Sinclair ZX User manual

SERVICINGMANUAL
FOR
ZXPRINTER
.LISTOFCONTENTS
INTRODUCTION
SECTION1 GENERALINFORMATION
SECTION2 SYSTEMDESCRIPTION
SECTION3 FAULTDIAGNOSISANDREPAIR
SECTION4 REMOVALANDINSTALLATIONPROCEDURES
SECTION5 ILLUSTRATIONS
-LISTOFILLUSTRATIONS
FigNo.
1
2
3
4
5
6
7
LocationofComponents
LocationofComponents
TopCoverandBaseInsertAttachmentPoints
Setting-UpDriveTrain
PinchRollerSprings
LogicCircuitDiagram
CircuitDiagram
©SinclairResearchLtd.
(i)

SERVICINGMANUAL
FOR
ZXPRINTER
-INTRODUCTION-
ThismanualisforusebyauthorisedSinclair
dealers,engineersandrepresentativesasa guide
torectifyingfaultsontheSinclairZXPrinter.
Repair/renewalproceduresarelimitedtothose
which are specific to this printer; standard
proceduresfortherenewalofelectronic
componentsetc.,arenotincluded.
NOTE: The printer uses electro-sensitive
paper,thegradingandqualityof
which are critical if satisfactory
operationoftheprinteristobe
achieved.Onlypaperwhichis
suppliedandapprovedbySinclair
ResearchLtd.,ortheiragentsshould
beused.Ifadjustmentsaremadein
an attempt to make the printer
functionwithotherpapers,excessive
wearoftheprintermechanismmay
result.
(11)

SAFETYMEASURES
1.Thisinstructionmanualcontainscertain
WARNINGandCAUTION
noticeswhichMUSTbefollowedbytheuserto
ensureSAFEoperationandtoretainthe
equipmentina SAFEcondition.
2.Allusersoftheequipmentdescribedinthis
manualMUSThavereceivedadequatetraining
initsuseandapplicationinordertoensure
SAFEANDPROPERUSE.
3.Anyadjustment,maintenanceandrepairofthe
openedapparatusundervoltageshallbe
carriedoutonlybya skilledpersonwhois
AWAREOFTHEHAZARDINVOLVED.

SECTION1
GENERALINFORMATION
Sub-SectionLISTOFCONTENTSPageNo.
1Introduction1.1
2PrincipleofOperation1.1
1.INTRODUCTION
1.1TheZXPrinterisdesignedforusewiththeSinclairrangeofmicro-
computers,andprovidesa permanentrecordofanycomputeroutput
whichmaybedisplayedontheTVscreen.Becauseofgraphicdisplays
always'joinup',longprograms,tablesofresults,elaboratepatterns
andgraphscanbeprintedoutascontinuousrecords,evenifcarried
outinseveralparts.
2.PRINCIPLEOFOPERATION
2.1Theprintingmechanismisunconventional,andconsistsoftwostyli
whichpasssuccessivelyacrossthesurfaceofthepaper.Eachpass
representsonerowofdots,andsixrowsofdotsformthematrixfora
singlelineofprint.A moderatelyhighvoltage(50V)isgeneratedin
theelectronicswithintheprinter,andisroutedtoa conductorstrip
inthetopcover.
2.2Eachstylusishairpin-shapedsothatoneendpassesoverthesurface
ofthepaperwhilsttheotherendcontactstheconductorstrip,thus
carryingthecurrenttothenatalliecoatingofthepaper.Thereturn
pathisthroughthecoatingtotheconductiverubberroller,which
alsofeedsthepaperthroughtheprinter,totheearthconnections
withintheelectroniccircuitry.Beforemakingcontactwiththe
paper,thestyluspassesoveran'L'-shapedinsulatingwafer;asthe
stylusleavesthewafer,ittouchesthepaperandtheelectrical
continuityissensedbythecontrolelectronicswhichthenpulsesthe
appliedvoltagetoprovidetheprintingaction.
2.3A descriptionofthecontrolcircuitisgiveninSection2.
1.1

