Lowrance LRG-1500A User manual

/
INSTALLATION AND OPERATION MANUAL
MODELS LRG-1500A
AND LRG-1500M
TRULINE RECORDER
LOWRANCE ELECTRONICS,
12000 F. SKELLY DR..TULSA. OKLA.
Printed in U.S.A. 988-0088-02 L! INC.
74128
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

NOTICE
Periodically
wash the TransducerFace with soapand watertore-
move any
of/filmthat
may
collect Oilanddirtonthefacewillreduce
sensitivity
ormayeven
preventsounding.
GOTAPROBLEM? LETUS HELP!
Ifyouhavea
problemwith yoursonar unit,please give usachanceto
helpbefore sending it in for repair.
Assistance canoften beextended bytelephone or letter.Write orcall
oneofourAuthorized ServiceCentersortheLowrance Electronics, Inc.,
Customer Service Departmentin
Tulsa,OK.(Toll-free1-800-331-3889).
Please detailthe problemyouareexperiencing. OurService
Depart-
ment
may
beabletosave
you
theinconvenienceofreturningyour unit.
Ifitisdeterminedthatyour unitmustbereturned,fullshipping
instruc-
tionswill be provided.
SCHEMATIC DIAGRAM ANDPARTS LIST
Should youdesire aSchematic Diagram and Parts listforyourLow-
ranceTRUELINE RECORDER,send$1 .00toPARTS
LIST,Lowrance
Electronics, Inc.,12000 EastSkellyDrive,Tulsa,Oklahoma 74128.Be
sure and give us the Model Number and Serial Numberof your
SONARINSTRUMENT
25
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

SPECIFICATIONS — LRG-1500A/M INDEX
Operating Frequency.
Pulse Length: (duration of pulse):
Operating Voltage: Minimum
Maximum
Operating Current
1500M
0-18meters
0-120feet 0-30meters
0-360feet 0-60meters
.192 kHz(192000cyclesper
second); accuracy is within
0.6 percent
200-l200ps.
10 volts DC
15volts DC
0.7 to 1.8 amps depending on
printing density and output
power.
.900 wattstypical peak-to-peak
(112watts RMS)
8.5lb. (3.9 Kg)
Instrument Only
Width 9V2"
Height 71/2"
Depth 51/4"
METRIC
Instrument Only
cm Width 24.1 cm
24
Specifications 24
1SOOA
Depth Ranges 0- 60feet
Output Power
Weight
Dimension:
Whatltls
How ItWorks 3
What ItTellsYou 4
" Installation 6
Operation 7
Scale 7
i Sensitivity 7
Suppression 8
Paper Speed 8
Gray Linew 9
How To Read Graphs 10
PaperLoading 13
Stylus Replacement 19
Stylus BeltReplacement 20
Maintenance 22
Do's and Don'ts 23
WithGimbal Mount
Width 121/4"
Height 8%"
Depth 51/4"
METRIC
WithGimbal Mount
Width 31.1
Height 22 cm Height 19 cm
Depth 13.3 cm Depth 13.3 cm
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

