Ampex 601 Manual

tm iooi
I AMI
EX
^ ^MiDEL601
Operation
Maintenance
^Mannal
AiMPEX
CORPORATION
.•14CHARTER STREET
BEWOODCITY • CALm>BMA

TM lOOl
AMI
>
EX
MODEL 601
Operation
Viaintenance
Manual
^^^^^^^
^^^^^^^^^^^^^^^^^^^^
^^^^^^^^^^^^
^^^^^^^^^^^^^^^^^^^
^^^^^^^^^^^^^^^^
AMPEX
CORPORATION
934CHARTER STREET
REDWOOD CITY - CALIFORNIA

3rd EDITION
OCTOBER 1958
TableofContents
Page
I. DESCRIPTION AND SPECIFICATIONS I-l
GENERAL 1-1
SPECIFICATIONS 1-2
n. PRINCIPLES OF OPERATION 2-1
THEORY 2-1
HI. INSTALLATIONANDOPERATION 3-1
GENERAL 3-1
POWER 3-1
LINE INPUT 3-1
MICROPHONE INPUT 3-1
REPRODUCEOUTPUT 3-1
INTERCONNECTING 3-2
CONNECTORS 3-2
STUDIOINSTALLATION 3-2
TAPETHREADING 3-3
RECORDING WITH HALFTRACKMACHINES 3-4
REPRODUCING WITH HALFTRACKMACHINES 3-4
RECORDING 3-4
REPRODUCING 3-5
REWIND AND FAST FORWARD 3-5
ERASING 3-5
MIXING 3-5
SYNTHETICREVERBERATIONS 3-6
IV. TAPETRANSPORTASSEMBLY 4-1
GENERAL 4-1
STAND-BYOPERATION 4-1
PLAYMODE 4-1
REWIND MODE 4-3
FAST FORWARDMODE 4-3
ROUTINE MAINTENANCE 4-4
V. ELECTRONICASSEMBLY 5-1
GENERAL 5-1
RECORDCHANNEL 5-1
REPRODUCECHANNEL 5-1
BIAS AND ERASE OSCILLATOR 5-1
ELECTRONICALIGNMENT 5-2
ALIGNMENT AND TEST EQUIPMENTREQUIREMENTS 5-2
VI. PARTS LIST 6-1,
ListofIllustrations
Fig. No.Caption Page
FRONTISPIECE
2-1 TAPEMAGNETIZATION 2-1
2-2 RECORDINGHEAD 2-2
2-3 MAGNETIZATIONCURVE 2-3
2-4 OUTPUT VS. FREQUENCY 2-4
2-5 ACHIEVINGFLAT RESPONSE 2-5
3-1 SPACE REQUIREMENTS 3-2
3-2 TAPETHREADINGANDNOMENCLATURE 3-3
4- 1 MECHANICALOPERATIONSIMPLIFIED 4-2
4-2 ROUTINELUBRICATION 4-3
4-3 TAPETENSIONMEASUREMENTS 4-5
4-4 TAPETRANSPORTEXPLODEDVIEW
5-1 REPRODUCEAMPLIFIER RESPONSE 5-4
5-2 RECORDAMPLIFIER RESPONSE 5-7
5-3 SCHEMATICDIAGRAM

I.Description& Specifications
TheAMPEXModel 601isa lightweight,portable,magnetictapeGENERAL
recorderdesigned for professionaluse, andis available inany combina-
tion of theseversions:
Power Input 117 volts, 50or60 cycles
persecond (cps)
Tape Speed IY2 or 3 -M inches per
seconds (ips)
Head Assembly full or halftrack
Anaccessorytransformer(CatalogNo.17331-1)featuringconvenient,
quickplug-inchangefromhigh tolow impedancemicrophoneinput is
available foruse withthismodel. The machine canbe operated inthe
horizontal or verticalposition. Itis packaged ina durable,luggage-type,
saddle-tanSamsonitecase, oris obtainableuncased for custominstal-
lation.
TABLE 1-1
EQUIPMENTSUPPLIED
TAPESPEED TRACK LINEFREQ AMPEX DIMENSIONS
UNIT (ips) WIDTH (CPS) CAT. NO. (Ins.)