SECTION2
SYSTEMDESCRIPTION
Sub-Section LIST OF CONTENTS Page No.
1Introduction2.1
2TopCoverAssembly2.1
3BeltandStyli Assembly2.1
4MotorandGearTrainAssembly2.2
5ControlElectronicsBoard2.2
6BaseFrameAssembly2.2
7PaperReelCarrierAssembly2.2
8LogicDescription2.3
9CircuitDescription2.3
1.INTRODUCTION
Theprintercomprisessixmainassemblies(seeFigures1 and2):
(a)TopCoverAssembly,
(b)BeltAssembly,
(c)MotorandGearTrainAssembly,
(d)ControlElectonics,LoomandEdge-ConnectorAssembly,
(e)BaseFrameAssembly,
(f)PaperReelCarrierAssembly.
2.TOPCOVERASSEMBLY
2.1Thetopcoverassemblyconsistsofa mouldedplasticcover,a metal
conductor strip, anda serratedplastic strip which forms a cutting
edgetofacilitatetearingoffthepaperprintout.Twobushesare
mouldedintotheundersideofthecovertohousetheupperendsofthe
driveandidlerpulleyshafts.Theassemblyissecuredtothebase
frame by four screws which are inserted from the underside ofthe base
(seeFigure3).
3.BELTANDSTYLI ASSEMBLY
3.1Thisassemblycomprisesanendless,internally-toothedplasticbeltto
which are attached two hair-pin styli. Each stylus fits over a spigot
onthe upper edge ofthe belt, andis retained bya push-on cap. The
beltislocatedontwosimilarpulleys,oneofwhichisdrivenbythe
motor via bevel gearing,while the other isan idler.
2.1

4.MOTORANDGEARTRAINASSEMBLY
4.1Themotorandgeartrainassemblydrivesthefollowing:
(a)beltassembly,whichproducestheprintoutimage,
(b) paperfeed roller, which moves the paper upwards as printing
proceeds,
(c)encodingdisc,whichfunctionsinconjunctionwiththecontrol
electronicsp.c.boardtoprovidetheprintoutsignalstothe
stylf onthebeltassembly.
4.2Thehorizontallymountedmotordrives,viabevelgearing,the
vertically mounted pulley and wormshaft which rotates the belt
assembly.Thiswormshaftdrivesa horizontallymountedwormshaft
which,inturn,drivesthepaperfeedrollerassembly.Atthelower
endofthepulleyandwormshaft,a spurgeardrivestheencoderdisc,
bothitemsbeingmountedwithintheundersideofthebaseframe.
5.CONTROLELECTRONICSBOARD
5.1Thecontrolelectronicsboardismountedontheuppersurfaceof
thebaseframe.Inconjunctionwiththeencodingdiscandthe
LED/photodiodecombination,theboardprovidessignalstodrivethe
motorandtheprintingsystem.Thep.c.boardisconnectedto
thedouble-sidededge-connectorbya shortloom;thep.c.board-end
oftheloomisclampedbetweenthetopcoverandthebaseframewhen
thecoverissecuredtothebase.
6.BASEFRAMEASSEMBLY
6.1Thebaseframeassemblycomprisesthebaseframeandthebaseframe
insert, both of which are plastic mouldings. The base frame provides
a chassis on which most components are mounted; the base frame insert
isa removablesectionwhichfitsintotheundersideofthebase
frame.Theinsertcontainsthelowerbushesfortheshaftsofthe
drive and idler pulleys, as well asthe mounting forthe LED. Itis
securedtothebaseframebytwoofthefourscrewswhichretainthe
topcover,andbytwoshorterscrews(seeFigure3).
7.PAPERREELCARRIERASSEMBLY
7.1Thepaperreelcarrierassemblyconsistsofa plasitcmouldingwhich
housesthereelofelectro-sinsitivepaper,anda spring-loadedpinch
roller.Thepaperissupportedinthecarrierontwoplastic
spigotted end-caps which are inserted into the ends ofthe tube atthe
centreofthereel; theseend-capsshouldbetransferredtothenew
reel when the reel is changed. The spring-loadedpinch roller forces
the paper into contact with the paperfeed roller to provide the
'grip'necessarytoenablethepapertobefedthroughtheprinter.
The complete assembly slides into the base frame, and clips into
place;itisreleasedbypressurebeingappliedtothepointmarked
PRESS HERE onthe underside ofthe carrier.
2.2