WHAT IT IS
'Sonar"isanabbreviation meaning"sound navigation andranging." Itwas
developed asameans oftrackingenemysubmarines during WorldWarII.
Sound—whentransmitted through water — travelsatapproximately4800
feet per second as compared to1100through air.
SOUND TRAVELS
MORE THAN4TIMES
_____
FASTER IN WATER AS IT DOES IN AIR
)DD)flflDflflDflflflfl)
)fl)flfll
Fig,1 4800 FEET PERSECOND IN WATER
Insimple
terms,
anelectrical impulse isconvertedintoasound wave and
transmitted intothewater.Whenthe
wave strikesanobstacle, it rebounds.
Since thespeed ofsound in wateris known — and constant — thetime
betweenthetransmitted signalandthe
receivedechocanbemeasuredand
thedistance totheobstacle determined.Ap electronic sonarunitcan both
send and receivethesoundwaves, aswellastime,measure, and record
them.
PRINCIPLE OFSONAR
TRANSMITTED 1
GNAL
AND RECEIVED I
'ECHO" L((((((((((w((K K K ( (
- ---—- SIGNAL
SENTBYLOCATOR BOUNCES BACK FROM
TARGEt TIME LAPSE INDICATES DISTANCE TO TARGET
Fig,2
The Lowrance Model LRG-1500A/M graph recorder is a compact unit
specifically designed forsport
fishermen. Ithas900Wattstypical peak-to-
peakpower,(112
wattsRMS) features
easy
toreadstraight line recordin'gs,
hasa "gray line"capability, and provides easy-to-read graphs
withsuch
claritythat evenasingle fish hovering just nineinches offthe bottom is
easilyidentified.
Full control of the system is at your finger tips to meet thechanging
demands ofvaryingbottom conditions, waterdepth and boat speed. You
can select the unit'ssensitivity selling, suppression level, depth range,
paperspeed,andthe degree of"grayline"usedtoenhance therecorded
information.Thepatented LowranceVariable
suppression system
not
only
filtersoutfalsesignalswithout
distqrting thereal ones, butissynchronized
Withthe
graylinefunction toprovide)clearsignals underallconditions. The
permanent recordofwhat
your
sonar
has 'seen"isrolled and storedinside
thecase.
2
DOSECTION
Do carry aspare fuse,stylusbelt, and rollofpaper.
Do usethetape fromanew rollorpapertoattach it tothetake-upspool.
Do usethe
empty cardboardcorefromthelast rollofpaper
onthe
take-up
post.
Do carry a pencilto make notes onthepaper.
Do keep therecorded graphs forfuture reference.
Do cleanthe stylusbelt and wheels with alcohol aftereveryfive rolls of
paper.
DON'TSECTION
DON'T OPEN THECASE WHEN THEUNIT ISON.
Don't
pull theplaten assembly down when thestylus is atthe front.
Don't
store anyobjectsinsidethecaseor behind theviewing door.
Don't
forgettotapethe paper to the take-up
core.
Don'trotate thestylusbeltup.
Don'tuseoily cloths, strong solvents orabrasive cleansers.
TROUBLESHOOTING
SYMPTOM WHATTO DO
A. On/Off switch is "ON", but the
stylus and paper don't move
B. On/Off switch is "ON", have
zeromark, butnoechoes orbot-
tomsignals
D. Recordermarksare faintordim D. Cleanviewingdoor;replace the
stylus
E. Recordedmarksareveryheavy;
paperistornby stylus
C. Theunit isON, but paper does
notmove
A. Check fuse; check connections
at battery; tighten powercord
connector
B. Be sure the transducer is plug-
ged intothe unitandthe trans-
ducerisincontactwiththewater
C. Tape Paper tocardboard spool
ontake-up post
E. Bendthe
stylusslightly
toreduce
pressure on paper.
23
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

MAINTENANCE
NOTE: Thestylus may bedamaged ifit isin frontofthe platenwhenthe
platen assemblyispulleddown.Always
movethestylustotheback
sideof
theplatenwhenchangingthe paperrolls.Remembertomovethebeltdown
to remove stylus.
Blackcarbon dustis created during the recording process. Use a soft,
oil-freeragtocleanthe viewingdoorandmetalplatenbehindthepaper.
Low
pressurecompressedairmay
beusedtoblowdustoutofthecaseandaway
from moving partsiftheairis dry and freeofoil.
After every five rolls of paper, the stylusbeltand the wheels it rides on
should be wiped clean withasoftrag moistened with alcohol to remove
carbondust. Strong solvents orabrasive cleaners shouldnot be used.
Allmechanicalconnectionsshould bechecked periodically tobesurethey
haven't worked loose.
DO NOTapply
anytypeof lubricant tothemotorsorgeartrains.
DO NOTwash the unitwithrunning water. Wiping itwith adamp cloth to
remove saltaccumulations, dust, or road grime is allthat'snecessary.
HIGHVOLTAGE
ispresent inthe
transmitter sectionwhen
theunitisON.No
attempt
shouldbemadebyanyunauthorized persontomodifyorrepair
the
electronic section.
Corrosion mayoccuratthe power plug, in thefuseholderorpower cord
splices,
oratthe battery connections.All electrical connections should be
checked periodicallyand cleaned as necessary with400 gritsandpaper.
Thefaceofthetransducer,if mountedonthetransom
should bewashed
periodicallywith mildsoapywaterto
removeany
accumulated roadgrimeor
oily
film. Thisisessentialtohavegoodcontactbetween thetransducerand
thewater.
Periodically,the rubber roller onthepaper
driveshould
becleaned witha
clothdampenedwith alcohol,
toimprove
thefriction
onthedriveshaft. (See
page 16, Figure29).
HOW IT WORKS
When the unit is turned on, an electronically regulated motor drives a
lightweight beltlocatedatthe
rightedgeofthe
recording paper.
Themarking
stylus isattachedtothis belt. Whenthe
stylusisatthe top
ofthepaper, the
transmitter is
triggeredandasmall markismadeatthetopofthe
paper
This
iscalled thezero mark, and represents the surface ofthewater.
22
Thestyluscontinues tomove downtheedge ofthepaper while
thesound
pulse istraveling through the water, and when an echo is detected, the
stylusmakes another mark onthe paper.The depth ofthe object
which
reflectedtheecho canbereadinfeet bycomparing itslocationon
thepaper
tothedepth scale onthe left side oftheviewingarea.
Avariablespeed motordrivesthe
paper
graph.(The paperistreatedsothat
the stylus will burn it to leave a permanent, black mark.) During one
revolution ofthe
stylus belt,averynarrow markwillbemadeby
theflexible
stylus, butthepaper will moveasmall amoiintbefore thenextrevolution.
Eachmarkwillblendintotheonebefore,sothata composite picture"
ofthe
targetwillbe made, onetiny mark atatime. 3
Fish: 17 ft.
eprh: 35 ft. Fig. 3
TRULINE RECORDER BOTH SENDAND RECEIVES SIGNALS.5.
RECEIVED SIGNALS AREINDICATED ONGRAPH PAPER.
PULLEY
DRIVE
-STYLUS
DRIVE
BELT
GRAPH
PAPER
STYLUS
LLEY Fig. 4
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