Complete
Equipment
(incarrying 7-1/2 Half 60 7948-1 16-1/2x13-3/4x8.
Case) 7-1/2 Full 60 7948-2 16-1/2x13-3/4x8.
7-1/2 Half 50 7948-5 16-1/2x13-3/4x8.
7-1/2 Full 50 7948-6 16-1/2x13-3/4x8.
3-3/4 Half 60 7948-101 16-1/2x13-3/4x8.
3-3/4 Full 60 7948-102 16-1/2x13-3/4x8.
3-3/4 Half 50 7948-105 16-1/2x13-3/4x8.
3-3/4 Full 50 7958-106 16-1/2x13-3/4x8.
TapeTransport 7-1/2 Half 60 6200-14 9-5/16x12-1/2x5.
7-1/2 Full 60 6200-10 9-5/16x12-1/2x5.
7-1/2 Half 50 6200-15 9-5/16x12-1/2x5.
7-1/2 Full 50 6200-11 9-5/16x12-1/2x5.
3-3/4 Half 60 6200-121 9-5/16x12-1/2x5.
3-3/4 Full 60 6200-122 9-5/16x12-1/2x5.
3-3/4 Half 50 6200-123 9-5/16x12-1/2x5.
3-3/4 Full 50 6200-124 9-5/16x12-1/2x5.
Electronic 7-1/2 17416-1 6-1/8x12-1/2x5.
Assembly 3-3/4 17416-101 6-1/8x12-1/2x5.
PowerCord CS-5
96.
MatingConnector,MicrophoneInput PL-33P
MiniaturePhonePlug,LineInput PL-450
MatingPlug,Output PL-445
Notes:
1. All matingconnectorsaresuppliedwithoutwiring asa convenience
fordiversifiedinstallation.
2. Hardwarekits are available to facilitatemaintenance. (See Sec-
tion VI.)

SPECIFICATIONS
Tape Width
Reel Size
Tape Speed
Playing Time
Reproduce Timing
Accuracy
Flutter and Wow
Starting Time
Stopping Time
Fast Forward Time
Rewind Time
Frequency Response
Signal-to-Noise Ratio
Record Inputs
Reproduce Output
Operating Controls
VA inch.
7inch,RETMAreel(maximum).
IV2 ips, lull track.
IVj ips,halftrack.
3Mips, full track.
.3Mips,halftrack.
Full Track—32 minutes witii 7 inchreel,
IV2 ips,1200 feet.
Half Track—64 minutes with 7 inchreel,
71/2ips,1200 feet.
±0.2%,oran accuracy of±3.6 seconds in
a30-rninuterecording.
71/2ips—Below0.17%rms.
ips—Below0.3%rms.
The tape attains full speed in less thanone-
fifth second ineithertheplayorrecordmode.
Less thanone second.
90 seconds for full 1200footreel.
90 seconds for full 1200footreel.
71/2 ips—40 to 15,000 cps±2db50to
10,000 cps down nomorethan4 dbat 15,000
cps.
3M ips—±2db50to 7500 cps.
Full Track—over55dbbelow peak rec-
ord level. Peak recordlevelisdefinedasthe
point of3%totalrmsiiarmonicdistortion,
measuredwhileusinga 400cpstone;and
peak recordlevelincludes bias, erase andre-
produceamplifiernoise.
Half Track—50 dbbelow peak recordlevel.
MICROPHONE:Accommodatesanyhigh
impedancemicrophone,andcanbequickly
convertedfora lowimpedancemicrophone
with the plug-in accessory transformer(Cat-
alogNo. 17331-1).
LINE: 0.5 volt requiredfornormalprogram
level.
1.23voltsrmsinto600ohmsatprogramlevel.
PLAY—REC:Theplaymodeis selected by
placing theswitchinPLAYposition.
Therecordmodecanbe selected onlybyde-
pressingthe safety buttonatthe same time
the selector switchisplacedinRECposition.
The safety button,a flattoppedneonlamp,
remainslightedwhilethemachineisinthe
recordmode.
REWIND—FASTFWD:This selector
switch ismechanicallyinterlocked with the
PLAY—RECswitch.