7.2Normally,thepaperfeedsthroughtheprinterasprintingtakesplace.
However, a manually operatedpaperfeedswitch is fitted to enable the
papertobefedthroughwithoutprinting,forexample,toprovidea
tear-offmarginattheendofa print-out.Theoperatingbuttonfor
thisswitchprotrudesthroughthetopcover.
8.LOGICDESCRIPTION
8.1TheLEDandthephotodiodearepositionedonoppositesidesofan
aperturedencoder disc. Asthe disc rotates, the beam of light from
theLEDisinterrupted,thusprovidinga pulsedsignal,thetimingof
whichisgovernedbythespeedofrotationofthedisc.This,pulsed
signalisappliedtooneinputofanAND-gatewhose1outPut1S
connected,viaa divide-by-fourcircuit,toa blockinputofa buffer
storeanddecoder(seeFigure6).
8.2Thebufferstoreanddecoderreceivesandstoresinformationrelating
toone line of print, i.e. six scanned lines, from the computer; it
respondstoclockpulsesatitsclockinputtoselectivelyenablethe
high-voltage(50V)switchtopermitcurrenttoflowfromthepower
supply tothe conductor strip and thence, viathe stylus tothe paper.
Thecircuitisearthedviatheconductingrubberrollerofthepaper
feed anda resistor. Where the50Vis applied tothe surface ofthe
paper,themetalliccoatingisburnedoff,leavingthedark
undercoatingexposedtoprovidethepermanentimage.Theconductor
strip is alsoconnected tothe paper detect circuit which detects when
thestylushasrunofftheedgeoftheinsulatingwaferandhas
commencedtrackingacrossthesurfaceofthepaper.
8.3Theencoderdiscproduces1024pulsesacrosstheprintingwidthofthe
paper;theseareproducedto256bythedivide-by-fourcircuitto
ensurethattheregisterofeachlineofdotswithinthematrixis
maintainedtowithina quarterofthewidthofa dot.
9.CIRCUITDESCRIPTION
9.1TR1andTR2 form a self regulating 50V power supply. The50Vmaybe
measuredconvenientlyonC4(seeFigure7).
9.2 When the stylus first makes contactwith the paper atthe left hand
margin,TR5isswitchedonviaR8.Thisraisesthelevelatpin4 of
theULAandresultsintheencodersignalbeingpassedtothe
associatedmicrocomputer.C6andRllpreventcontactbeinglost
momentarily andare critical in value. Many problemshavebeen
experiencedwithdevicesgivingtoomuchgainandTR5whichonsome
early printers wasa ZTX550 should be replaced bya ZTX551.
9.3TR3andTR4switchthe50Vtothestylusinordertogenerate
printing.
2.3

9.4ThephototransistorTR9issolderedtotheboard,whiletheLEDison
flyingleadsstuckintothebaseinsert.Theseitemsaresubjecttoa
lotoftolerancesbutthereshouldbegreaterthan200mVp-patpin2
oftheULAwhenoperating.Commonfaultsencounteredinclude,over-
etchedencoderdisc,encoderdiscworkingloose,incorrectlyformed
slotm thebaseframeinfrontofthephototransistor(somehave
metalshimswithphoto-etchedslots). Dirtintheencoderdiscorin
frontofthephototransistoralsogivemisleadingresults.The
operationoftransistorTR9canbereadilycheckedusingan
oscilloscopeprobeontheemitter.
9.5TransistorTR6switchesthemotoronandoff.Duringthelasttwo
linesofan'Lprint'themotorrunsslowly;thisisaccomplishedby
switchingTR6onandoff,usingthetimeconstantR13/C8in
conjunctionwiththephototransistoroutput.
9.6Themotorisfittedinternallywitha vanstorringsuppressor.
Withoutthisitwouldgeneratesomuchinterferencetomakeit
unusable.Itisunlikely,however,thatthiswouldoccur.
2.4

SECTION3
FAULTDIAGNOSISANDREPAIR
Thefollowingtableisintendedasa generalguidetothediagnosis
andrectificationofmostofthefaultswhichmayoccurafter
considerableusageoftheprinter.
FAULTPOSSIBLECAUSEREMEDY
1.Poorprintquality:
(a)Verticalzig-zag(a)Wornbelt.(a)Fitnewbelt.
usuallyworseon
right-handside.
(b)Horizontallines(b)Wornbelt.(b)Fitnewbelt.
unevenlyspaced.
(c)Printfadingout(c)Dirtonconductor(c)Cleanand
overpartoflinestripintoplubricate
cover.conductorstrip-
useElectrolube.
(d)'Noisy'Printin5-<d)W Excessive(d)/^FitZTX551in
gainonTR5.placeof
ZTX550
(ii)Insufficient(ii)FitnewULA.
signalfrom
encoder.
2.Noprint:(a)Ifprintisall(a)Ifdefective,
black,checkTR4.changeTR4.
(b)Ifnoimage,check(b)Connectwhitewire
thatwhitewiretoconductorstrip
isconnectedtoandcheck50Vis
conductorstrip.presentonstrip.
(c)Dirtonphoto-(c)Cleanphotodiode
diodeand/orLED.and/orLED.
{d}Defectivephoto-(d)Fitnewphotodiode
diodeand/orLED.and/orLED.
3.1