WI-tAT IT TELLSYOU
Small boat sonar systems are routinely used to measure waterdepth,
examine bottom contours, and locate fish —. but the capability of the
LAG-i
500A/M
goes
far
beyondthe
ordinary.Cluestothe
compositionofthe
bottomare
given
—schoolsofbaitfishareeasilydistinguishedfrom
solitary
game fish — there is a continuous display of information about bottom
contours,submerged shipwrecks— fishasclose
together
assix
incheswill
be
shown separately
—concentrations ofalgae, mossorplankton canbe
identified—attrolling speedsindividual fisharecommonly recordedwitha
characteristic "arched"
signature which distinguishes them fromtheirsur-
roundings — layers
ofwaterwith differenttemperatures canbe detected
undergood conditions, andvertical
movementoffish, (up ordown),canbe
shown.
LOWRANCE STRAIGHTLINE RECORDER
Thisisa
sampl.e
ofthe
graph
printoutby
a
LowranceStraight
LineRecorder.
A and D indicate bottom depths of 16 feet and 46 feet respectively. B
representsanecho (asecond signal)causedfroma
veryhard orreflective
bottomsurface whichcausesthesonarsignaltobounce backtothewater's
surface,
returntothebottom
and reflectbacktothereceiver.Therefore,the
timefor asonar signal totraveltothe bottomandbacktothesurfaOehas
doubled. Ifthetruebottom
reading
islO
feet,the
echowillappearat32feet.
Ifthetruedepthwereten
feet, then theecho would occur20feet. CandE
indicatelargefish.The
thermocline isindicatedat28feet
(G)withschoolsof
baitfish scattered from4feet to20
feet. Itisalso possible toseesmall and
medium sizefishby
their"arched" signatures.Thedarkline acrossthe
top
ofthepapergraph(H) indicates "zero" orthe water'ssurface.
4
4. Grasp the beltatthe stylus holder withthethumbandforefinger
and
move itgently
totheleftwhilepushingthe beltoffthe wheelswiththe
otherforefinger.(SeeFigure 38.)
5. Positionthenew beltonthe
wheels byreversingthe
procedure
used
to
remove theoldone. BESUREthefingersofthenew stylus are pointed
UP.
6. Closethefrontofthecase.Latch both catches onthetopoftheunit.
21
Fig. 5 Fig.38
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