1-2
Reproduce Output
Operating Controls
Miscellaneous
Monitoring
Head Assembly
Power Requirements
Accessories
MIC RECLEVEL,andLINERECLEVEL
are separate mixingcontrols.
TheMONITOR SELECTOR switchisused
for monitoringasdescribedinthe following
paragraphs;butitfunctions also asanoper-
ating control.InthePLAYmode,the MON-
ITOR selector switchmustbeintheTAPE
position inordertobringthereproducehead
signaltotheOUTPUT.
A toggleON—OFFswitch,locatedonthe
control panel,turnspoweronoroff.When
placedintheONposition,thistoggleswitch
will cause the capstan torotate;butthe tape
will notmove until oneofthetwooperating
switchesisturned from itsneutralposition.
TheMICROPHONE input, a threecircuit
connector,isconvenientlylocatedonthecon-
trol panel.
ThePHONESoutputisa twocircuit jack,
locatedonthefrontpanel.
TheLINEINPUT connector isa twocircuit
jack recessed intothe right sideoftheequip-
ment.
TheOUTPUT connector isa threecircuit
jack also recessed intothe right sideofthe
equipment.
Mating connectors aresupplied(see Table
1-1).
TheMONITOR SELECTOR switchallows
monitoring ofprogram input, orreproduce
output. A phone jack andilluminatedv-u
meterareonthefrontpanel.
WhentheTAPEpositionis selected, there-
produceoutputcanbemonitored.
WhentheINPUTpositionis selected, the
headphones andmeterreportprogramsignal
level.
Separate erase, record,andreproduce heads
arecontainedina singlehousing.
117volts,50or60cps;0.52ampere,61
watts.
MaintenanceKit: 6392-1
Speed ConversionKitsto:
3M ips,60cps 7556-0
71/2ips,60cps 7556-1
3%ips,50cps 7556-2
71/2ips,50cps 7556-3
SPECIFICATIONS
1-3

SPECIFICATIONS Accessories
ConversionKitto:
50cpsoperation,714ips9738
60cpsoperation,71/2ips9739
50cp"soperation,354ips9740
60cpsoperation,354ips9741
Adaptor forrackmounting9684-1
Spare parrs kitsfor:
714ips,60cpsmachine9742-1
7V2 ips,50cpsmachine9742-2
354ips,60cpsmachine9742-3
354ips,50cpsmachine9742-4
Minor hardware Kits: 7802
SeeSectionVIfora complete parts list.
II.PrinciplesofOperation
If a material capable ofbeingmagnetizedisplacedinthe proximity Magnetic Tape
of a magnetic field, themoleculesofthematerial will beoriented
accordingtothedirectionofthe field. Anyofseveralmethodscanbe
used toproducethemagnetic field, butofmostinterestinmagnetic
recordingisthat field producedwhena current flows througha coil of
wire. Thecurrentmaybederived from a transducer—forexample,a
microphoneconvertingaudiosoundwavestoelectriccurrent.
Magneticrecording tape consists of finely divided iron-oxide par-
ticlesdepositedupona plasticbacking.This tape ismovedthrougha
magnetic field in which themagnetizingforceisalternating,andthe
iron oxideparticlesarealignedaccordingtothe instantaneous direction
andmagnitudeofthe field (SeeFig.2-1).
Fig. 2-1. Tape Magnetization
2-1

Magnetic HeadThemagnetic field isproducedinthegapofa recordinghead,
over which therecording tape passes. Therecordingheadisa ring-
shaped electromagnet(SeeFig.2-2).It consists ofanincomplete ring
of highly permeablematerialinsertedina coil of wire. Thediscontin-
uity inthe ring formsthegap,andthe ring isthecoreoftheelectro-
magnet.
GAP
TAPE
e
Fig. 2-2.Recording Head
Magnetization CurveThemagnetizationcurveofthe iron oxide utilized astherecording
medium issimilartothatshownastheheavy line inFig.2-3.Atpoints
nearthe origin, thecurveisextremelynon-linear,andthesignalrecord-
edonthe tape would notbe directly proportionaltothesignalapplied
to thehead.This would resultina high degree of distortion uponre-
production. This distortion isgreatlyreducedbytheapplicationofa
high-frequency constantamplitude bias signal which ismixed with the
signalbeingrecorded.Thefrequencyofthis bias isgenerally selected
to befivetimestheupperfrequency limit oftherecordertoprevent
beatingbetweenthe bias andharmonicsoftherecordedsignal.