FAULTPOSSIBLECAUSEREMEDY
3. Motor not operating: (a) Conductor strip (a)Fitnewtop cover
hasbecomelooseassembly.
Intopcover.
(b)Motorbevel(b)Checktightnessof
piniontouchingscrewsandreset
motormountinggearmesh(see
screws.Figure4).
4.Motorrunning(a)Excessive(a)Slightlyslacken
slowly:frictiononbaseinsertscrew
encoderdisc.nearencoderdisc.
(b)Excessivegain(b)FitZTX551in
onTR5 place of ZTX550.
5.Inadequatepaper(a)Insufficient(a)Fitnew0.60mm
feed:springpressuredia.springs.
onpaperpinch
roller.
(b)Paperreelends(b)Ensurethatreel
jammed against is wound tightly
thecover.andnottouching
cover.

SECTION4
REMOVAL ANDINSTALLATIONPROCEDURES
Sub-SectionLISTOFCONTENTSPageNo.
1CleaningandLubrication4.1
2TopCoverAssembly4.1
3BeltandSty!i Assembly4.2
4MotorandGearTrainAssembly4.3
5PCBoard,LoomandEdgeConnectorAssembly4.4
6EncoderDisc4.5
7PaperFeedRollerAssembly' 4.6
8PaperReelCarrierPinchRollerSprings4.7
1.CLEANINGANDLUBRICATION
1.1A certainamountofdustfromthemetallizedcoatingofthepaperwill
accumulatewithintheprinterasprintingproceeds.Wheneverthe
printerisdismantledforanyreason,thedustshouldberemoved,
usinga gentleairblastand/ora softbrush.
-CAUTION
Neverusesolventsorotherfluidsasthey
may attack the plastic or rubber components
1.2Beforere-assemblyoftheprinter,bushesshouldbelightlylubricated
withMolycote44,butgears,wormshaftsetc.,mustnotbelubricated;
athincoatingofelectrolubeshouldbeappliedtotheconductorstrip
inthetopcoverassembly.
2.TOPCOVERASSEMBLY
2.1Toremovethetopcoverassembly:
(a) Remove the paper reel carrier assembly.
(b)Removethefourscrewsatthecornersofthebase(seeFigure3).
(c)Liftthecoverapproximately15mm,removethewhitewire
connector from the spadeterminal onthe conductor strip inthe
undersideofthecover.
(d) Withdraw the cover, and lift offthe operatingbutton forthe
buttonfeedswitch.
4.1

(e)Iftheserratedtear-stripiswornordamaged,thiscanbe
removedbypushingoutthecentrelug(nearthespadeterminal),
liftingtheouteredgesofthetear-stripandmovingitawayfrom
thecovertodisengagetheretaininglugsfromtheslotsinthe
cover.
2.2Toinstallthetopcoverassembly:
(a)Ifa newtear-stripistobefitted,insertitsretaininglugs
intotheslotsinthetopcover,andpushdownonthetear-strip
untilitclipsintoposition;ensurethatthecentrelugis
engagedinitsslotinthecover.
(b)Positionthebeltassemblyonitspulleyssothatthestyliare
attheextremeleftandrightoftheprinter,thatis,theyare
onthepulleys.Ensurethatthestyliareinthetrailing
position- thebeltrotatesclockwise,viewedfromthetop.
(c)Placetheoperatingbuttononthespigotofthepaperfeed
switch,andensurethattheslopingfaceofthebuttonis
correctlyalignedwiththecontourofthetopcover.
(d)Placethetopcoverinposition,andconnectthewhitewireto
thespadeterminalontheconductorstrip.
(e)Gentlymanoeuvrethetopcoverintoposition,ensuringthatboth
pulleyshaftsengagetheirlocatingbushes,andthatthepaper
feedswitchoperatingbuttonlocatescorrectlyonthecut-outin
thetopcover.Checkthatthewirestotheswitcharenotcaught
betweenthecoverandthebaseframe.
NOTE:Careisneededtoavoiddamagetotheinsulatorstripon
theverticalwebofthebaseframe.
(f)Securethetopcovertothebaseframewiththefourscrews.
(g)Fitthepaperreelcarrierassembly.
3.BELTANDSIYLIASSEMBLY
3.1Toremovethebeltandstyliassembly:
(a)Removetopcoverassembly(seepara2.1).
(b)Liftoffthebeltandstyliassemblyfromthepulleys.
(c)Ifitisdesiredtoremovea stylus,pulloffthestylus
retainingcap,andliftthestylusfromitsmountingspigoton
thebelt.
4.2

