pushthisbutton.


GAIN():Thesensitivityoftheunitcanbe
increased(todetectsmallerobjectsatgreater
depths)ordecreased(todetectlargerobjectsat
smallerdepths)byadjustingthegainupordown
pushingtheUPorDOWNarrowbuttons.









Figure3:GA‐92XTd™FacePlate

6

SECTIONIII:VISUALANDAUDIBLEINDICATORS

GainLevelIndicator:Thegainrangeisindicatedbya4‐
segmentLCDasshowninFigure4:L(Low),M(Medium),H
(High)andXH(ExtraHigh).Uponturnon,thegaindefaultsto
M(Medium).EachpressoftheUPorDOWNarrowbuttons
willcausethegainlevelindicatortochangeaccordingly.

Figure4:GainLevelIndicators

BatteryLevelIndicator:Thebatterylevelisindicatedbya4‐segmentLCDindicator,asshownin
Figure5.Whenallfoursegmentsareblack,thevoltagelevelisbetween100%and75%.Asthe
voltagedecreases,thenumberofblacksegmentsdecreases.
Batterylifevarieswithusageandtheambienttemperature.
Coldtemperaturesreducebatterylife.Lowtemperatures
mayresultinonlytwoorthreesegmentsbeingblack.This
couldbetemporary,andallsegmentswillchangetoblackas
thetemperatureincreases.

Figure5:BatteryVoltageStatus
Indicators


SignalStrengthandPolarityIndicator:Thesignalstrength,definedasthedifference(ordeltaΔ)
betweenthemagneticfielddetectedatthetopandbottomsensors,isshownasanumerical
indicationinmG(milligauss)units,isprecededbythepolarityofthesignal(+or‐),andisfollowedby
theΔsymbol(toemphasizethatitrepresentsa“difference”betweenthetwoendsofthesensor
array).

Inaddition,thesignalstrengthisshownina
semi‐circularbargraph,withmorebars
indicatingastrongersignal.Dependingon
polarity,thebargraphwillswitchtothe+
(right)or–(left)side.Thesignalstrengthis
alsoindicatedbythefrequencyoftheaudio
signal;ahigheraudiofrequencyindicatesa
strongersignal.

Figure6showsthevariousvisualindicationsof
signalstrengthandpolarity.




Figure6:SignalStrengthVisualIndications




7

SECTIONIV:CONNECTORSANDACCESSORIES

HeadphoneJack:Theheadphonejackislocatedonthesideofthe
unitnearthefaceofthelocator.Headphonesareoptionalandmay
bepurchasedfromSchonstedtasanaccessory.Theheadphone
jackismonaural.Standardstereoheadphonesmaybeused,but
theywillproducesoundinonlyoneear.Whentheheadphonesare
pluggedin,thespeakersoundwillbemuted,buttheON/Volume
buttonstillcontrolsthevolumeoftheheadphones.








Figure7:Headphones




HeadphoneJackPlug:AHeadphoneJackPlughasbeenincluded
withthisproduct.Itisrecommendedthattheplugremaininserted
intothejackanytimethatheadphonesarenotinuse.Thisaidsin
makingtheinstrumentmorewater‐resistant.


Figure8:HeadphoneJackPlug


8

SECTIONV:BATTERYREPLACEMENT

TheGA‐92XTd™ispoweredbyone9‐voltlithiumbatterythathasashelflifeoftenyears,andit
providestwicetheoperatinglifeofanalkalinebattery.Thebatteryislocatedinthehandleofthe
instrumentandcanbeaccessedbyturningthescrewcounterclockwise.Toremovethebattery,tilt
theunitsothatthehandleispointingdown,andthebatterywillslideout.Whenreplacingthe
battery,lookattheoutsideofthebatterydoorfortheproperbatteryorientation.Asasafety
measure,theunitwillnotturnonifthebatteryisnotinsertedcorrectly.Youshouldneverhaveto
forcethebatterydoorclosed.Ifthebatterydoesnotseemtobegoinginalltheway,removethe
battery,reverseitsorientationandthenreplaceit.


Figure9:ViewofBatteryDoorandCompartment



9

SECTIONVI:OPERATINGRECOMMENDATIONSANDAPPLICATIONNOTES

SearchProcedure

TurntheinstrumentON.ThegaindefaultstoMedium(M).
GraspthelocatorasillustratedinFigure10.Becausetheupper
sensorislocatednearthehandleoftheinstrument(especiallyif
itisbeingusedinthecollapsedposition),wristwatchesmay
produceunwantedchangesintheaudiosignalandinthemeter
indication.Therefore,watchesshouldberemoved.Keepthe
locatorawayfromyourshoesastheymaycontainmagnetic
material.Toobtainamaximumcoveragearea,sweepthe
locatorfromsidetoside.Whenthelocatorcomeswithinrange
ofanironobject,thesignalstrengthwillpeak,thefrequencyof
theaudiosignalwillpeak,thebargraphwillexpandinthe
positiveornegativedirection,andthedigitalreadoutwillpeak.
ThisisshowninFigure11.