Fig. 35
Figure 37 -- —
\) rvt,1j;;;.
7. Afterinstalling, ifthe
stylus
won't
print allthe waydownthe paper,(See
Figure 37) bend the right leg down so that morepressure isexerted
against
thestainless steelplate. Ifitstill does notprint allthe
way,bend
the leftleg down more (butnot sofarthat itdigsintothe paper).
8. Closethefrontofthe case. Latch both catches onthe
topofthe case.
STYLUS BELTREPLACEMENT
— CAUTION —
High voltageispresentintheelectronicsection when theunitis
turned on.
TURNTHEUNIT OFF.
Release bothcatchesonthe
top
ofthe
case.Pulloutanddownonthe
top
ofthecasefronttoexpose thestylusbelt.
3. Thestylus belt rides over two wheels located atthe rightedge ofthe
platen assembly.RefertoFigure
4onpage 3. Movethefrontofthebelt
DOWN to position thestylusatthe centerofthe platen.
I'
E—"
A. ALGAEAND PLANKTON
B. TRUE BOTTOM SIGNAL
C. SECOND ECHO
TheLRG-1500A/M isacompletesonar. Itscontrols are simple enough for
theoccasional fisherman,andflexibleenough
tosatisfy
themost demand-
ingpro.
We
encourage you
tostudy theremainderofthisbooklettoget
the
mostfrom
yourinvestmentandtoboost
yourboating andfishing pleasure.
BESURE to insertthetwo rubber grommets
on gimbal bracket. Thelarger side (larger
diameter) ofgrommet goes on inside of
gimbal bracket so that itissandwiched
between gimbal
bracket and sonar instru-
ment (see drawings). Thegrommets provide
friction to holdthe unitatthedesired angle.
Fig. 7
20. 5
D. THIRDECHO Fig.6
E. FISH SIGNALS
F. TREES
A -. ,.*B - -. .
B
60' SCALE
b
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

INSTALLATION
MOUNTING
Any
convenientareaissuitableformounting,providing theunitcanbetilted
forthebestviewingangle.Thereareeightmountingholesinthebaseofthe
gimbal bracket for wood screws or thru-bolts. If necessary, a wooden
stiffenercanbeused onthe back
side ofthinfiberglass panels.
If
thedesired mountinglocationiscloserthan18"
toa
magneticcompass, a
trialrunshould bemade, withtheunitin
operation, tobesurethe
compass
readings are notaffected.
POWER CONNECTIONS
12voltDC power forthedepth sounder issupplied fromtheboat's 12 volt
electrical system. Power maybepicked upatanaccessory
orpowerbuss,
butifyouhave problems withelectrical interference (indicated by
extrane-
ousflashesonthe
dial)itcanbeminimizedbyconnecting powerdirectly to
the battery.
Ifa
longerpower
cableisrequired,useordinary#18 lampcord
available at
anyhardware store. Splices should besoldered. Ifthiscan'tbedone, use
crimp-type connectors. Simpletwisting ofsplicesmayresult in intermittent
powerconnections which can causeinterference. Tape all spliceswith
plastic electrical tape.
IMPORTANT NOTICE
When
installingthepowercable, makecertain that thein-linefuse
supplied
with
theunitisattached
tothecenter
conductorofthe
power
cable
asclose
to
the
power
sourceaspossible.
Thiswillprotect
boththeunitandthe
power
cable
incaseeitherisever
shorted. Aconnectorissupplied
toattach the
fusetothe power cable.
Thepositiveconducterinthe
powercableisthe
centerconductor.Theunitis
protected fromaccidental polarity reversals and nodamage
will result if
battery
connections are wrong. (However,
theunitwill notwork.)
STYLUS REPLACEMENT
—CAUTION —
High voltageispresentin theelectronic section when theunitis
turned on.
1. TURNTHEUNIT OFF.
2. Releasebothcatchesonthe
top
of
thecase.Pulloutanddown
onthe
top
ofthecasefrontto exposethe stylus belt. (See Figure34.)
3. Thestylusbeltrides overtwo wheels located attheright edge ofthe
platen assembly. MovethefrontofthebeltDOWNtoposition the
stylus
atthecenterofthe platen.
4. Holdthestylus belt
stationarywith one finger,
and removetheoldstylus
bystarting atits leftedgeandmoving itoutfromunderthetabson
the
stylus holder.
5. Beforeinstalling thenewstylus,besure itisbent
properlybycomparing
itto Figure 35.
6. RefertoFigure36tobesurethenew
stylus
ispositioned correctly under
the
tabs
ontheholder.Besureitmovesfreely
inthetwoslots. If
not, bend
thestylusaway fromtheedge itisrubbingon until itdoesmove freely.
19
L
Fig.8
Ground
(Negative)
Fig.26
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