3.2Toinstallthebeltandstyliassembly:
(a)ifa stylushasbeenremoved,placea newstylusoverits
mountingspigotonthe,belt.so,thatthelegofthestylus.which
hasthelonger'foot11Soutsidetliebelt-,securetliestYlus°?
pushingtheretainercapontothespigot.
(b)Placethebeltassemblyoverthepulleyssothatthestyliareat
theouteredgesofthepulleys,andthestyliareinthetrailing
positiononthebelt- thebeltrotatesina clockwisedirection,
viewedfromthetop.
{c}Installthetopcoverassembly(seepara2.2).
4.MOTORANDGEARTRAINASSEMBLY
4.1Toremovemotorandgeartrainassembly:
(a)Removetopcoverassembly(seepara2.1).
(b)Removebeltandstyliassemblyandidlerpulley(seepara3.1).
(c)Removethedrivepulleybypullingitupwards(itsshaftisa
pushfitinthelargespurgearwithinthebaseframe).
(d)Prisethewormshaftoutofitssupports,andremoveit.
(e)Prisethebevelpinionfromthemotorshaft,andremovethe
spacerfromtheshaft(iffitted).
(f)Unsolderthewiresfromthemotorterminals.
(g)Removethetwoscrewssecuringthemotortoitsmounting,and
withdrawthemotor.
NOTE:Onearlierprinters,themotorislightlygluedtoits
mounting,anditwillbenecessarytoprisethemapart
carefully.
4.2Toinstallmotorandgeartrainassembly:
Priortoinstallingthemotor,determinewhetherthebaseframeisof
theearlypatternorthelaterdesign.Ontheearlypattern,thereis
across-shapedslotinthemotormountingflange;thelaterdesignhas
averticalslotonly.
(a)Iftheprinterisoftheearlytype,applya thincoatof
suitableglue,suchasLoctite,tothefaceofthemotor.
4.3

(b)Positionthemotoronitsmountingflangewiththeorientation
mark(ontheterminalendofthemotor)attheoutside,and
insertthetwoattachmentscrews.Iftheprinterisofthelater
design,thescrewsmaybetightenedfullyatthisstage.Ifthe
printeris of theearlierpattern,theverticalheightof the
motormustbesetasshowninFigure4;itmaybeadvantageousto
manufacturethejigshowninFigure4 toensureaccuratesetting
ofthemotorbeforethescrewsaretightened.
(c)Fitthespacertothemotorshaft,andpushthebevelpinion
fullyontotheshaft.
NOTE:Onsomemotors,theendbearingisrecessedonitsouter
face.Thespacerforusewiththismotoris3.25mmlong,
whereasthespacerforusewiththeflush-facedend
bearingis2.92mmlong.Itisessentialtoensurethat
thecorrectspacerisfitted.
Ifa spacerisnotavailable,setthebevelpinionclearanceas
showninFigure4.
(d)Solderthewirestothemotorterminals- theredwireconnects
totheouterterminal,theblackwiretotheinnerterminal.
EnsurethatcapacitorC9isconnectedacrossthemotorterminals.
NOTE:Theblackwiremustpassoverthewhitewirewhich
connectstotheconductorstripinthetopcover.
(e)LightlylubricatetheendsofthewormshaftwithMolycote44,and
presstheshaftintoitssupportbushes.
(f)Supportthebaseinsertinthevicinityofthelargespurgear,
andpushthedrivepulleyshaftfullyhomeintothespurgear
bosswhichprotrudesupwardsthroughthebaseframe.
(g)Fittheidlerpulleyandbeltassembly.
(h)Fitthetopcoverassembly(seepara2.2).
5.PCBOARD,LOOMANDEDGECONNECTOR
5.1Toremovethep.c.board,loomandedge-connectorassembly:
(a)Removethetopcoverassembly(seepara2.1).
(b)Removethemotor(seepara4.1).
(c)Disconnectthegreenwireattheearthterminal.
(d)Removethetwoscrewssecuringthebaseinsert,andeaseitclear
ofthebaseframe.CarefullyeasetheLEDanditsleadsoutof
themountingclipsonthebaseinsert,andremovetheinsert.
4.4