Bias While the tape isintherecordinggap,the bias causes themagnet-
ization characteristicsofthe iron oxideto follow the dashed line loops
shown inFig.2-3, known asthe MINOR HYSTERESIS LOOPS.As
the tape leaves thegap,theinfluenceofthemagnetic field createdby
the bias isreducedtozero,andthe tape assumes a permanentmagnet-
ization, known asREMANENT INDUCTION, determinedbythegap
flux atthetimethe tape leaves thegap.
After therecording process, there exists onthe tape a flux pattern
which isproportionalinmagnitudeand direction tothesignalrecorded
on it.Ifthe tape isthenmoved past thegapofa reproducehead—
which issimilarinconstructiontotherecordhead—themagnetic flux
of themoving tape will inducea voltageinthe coil ofthereproduce
2-2
Fig. 2-3.Magnetization Curve
head.ThisinducedvoltageisproportionaltothenumberofturnsofInducedVoltage
wire onthehead,andtherateof change of flux, expressed inthefol-inHead
lowing equation:
E= N(d0at)
WhereE isthe induced voltage
N isthe number of turns ofwire
d0tlt isthe rate of change of flux
It isdesirablethatthegapinthereproduceheadbeassmallas
possible, sothatthegap will intercept less thanonewavelengthof
the signalonthe tape atthehighestfrequencytobereproduced. How-
ever,asthegapis made smallertheinducedvoltage decreases, sothere
isa practical limit in decreasing thegapand still maintainingan ade-
quate signal-to-noise ratio.

InducedVoltage
inHead
Thevoltageinduced across rheheadiscomputedbythe following
equation;
E= B V sin TTcj/
m /x
WhereE istheinduced voltage
B isthemaximumfluxdensityoftherecording
material
V isthevelocityofthe tape over thehead
w isthegapwidth
Xisthewavelengthofthesignalonthe tape.
From thisexpressionitcanbe seen thatthevoltage across thecoil
increases directlyasthevelocity increases andasthewave-lengthde-
creases (frequency increases). Ifrhetapevelocityandgap width are
assumedtobeconstant,the output voltage from theheadisdirectly pro-
portional tothefrequency,aslongasthewavelengthonthetapeis
largecomparedtothegap width. Thisresultsinan output vs.frequency
characteristicsuchasshownincurveA ofFig.2-4.Thevoltage does
not continuetorise indefinitely. Aselectrical losses inthe core mate-
rial increase, andasthewave-lengthonthetapeapproachesthe same
dimensionsasthereproduceheadgap,rheactual output resembles curve
BofFig.2-4.
OUTPUT
(db)
+25
+20
+15
+10
+5
0
-5
-10
-15
-20
-25
1
1
(
J^__.
1
1 A!/
1
1
1- +
1
t
1B
t
1B
——
10 100 1000
FREQUENCY
lOKC
Vig. 2-4.Output vs. Frequency
2-4
In ordertoprovideanoverallfrequency response thatis flat (see FrequencyResponse
Fig. 2-5)anequalizationcircuitconsistingofa series resistance and
capacitance isinsertedinoneoftheearly stages ofthereproduce ampli-
fier. Thisequalizerhasa high-frequencydroopcharacteristic(curveB,
Fig. 2-5) which istheinverseofthereproduceheadcharacteristic
(curveA,Fig.2-5).Inordertoextendthehigh-frequency response,
additional equalizationisincludedintherecordamplifierinthe form
ofa high-frequencyboostcircuit,designedtocompensateforthedroop
in reproduceheadcharacteristics caused byhead core losses, gap losses
and recording losses.
Fig. 2-5.Achieving Flat Response
2-5

III. InstallationandOperation
Thismachine canbe operated in either the horizontal or vertical
position. Inthe carrying case, installation consists only of making up
and connecting the required cables (See "Connector" in thissection).
Forstudioinstallations, an adaptor(Catalog No.9684-1)is available
which permitsmounting ina standard19-inchrelayrack.