Figure10:SearchingwiththeLocator







Figure11:IllustrationofVisualIndicatorswithin
RangeofanIronObject

NOTE:Thenumberofbarsshowninthebargraph,thenumber
displayedinthedigitalreadout,andthefrequencyoftheaudio
signalwillalldependonthesignalstrength,whichisaffectedby
thetypeofironobjectdetected,itsorientation,andthegain
setting.







10

BasicSignalPatterns

WhentheGA‐92XTd™ispositioneddirectlyoveraverticaltarget,thesignalstrengthwillpeak(audio
signal,digitalreadout,andbargraph)ateitherapositiveornegativepolarity.

Theaudiosignal,digitalreadout,andbargraphindicationsalsopeakovereachendofahorizontal
target.Oneendispositive,theotherisnegative.Thiswillhelpyoutodistinguishbetweentwo
verticalpipesoronehorizontalpipe.Usuallytwoverticalpipesburiedincloseproximitywillproduce
bargraphindicationswiththesamepolarity.


Figure12:SignalsfromVerticalandHorizontalTargets

Afteryouhavedetectedthepresenceofatarget,holdthelocatorverticallyandslowlymoveitback
andforthinan"X"patternwhilelisteningtotheaudioresponseandobservingthebargraph
indicator.Foragivengainsetting,thenumberofbarswillbegreatestwhenthelocatorisdirectly
overaverticaltargetortheendsofahorizontaltarget.The"X"pattern,asshowninFigure13,is
idealforpinpointingsmallobjects.A1‐1/4inchPKnailburiedupto8inchescanbelocatedvery
preciselyusingthistechnique.

Figure13:"X"PatternprovidesPrecisionLocating

Ifyouarelookingforacornermarkeranddetecttwoorthreesignalsinthesamegeneralvicinity,
raisethelocatorseveralinchesabovethegroundordecreasethegainsetting.Anysignalthat

11

disappearswhenthelocatorisheldhigherorwhenthegainisdecreasedislikelycomingfroma
smallertarget.Thesignalfromarustyboltorothersmallitem(seeFigure14)ismuchweakerthan
thesignalfromalargertarget,suchasan18‐inchlengthof3/4inchrebarwhichcanbelocatedat
depthsupto7feet.

Figure14:DecreasinggainEliminatesUnwantedSignals

StronglyMagnetizedMarkers

Astronglymagnetizedmarkerthatisatornearthesurfacewillprovideaweakerindicationonboth
sidesofthemarker,andthatcouldbemistakenforthemarker.

TheheavylineinFigure15representstheincreaseanddecreaseintheaudioandbargraph
indicationsasyoumovethelocatoroveramarker.BetweenpointsAandB,thesignalsincrease
slightlyandthendecrease.JustbeyondB,thesignalsincreaserapidly,peakdirectlyoverthemarker
andthendecreaseatpointC.FromCtoD,thesignalsincreaseanddecreaseagain.Therefore,ifyou
donotmovethelocatorcompletelyacrossthemarker,youmightassumethattheweakerindication
oneithersideofthemarkerisitslocation.Thetwoweakerindicationsoccurbecausethelocatoris
extremelysensitivetothemagneticfieldcomponentsthatareparalleltoitslongaxis.AtpointsBand
C,thefieldisperpendiculartothelocator;therefore,nosignificantaudioorbargraphindicationsare
producedatthesepoints.
Figure15:SignalPatternfromaStronglyMagnetizedMarker

12

CorrectStakeOrientation

Whenplacingstakes,correctorientationisimportant.

Forcheckingpurposes,theorientationofthepin
relativetothelocatorisshowninFigure16.Checkthe
pinwithoneorientation.Thenrotatethepin180°.
Theorientationthatgivesthelargestreadingisthe
onethatshouldbeused.Thisreadingshouldbe
positiveintheNorthernHemisphereandnegativein
theSouthernHemisphere.