11. Closethefrontofthe case.
Latchboth catches onthetopofthecase.(See Figure 33.)
12. Turntheunit on.
Move the Chart
Speed knobfully
clockwise. Watch
the paper long
enough to be
sure it is moving
smoothly
and
evenly across the
platen. Ifthe
paperflutters or
begins
to run
up-hill", repeat
Step B.
low
transmitter power
hightransmitter power
hightransmitter power
hightransmitter power
ON/OFFANDSENSITIVITY KNOB— RotatetheOn/Offknobclockwise
toturn
theuniton.TheSensivityknob
worksmuch
likethevolumecontrolon
• a radio,thatis,weaker
signalswill be detected with highersettings
ofthe
knob. When cruising, or at other timeswhenjust simple bottom-contour
information isdesired, theSensitivity setting canbelow. In deepwateror
oversoft, muddy bottoms, (which produce weakechoes), the setting will
have to be higher.
When highSensitivitysettings areused, asecondbottomecho
willappear.
This
isnormal andiscausedby
the
returningsignalreflecting off
thesurface
• ofthewater, making asecond triptothe bottom and back.
Whendetailed information aboutbrush piles, individual fish, orthe
thermo-
dine
is
desired, the Sensitivityknobshouldbesetatabout 3/4point. Refer
totheillustration belowtoseewhat
effecttheSensitivity setting has
onthe
recorded information.
10. Pushthe platen assembly back to its operating position. Be sure it
engages the catch insidethetopofthecase.(SeeFigure 32.) OPERATION
SCALEKNOB — used to
select recording depth. There
are fourpositions:
LRG-1500A
60feet, withlowtransmitter power
60feet, with hightransmitter power
120 feet,with high transmitter power
360 feet, with hightransmitter power
METRIC LRG-1500M
18 meters, with
18 meters, with
30meters, with
60meters, with
Frg.32
Fig.9
18
Fig.33 7
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

Fig.10
Recording individual fish with an "arched"signaturecan usually be ac-
complished attrolling speed withtheSensitivity
knobatthe3/4point, or
higher Refer to the section"Arched Signatures," on page 10 for more
information about thisimportant function ofyourrecorder
SUPPRESSION KNOB — Is used to reduce interference from noise.
Noise, in electronic terms,
isanyundesired signal. Itcanbecaused byan
electrical source, (suchas
the
engine'signition
system), orbyairbubbles in
disturbed waterwhichiscalled cavitation noise. In both cases, thenoise
couldproduce unwanted marks on the paper. (Seepage 11, Figure 18.)
Fortunately noise pulsesarerelativelyshortin
timecomparedtorealsonar
signals. Advancing the Suppression knobwillcause
the system
to reject
theseunwanted,shortpulseswithout
reducing
thesensitivity inanyway.
Thispatented design isexclusivewith Lowrance. However,with highsup-
pression settings, the graph record becomes coarse and the abilityto
separate fish fromthe bottom orfromotherfish will be decreased. (See
page12,Figure
22.)Therefore,the/owerthesuppression settingthebetter
Advance theknob sellingonlyasfarasneccessary toremove the
erratic,
unwanted noise marks. Mostofthe time at low or trolling speeds, no
suppression will be needed.
PAPERSPEED KNOB— Controlsthespeed of
thechart
paperFor
good
detailwhen
trolling
and looking for
fish,orwhen
running
athighspeed,turn
the paperspeed knobup at leasthalf-way. For bestdetail,turnit upto
maximum.Thiswillshow
properfish archesatlow
speeds
andkeeps high
speed information frombeing compressed. (See"Howto Read Graphs.")
8. Draw theend ofthe paper acrossthe faceoftheplaten, aroundthe
friction
roller,overthetake-upcore, andtape itsquarely tothe
take-up
core. (SeeFigure 30.)(Hint: small strips
oftape maybestored inside
housing.)
9. Holdthe
take-upspool,
andturnthe
supplyspool
clockwisetoputasmall
amountoftension onthepaper. Itshouldbe snug against
the platen,
(SeeFigure 31.)
-t
—
SENSITIVITY: ¼SETTING
ONLY THE BOOMSIGNAL
ISDISPLAYED. ALLFISH
SIGNALSARELost
Ag. 30
Fig.11
SENSITIVITY: ¾SETTING
A. TREE
B. THERMOCLINE
c. BAITFISH
SCHOOL
0. GAME FISH
(NOTE:
ELONGATED
ARCHED
SIGNATURES DUETO
VERY SLOWBOAT SPEED)
Fig.31
17
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