GENERAL
Thepowerrequirements are117 volt a-c,50or60cps,0.52 ampere,
61watts. A nameplate onthe bottom ofthecase adjacent tothe aper-
ture for OUTPUT, LINE INPUT and117v.a-c indicates the proper
line frequency.
POWER
Theline input isan unbalanced bridging input of100,000 ohms.
Any unit connected tothe LINE INPUTconnectorshoulddeliver a sig-
nal ofat least 0.5 volt whenrecording from consolettes,mixers or other
taperecorders.
LINEINPUT
Therecorder is wired fora high impedancemicrophone, but pro-
vision for internalmounting ofan accessory plug-in transformerimme-
diately changes the machine foruse with low impedancemicrophones.
Tomakethisconversion,remove the four screws onthe panel ofthe
electronicsassembly. The panel and assembly can then be removed.
A. High Impedance--adummy plug J107P shown onthe sche-
maticdiagram(Fig. 5..5) must be plugged
into socket J106S for high impedance op-
eration.
B. Low Impedance — remove the dummy plug J107P. Acces-
sorytransformerAMPEXcatalognumber
173.51-1 (shown asT103on schematic dia-
gram Fig.5.3)is thenplugged into J106S
for impedance inthe range of150 ohms
to 250 ohms.
C. 30ohmto50 ohm — Installtransformer T103as shown on
the schematic diagram (Fig.5.3)by plug-
ging the transformer into socket J106, and
removing the jumper as shown in Note 7
on the schematic.
MICROPHONE
INPUT
Theoutput ofthe machineshould be connected toa unit having 600
ohms input impedance. Ina situationwherein the recorder will work
into a high impedance line, physicallyterminate the OUTPUT connec-
torwith a 600ohm resistor and bridgethisresistor with the high im-
pedance circuit. A threecircuitOUTPUT plug is supplied. A twocircuit
plug canbe used, and will work; butit automatically makes an unbal-
anced line. Ifan AMPEXamplifierloudspeaker is used plug it into the
MONITOR jackonly.
REPRODUCE
OUTPUT

INTERCONNECTING
Regardless ofapplication observe therequirementsunder"Line Input"
and"ReproduceOutput"wheninterconnectingthemachine with any
other piece ofequipment.
CONNECTORS A power cable andmatchingplugsfortheMICROPHONE (JIOIS),
LINE INPUT (J102S), andOUTPUT (J104S) connectors aresup-
plied with theequipment.
Shielded,low-capacity cable isrecommendedformakingup input
andoutput cables. Makesuch cables asshortaspossibleforintercon-
nectingunitsinaudio systems. Refer tothe schematic diagram(Fig.
5.3),todeterminecorrectpinconnectionforallplugs.
STUDIO Thereproducehead cable isdoubleshielded,insuringagainstr-f
INSTALLATION pickup. Cable capacityandlength have been minimizedtoavoidhigh
frequency loss. Ingeneral,mounttheelectronic assembly and tape trans-
port nomorethanonefootapart.Ifthereproducehead cable islength-
ened for greater separationofthecomponents,highfrequency response
will beaffected.Intheeventaninstallationabsolutelydemandslength-
eningthis cable, a verylowcapacitytype (RG-62/U) isindicated,plus
theadditionofanoutershield. High frequency losses cannotbekept
•'toa minimum ifthe cable length exceeds three feet.
Space requirementsforcustominstallationaregiveninthe accom-
panying illustration(Fig.3-1). Allow sufficient clearance atthe right
sideofthe electronics chassis for easy access toLINEINPUTandOUT-
PUT connectors. Ifdesired, these connectors canbebroughttoa patch
panelmountedat some moreconvenientpointintheinstallationtopro-
vide readyaccessibility.
Fig. 3-1. Space Requirements
3-2
The tape threadingpathdescribedbelowisthe same forall modes TAPE THREADING
ofoperation;butspecialattentioniscalledtothe notes dealing with
halftrack heads.
Step 1: Place a reelof tape ontheleft-handturntable,andanempty
reelontheright-handturntable,makingcertainthatthepins
around the base of each spindle engage corresponding slots on
thereelhubs.