Anironpinhastwotypesofmagnetization.Oneisthe
magnetizationinducedbytheEarth'smagneticfield.
Theinducedmagnetizationisalwaysdownwardinthe
NorthernMagneticHemisphereandproducesa
positiveoutputnomatterwhichendofthestakeis
drivenintotheground.Theothertypeoffieldisthe
permanentmagnetizationthatisfixedtothepin.For
maximumdetection,thestakeshouldbedriveninto
thegroundsuchthatthepermanentmagnetizationis
inthesamedirectionastheinducedmagnetization.



LocatingManholes,SepticTanksandWellCasings

Themagneticfieldisstrongestattheedgeofashallowmanholecover.
Youcaneasilytracetheedgesofcoversnearthesurface.Locating
depthsformanholecoversrangeupto8feet.



Figure17:LocatingManholeCovers






Thegreatlengthofawellcasingprovidesastrongfieldatthesurface
thatmakesiteasytolocatecasingsburiedupto15feetdeep.


Figure18:LocatingWaterWellCasings
F
i
gure16:CheckingaStake’s
Orientation

13

TheGA‐92XTd™canalsobeusedtopreciselylocatethemetalhandlesorreinforcingbarsonseptic
tankcoversatdepthsofupto4feet.


Figure19:SignalPatternsProvidedbySepticTankCovers


LocatingandTracingBarbedWire

Youcanoftentracebarbedwire(fromoldfencelines)buried
justbeneaththesurface.Evenifthewireisonlyatrailofrust,
itcanstillbedetectednearthesurface.Tipthelocatoralittle
lowerthanusual‐butnotparallelwiththeground.



Figure20:TracingBarbedWire








Examinetreesforbenchmarksandbitsofembeddedbarbed
wire.Holdthelocatorparallelwiththedirectionofthewire.



Figure21:TracingPiecesofBarbedWireEmbeddedinTrees

14

SearchingAreasalongaChainLinkFence

Searchinginthevicinityofachain
linkfencerequiresareduced
sensitivitysettingandsome
controlovertheorientationof
thelocator.Asillustratedin
Figure22,positionthelocator
horizontallywithitslongaxis
perpendiculartothefence.This
insuresthattheuppersensoris
keptawayfromthefence.

Figure22:Searchinginthe
VicinityofaChainLinkFence

Performthesearchbyslowlymovingthelocatorforwardalongthefencewhilealsomovingittothe
rightandtotheleft.Asyoumoveforward,thistechniqueallowsyoutosearchanareaseveralfeet
wide.Listenforan
abruptdropinthesignal
(asshownbythenullin
Figure23)thatwilloccur
whenthelowersensor,
located1‐1/2inches
fromtheendofthe
locator,isdirectlyover
thestake.Anyvariation
inthepositionofthe
locatorwillproducean
abruptriseinthe
frequencyofthesignal.
Figure23:AbruptDropofSignalwhileSearchingalongaChainLinkFence


LocatingValveBoxes

Boththevalveanditscasing,wheniron,providestrongmagnetic
fieldsthatmakethemeasytolocate.Plasticenclosurescontaining
magnets(whicharetypicallyusedwithnon‐ferrousvalveboxes)are
easilylocatedatdepthsof6feetormore.


Figure24:LocatingValveBoxesandCasings



15

LocatingCast‐IronPipes

AsillustratedinFigure25,cast‐ironpipesproducethestrongestmagneticsignalsattheirjoints.


Figure25:SignalPatternsProvidedbyCast‐IronPipes

Afteraninitialsweepsearchidentifiesthegeneraldirectionofthepipe,thesteelpipejointsor
transitionpointscanbemoreaccuratelytracedbythefollowingprocedure:

1. SettheSensitivitycontroltomaximum(XHindication).
2. Holdthelocatorverticallyapproximately1to1‐1/2feetabovethesurface.
3. Walkwithoutturningortiltingthelocator.
4. Markthelocationswherethemaximumsignallevelsoccur.
5.Returntoanareaofmaximumsignalstrengthandholdthelocatorseveralinches
abovethesurface.Thesensitivitywillprobablyhavetobereducedduringthissecond
pass.Four‐inchpipescanbelocatedatdepthsupto9feet.

LocatingSteelDrums

AsshowninFigure26,the
GA‐92XTd'ssignalpattern
willvarydependingonthe
verticalorhorizontal
orientationofthedrumand
howdeepitisburied.

Afifty‐fivegallondrumcan
belocatedatdepthsupto8
feet.



Figure26:SignalPatterns
ProvidedbySteelDrums


16

LocatingOrdnanceandWeapons

Theversatile,lightweight,cost‐effectiveGA‐92XTd™isalsodesignedtoaidEODtechniciansandlaw
enforcementofficersduringareasearchoperations.