6. Removethe
emptysupply corefromtherightsideinthesame manner.
Align
thetwonotches inthecorewiththetabson
the
lowertake-upspool.
(SeeFig. 28) Pushthe paper retainer knob inandrotate ituntil itlocks
into place.
NOTE: Both LPG-602 and LPG-603 chartpaper can beused in this unit.
However, to use the paper core fromthe LPG-602 chart paper on the
take-upside ofthechartdrive, notches mustbecutintothecore. These
notches should be 1/4' wide by 3/16'deep on both sides ofthecore.
LPG-603chart
paper
comeswith thenotchesso nomodification isneces-
sary
when
using
thepapercoreonthe
take-upside ofthepaperdrive. Both
LPG-602 and LPG-603chartpapercanbeused onthe
supplyside ofthe
chart drivewithout modification.
7. Putafresh roll ofpaper inpositiononthecentering posts
ofthepaper
spooi
endcapsonthesupply side (right) oftheplaten assembly.The
papermustspooloffthe bottom oftheroll. (See Figure 29.)
Whencharting
onthe
360scalein
deepwater,thepaperspeed should be
turned downtonomorethan half-wayfor thebestrecord. Ifgaps appear
betweenstylus strikes,
thepaperisrunningtoofast.Thepaperspeed may
also beturneddown toconserve paper
whennotlookingforfishorcon-
cerned
withfinedetail.
— -s' '—"
/ * .
i—: ''
GRAY LINE ON/OFF KNOB— The Gray Linefunction canbe used to
outline thebottom contourwhichmightotherwise behiddenbeneathtrees
and brush; itcanalso give clues tothecomposition ofthebottom. Ahard
bottom returns averystrongsignalcausing awidegray line.Asoft,muddy
or
weedy
bottomreturnsaweakersignal
whichisemphasizedwithanarrow
gray
line. Do notadvance thecontroltoofaroritwillgray lineonfish,trees,
etc.Inwater less than 30', justclick theknob on"— donotadvance the
control knob.
WI'' j
£
'
1'
ft
' lTi
:
BOULDERS/LARGE
Rocks Hg.12
GRAY-LINE: 'OFF"
Fig.28
BOULDERS/LARGE
RocKs Fig.13
GRAY-LINE: 'ON"
GRAY-LINE: 'OFF"
A. FISH
B. TREES
c. FISHIN TREES
D. BAIT FISHSCHOOL
Fig.14 GRAY-LINE: 'ON"
A. FISH
B. TREES
c. FISH IN TREES
D. BAIT FISH SCHOOL
Fig.15
Fig.29 Arrowindicates friction roller
16 9
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

HOWTO READGRAPHS
"ARCHED SIGNATURES" —Aremarkable advantage ofthe LRG-1500
A/M isthat itcanrecord individual fish withacharacteristic arched mark
that separates them fromtheir stationary surroundings. Thereason for
this isshown below. Thedistanceto
afishwhenitmoves intothesonar's cone of
sound is shown as "A' in thedrawing. When
thefish hasmoved tothecenterofthe cone,
thedistanceto itwill beshorter, (line"B"),
andas it moves outofthe cone, thedistance
willincrease again asshown in line "C".
Ifapartial arch occurs mostofthe
timeon yourunit (the mark curves
upbut does notcurve backdown), it
is because thetransducer is not
aimed straightdown.
Sharp, well-defined signatures willoccurmostoftenwhenthe Sensitivity
knobissetatthe3/4point
orhigher.(See(C), Figure 17.)Remember,too,
thattheremustbesomemovementbetween thefishand boattodevelop
the arched mark.
Fig.17
THERMOCLINES
— The temperature of water in the lake is seldom
constant from
top
tobottom. Layersofdifferent
temperaturesform,
andthe
junction
ofawarmandcoollayer ofwateriscalledathermocline.The
depth
and thickness ofthethermocline canvary
withtheseasonortime
of
day.In
deep lakestheremay
betwoormore,atdifferent
depths. Thermoclines are
important to thefisherman because theyareareas whichfish are active.
Manytimesbaitfishwill beabove thethermocline whilelarger game fish
suspend justbelow it. (See(G), Figure 17.)
YourLowrance Model LIRG-1500&/Mcandetectthis invisible layerin the
water,buttheSensitivity knobwillprobably
havetobesetatthe3/4
point,or
higher.
10
5. Toremovethefull take-up roll,push inandrotatetheleftpaper retainer
knobuntil itsnapsout. (See Figure 26.) The roll can now be easily
removedfromthe paper spool end caps. (SeeFigure 27.)
w
Fig. 16
30 —
40 —
50 —
60 —
Hg.27
15
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