(e)Removethetwoscrewssecuringthep.c.boardtothebaseframe.
(f)Gentlyeasethephotodiodeanditsleadsoutofthemounting
clipsonthebaseframe,andremovethep.c.board,loom,and
edge-connectorassembly- takecaretoavoiddamagetotheLED,
photodiodeandtheirleads.
5.2Toinstallp.c.board,loomandedge-connectorassembly:
(a)Carefullypositionthep.c.boardonthebaseframe,withtheLED
anditsleadspassingthroughthecut-outinthebaseframe.
(b)Clipthephotodiodeanditsleadsintoplaceonthe'baseframe
(ensuringthatthelensisfacingdownwards),andsecurethe
p.c.boardtothebaseframewithitstwoscrews.
(c)CarefullyinserttheLEDanditsleadsintotheclipsonthebase
insert,ensuringthatthelensfacesupwards.
(d)Securethebaseinserttothebaseframewithitstwoscrews.
(e)Connectthegreenwiretotheearthterminal.
(f)Installthemotor(seepara4.2).
(g)Installthetopcoverassembly(seepara2.2).
6.ENCODERDISC
6.1Toremovetheencoderdisc:
(a)Removethescrewssecuringthebaseinsert,andeasetheinsert
outofthebaseframe.
NOTE:AvoiddamagingtheLEDanditsleadswhichareclippedto
thebaseinsert.
(b)Carefullylifttheedgeoftheencoderdiscuntilitsspindleis
clearofthebushinthebaseframe,andslidethediscclear.It
isnotnecessarytoremovethelargespurgearwhichdrivesthe
encoderdisc.
6.2Toinstalltheencoderdisc:
(a)Applya traceofMolycote44tothebushfortheencoderdisc
spindle.
4.5

(b)Ensurethattheencoderdiscisclean,andcarefullyslideits
edgeunderthelargespurgearuntilthespiondlecanbeseated
initsbush.
NOTE: Laterversions ofthe printer have a modifiedspurgear
ontheencoderdiscanda flatspringfittedtothe
spindle,abovethespurgear.Theseverionsare
identifiedbythepalebluecolourofthesmallspurgear
(theearlierversionsarewhite).Thismodifiedgearand
flatspringcanonlybefittedtothelaterversionof
thebaseinsert- theymustNOTbefittedtotheearlier
versions.
(c)Carefullyfitthebaseinsertintothebaseframe,andsecureit
withitsscrews;avoiddamagetotheLEDanditsleads.
7.PAPERFEEDROLLERASSEMBLY
7.1Toremovethepaperfeedrollerassembly:
(a)Removethetopcoverassembly(seepara2.1).
(b)Disconnectthegreenwirefromtheearthterminal.
(c)Removethescrew,washerandnutwhichsecuretheearthterminal
tothebaseframe,andwithdrawtheterminal.
(d)Slidethepaperfeedrollerassemblysidewaysuntilitsend
disengages from its worm wheel, and withdraw the roller assembly.
7.2To install the paper feed roller assembly:
(a)Inserttheroundendofthepaperfeedrollerassemblyintoits
mountinginthebaseframe.
(b) Slide the square endofthe roller assembly into the worm wheel,
andpushitfullyhome.
(c)Securetheearthterminaltothebaseframewiththescrew,
washerandnut,andensurethattheterminalcontactstheendof
therollerspindle.
(d)Connectthegreenwiretotheearthterminal.
(e)Installthetopcoverassembly(seepara2.2).
4.6

8.PAPERREELCARRIERPINCHROLLERSPRINGS
Aspringisfittedateachendofthepaperreelcarriertoforcethe
pinchrollerintocontactwiththepaper.Althoughthespringsare
identical,theymustbefittedinthecorrectmanner(seeFigure5)-
alwaysremoveandinstallonespringata time.Earlyprintersare
fitted withsprings made from 0.55 mm diameterwire; later printers
are fitted withsprings made from 0.60 mm diameterwire. Whenever
thesespringsaretobechanged,thethickerspringsshouldbefitted,
regardlessofwhethertheprinterisanearlyorlaterversion.

SECTION5
ILLUSTRATIONS
LISTOFCONTENTSFigNo.
LocationofComponents(1)1
LocationofComponents(2)2
TopCoverandBaseInsertAttachmentPoints3
Setting Up Drive (Gear) Train 4
PinchRollerSprings5
LogicCircuitDiagram6
CircuitDiagram7
5.1