Step 2: Press a reelhold-downknobin place on each spindle.
Step 3: Threadthe tape asindicatedinthefrontispiece.Make sure ,
theoxideor dull surface isagainstthe heads.
Step 4:Anchorthe tape intheslotontheemptyreelhubifdesired,
but a full tape turn counterclockwisearoundthereelhubis
usuallysufficient.
REEL
SUPPLY HOLD-DOWN TAKEUP
MICROPHONL MnNllLP LINE MICROPHONE
RECORD SELECTOR RECORD INPUT
LEVELLEVEL
Fig. 3-2. Tape Threading and Nomenclature
NOTE
Because machines usinghalftrack heads
recordorreproduceonlyhalfthe tape width,
the tape supplymustbesoorientedthatthe
halftoberecordedisfarthest from the tape
transport surface. Aftertheentire tape has
been woundontothetake-upreel from a re-
cording run,for instance, thetake-upreel
mustbeturnedoverandthe second halfre-
corded—orindentifiedfora laterrun.For
example:

RECORDINGStep 1: Threada tapeasdirectedunder"TapeThreading."
HALFTRACKStep 2: Setthemachineasindicatedin"Recording,"immediately fol-
lowing.
Step 3: Theentiretapemustbereeledontothetake-upreel,regardless
of whetherornottherecordingiscompleted.FAST—FWD
canbeusedifprogrammaterial does notusetheentiretape.
Step 4: Removethetake-upreel from themachineand turn itover.
Step 5: Removetheturntablereel which isnowfreeoftape.
Step 6: Place thetake-upreelontheturntableside.
Reversingthetake-upreelaftera recordingrun, places thetapeinthe
only positionforproperthreading from theturntableside;andalso
orients the still unrecordedhalfofthetapesothatitisfarthest from the
tapetransport.Ifthetapehadbeen rewound, thesecondrun would
have erased thepreviousrecording.
REPRODUCING Refer tothe steps in"Reproduce," following. Thehalftracktape will
UAic TDArir reproducecorrectly only iforientedsothatthehalfofthetapedesired
HALF TRACK• r i r i c
IS farthest from thetapetransportsurface.
In reproducemode,aftertheentiretapehasbeenreeledontothetake-up
reel, reversethereelandplaceitontheturntableside.
RECORDINGPreviouslyrecorded tapes are erased automaticallyasnewrecordings
aremade, eliminating theneedforanerasurerun because the tapes
first pass overthe erase headwheneverthemachineisrecording;but
for thefinest recording,itisrecommendedthatthe tapes betankerased.
Step 1: Connecttheprogramsourceequipment(microphone,mixers,
etc.)totheappropriate input.
Step 2: Place theMONITOR SELECTOR switchontheINPUT
function.
Step 3: Place theON-OFFtoggleintheONposition.
Step 4: Adjust eithertheMICRECLEVELorthe LINE RECLEVEL
control, dependingonwhethertheMICROPHONE input or
the LINE INPUTisbeingused,sothatonthemostintense
volume peaksoftheprogramtoberecorded,thev-umeter
needleswingstoapproximatelyzeroonthev-u scale. Itis
unnecessarytostartthetape motion inordertosetthe pro-
gram level.If only one input isbeingused, turn theother
RECLEVELtozero.
Step 5: Place thePLAY-RECcontrolintheRECpositionbydepress-
ing thesafety button atthe same timetherecordpositionis
selected.Thetransparentplastic button glows while thema-
chineisintherecordmode.Thisrecordsafetyfeatureprevents
accidentalerasureofpreviouslyrecordedtapes.When return-
ing tothePLAYortheneutralpositionatthedot,thesafety
button isnotused.
While recording,a continuouscomparisonoftheincomingprogram
and thereproductiononthetapecanbeeffectedby turning the MONI-
TOR SELECTOR switchbackand forth betweentheINPUTand
TAPEpositionsandobservingthev-umeter,orusingheadphones.
3-4
Tostoprecording, return thePLAY—RECcontroltoneutral,marked
by a dot.
RECORDING
Step 1: Threada previouslyrecordedtapeonthemachine.REPRODUCING
Step 2: Place theON—OFFtoggleintheONposition.