Figure27:BasicSignalPatternsfrom
VerticalandHorizontalTargetsHelpto
DetermineTargetOrientation.









Figure28:A175mmProjectilecanbeLocatedupto4feetdeep.







Figure29:An81mmMortarcanbeLocatedupto12inchesdeep.






Figure30:MK81LowDragBombscanbeLocatedupto7feet
deep.







Figure31:ADiscardedHandGuncanbeLocatedupto12inches
deep.



17

OtherNotes

1.Aburblingsoundindicatesthepresenceofanenergizedpowerline.Thiswillnotinfluencethe
meterindicationunlessitisassociatedwithamagneticstructure.

2.Theinstrumentwillnotrespondtonon‐ferrousmetals,suchasgold,silver,copper,brassand
aluminum.








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18
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SECTIONVII:SPECIFICATIONS
(Specificationssubjecttochangewithoutnotice)
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Output:Audio:Signalincreasesordecreasesinfrequencywithsignal
strength(gradientfieldintensity).Audiofrequencyrange:30to
4000Hz.
Visual:Expandingbargraphand+/‐ signsindicatespolarityand
signalstrength.Digitalreadoutshowsgradientfieldintensity
expressedinmilligauss(mG).Range:0to500mG
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BatteryIndicator4‐segmentLCD
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Gain4‐LevelLCD:Low(L),Medium(M),High(H),ExtraHigh(XH)
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Volume 3Levels:Muted,MediumandHigh
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InputPower One9Vbattery(Lithiumrecommended)
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BatteryLife 24Hours(intermittentusage)
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OperatingTemperature ‐13°Fto140°F(‐25°Cto60°C)
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WaterandDustResistance RatedIP54,whenoperatedwithearphonejackplug(provided)
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OverallLength Open:26”(66cm),Closed:15.5”(39cm)
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NominalSensorSpacing 9.5”(24cm)
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Weight 2.4lb.(1.1Kg)
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ConstructionMaterial HighimpactABS
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SECTIONVIII:TECHNICALSUPPORT
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Schonstedtofferstechnicalsupportandsalessupport.Foranyreasonregardingusageand
applicationpleasecontactourtechnicalsupportteamat888‐367‐7014.
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19
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SECTIONIX:WARRANTY/SERVICEINFORMATION
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LimitedWarranty:
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SchonstedtInstrumentCompany(Schonstedt)warrantseachproductofitsmanufacturetobefree
fromdefectsinmaterialandworkmanshipsubjecttothefollowingtermsandconditions.The
warrantyiseffectivefor7years*aftertheshipmentbySchonstedttotheoriginalpurchaser.Please
completethewarrantyregistrationcardandsendbacktoSchonstedtInstrumentCompany.
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Schonstedt’sobligationunderthewarrantyislimitedtoservicingoradjustinganyproductreturned
tothefactoryforthispurposeandtoreplacinganydefectivepartthereof.Suchproductmustbe
returnedbytheoriginalpurchaser,transportationchargesprepaid,withadescriptionofthedefectin
writing.Ifthefaulthasbeencausedbymisuseorabnormalconditionsofoperation,repairswillbe
billed.Specifically,thiswarrantydoesnotcoverproductthathasbeensubjecttoinundationbyfire,
waterorotherliquidintrusion,orunitsthathavebeendamagedorcompromisedduetorepair,
alterationormodificationbyanyoneotherthananauthorizedrepairrepresentative.Priortoarepair
beingperformedbySchonstedt,acostestimatewillbesubmittedandnoworkwillbecompleted
untilauthorizedbythecustomer.Batteriesarespecificallyexcludedunderthewarrantyandshould
beaddressedtothemanufacturerofbatteriesinquestion.
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Schonstedtshallnotbeliableforanyinjurytopersonsorpropertyorforanyotherspecialor
consequentialdamagessustainedorexpensesincurredbyreasonoftheuseofanySchonstedt
product.
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*ForMilitary& EODapplications,thewarrantyis1year.
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ServiceInformation:
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Ifyourlocatorneedsservice,pleasereturnittothefactoryalongwiththefollowinginformation:
Name,Address,Telephone,Faxnumber,WherePurchased,Date,andDescriptionofTrouble(s).An
estimatewillbeprovidedpriortoserviceworkbeingdone.
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ForServiceorRepair
Pleaseshiplocator(initscase)to:
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SchonstedtInstrumentCompany
100EdmondRoad
Kearneysville,WV25430
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20
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SECTIONX:PARTSDIAGRAM
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