3. Move thestylusbelt DOWN, (on theright side oftheviewingarea), to
positionthemarkingstylus
onthebacksideci
theplaten.NEVER
move
the beltup — the stylusmaybedamaged.
SPECIALNOTE:
The stylus may be damaged litheplaten assembly is
pulleddownunlessthe
stylushas
beenmoved
tothebacksideofthe
platen.
4. Pulloutanddown
onthetabatthe
top, center
ofthe
platenassembly
to
expose
the paper spools. (SeeFigure25.)
Fig.25
14
rrt
1' 7-;;t
— -
Fig.18
A. JIGGINGA 1¾oz. HOPKINS
SPOON INSUBMERGED THEE.
B. FISH SIGNALS (BOATDRIFTING
VERY SLOWLY OVER FISH)
C. BAITFISH
Fig.20 I
rrv'
High Speed (46 MPH.)
SUPPRESSION: ON— ADEQUATE SETTING
SENSITIVITY: ON— 1/2POSITION
SCALE:0TO60 FEET
PAPER SPEED: SLOW
SUPPRESSION: OFF
DEPTHS: RECORDED FROM 18
INCHES TO71/2FEET
t?.
11
High Speed (46 M.P.H.)
SUPPRESSION: OFF
SENSITIVITY: ON —1/2 POSITION
NOTE POOR RECORD CAUSED
BY NOTUSING SUPPRESSION
WHENATHIGH SPEED.
GRAY-LINE: "OFF"
A. FISH ONORNEAR BOTTOM
t::r—-'
GRAY-LINE: 'ON"
A. FISKONORNEARBOTTOM
PDF compression, OCR, web-optimization with CVISION's PdfCompressor

-. PAPERLOADING
1. TURNTHEUNIT OFF.
Li
I
4
1
pt\ Afl\pr
2._ ,— r
-.
A. AFISH SUSPENDED UNDER BOAT
B. FISH
SWIMMING UP
TOWARDS BOAT
C. SCHOOLOFBAIT FISH
D. SURFACE CLUTrER
SCALE:0 TO60 FEET
GRAY-LINE: 'OFF"
— CAUTION —
High voltage ispresentin theelectronicsection when theunitis
turnedon.
2. Release both
catchesonthe
top
ofthe
case.Pulloutanddownonthetop
ofthecasefrontto exposethe platen assembly. (SeeFigure24.)
4 Fy23
Fig.21
A. FISH DRIFTING UNDER BOAT.
FISH MOVED FROM 13½FEET
TO21 FEETTO12 FEET
WHILE
DRIFTING/SWIMMING WITHIN
THECONE OFSOUND.
B. JIGGING ALEAD-HEADLURE
OFFBOTrOM.
SCALE:0TO60FEET
GRAY-LINE: "ON"
V
- - Fig.22
SUPPRESSION: TOO HIGH
(NOTE THAT RECORDER SIGNALS
FROM
SCHOOLS OFBAITFISH AREELON-
GATED ANDRUNTOGETHER WITH THE
BOnOM.)
I
SUPPRESSION: PROPER SETTiNG
(NOTE
DISTINCT INDIVIDUAL
SCHOOLS OFBAIT FISH.) q -. _i
END-OF-PAPER MARKER
—The
graphpaper
used inthe
LRG-1500A/M
hasared lineprinted
atthebottom
ofthe
paper
tosignify when
there isonly
2to3feet before theend ofthepaper(See Figure 23on Page 13.)
Fig.24
13
PDF compression, OCR, web-optimization with CVISION's PdfCompressor