Step 3: Place thePLAY—RECcontrolinthePLAYposition.
Step 4: Place theMONITOR SELECTOR switchintheTAPEposi-
tion.
Step 5: Adjust thereproducelevel through thevolumecontrolofthe
program source.
If thereisno output, check theMONITOR SELECTOR
switch position.Whenthemachineisintheplaymode,
theMONITOR SELECTOR switchmustbeintheTAPE
position. OUTPUTcanbemonitored with theheadphones
plugged into thejackonthe front panel.
To rewind ormovetape forward rapidly, placeREWIND— FAST
FWD switchinthepositiondesired.Thetapemovesat800feetper
minute ineitherdirection,andcanbeshuttledbackand forth between
REWIND andFASTFWDpositions without waiting forthetapeto
decelerateorstop.Thus,cueingand editing canbeaccomplishedat
high speed with nodangeroftapebreakage.
TheREWIND—FASTFWDandPLAY-RECcontrolsaremechani-
cally interlocked,makingimpossibletheswitchingofeithercontrol
unlesstheotherisinneutral.Thissafetyfeatureguardsagainsttape
breakage which would occurifthemachinewereswitcheddirectly from
eitherofthe high speedmodestoPLAYorRECposition.
CAUTION
Always return REWIND—FASTEWDcontroltoneutral
position, and wait til tape motion stops beforeswitchingto
PLAY orREC.PlacingselectorcontrolsonPLAYorREC
while tapeisin motion will cause stretchedorbrokentape.
REWINDAND
FASTFORWARD
To erase a previouslyrecordedtapewhennonewreproductionisde-
sired, turn bothoftheRECLEVELcontrolstozeroandrunthetape
in therecordmode.
Because microphoneandlinerecordingchannelsareindependent, each
governed byitsownlevelcontrol,simultaneousrecording from two
sources canbemade without anexternalmixer.
Forexample,singing,voiceannouncementsorinstrumentalaccom-
paniment canbedubbed into a programbeingrecorded from a con-
soletteorothertaperecorder.Toeffect this, connecttheprogramsource
equipment tothe LINE INPUTconnectoranda microphonetothe
MICROPHONE connector. Adjust boththeMICROPHONEREC
LEVEL and LINE RECLEVELcontrolsfordesiredbalancebetween
thetwoprograms.
ERASE
MIXING
3-5

SYNTHETIC Special effects,similar to those obtainedthrough theuseofan echo
REVERBERATION
chamber canbe createdeasily.
Connect a microphoneand set theprogramlevel as usual;thenconnect
the OUTPUTconnector tothe LINEINPUTconnector, turn the
MONITOR SELECTOR switch to TAPE,andstartrecording.The re-
verberation decay rate, which is thetimerequired forthe echo todie
away, canbe varied with theLINE REC LEVEL control. The Control
valuechosen will depend entirely on theeffectdesired. If the control is
settoo high, continuousoscillation will result,andthev-umeterneedle
will swing to maximumandremainthere. If this happens, adjust toa
lower setting.
3-6
IV. Tape Transport Assembly
The tape transportmechanismincorporates a single-speed synchronous GENERAL
motor and a system of pulleys,belts,andclutches to drivethe capstan
and the turntables.Three modes of tape motion (PLAY, REWIND,
and EAST FORWARD) are determined by twocontrolslocated on
the toppanel of the tape transport.(Theneutralpositionfor each con-
trol is marked bya dot.)
Thebracketednumbersinthissectionrefer to partsshown in Fig.4-1,
Fig. 4-4,andin theparts list attheendof thismanual. For greatest
facility in following thediscussionbelow, itis suggested thatFig. 4-4
beopened fully for readyreference.
Power is applied to thedrivemotor (63) whenthePOWERswitch onSTANDBY
the front panel of theelectronic assembly is turned to theONposition. OPERATIC
The capstan (42) begins to rotateimmediately,being driven bya
nylon belt (68) which runsbetween the motorpulley (61)andthe
capstan flywheel. A second belt (69) running ina groove in the cap-
stan flywheel drives the playtakeuppulley (40).The shock relief
brakerollers (2)are engaged against therubber-tired fast forward and
rewind clutches (16and 31).Bothturntables are motionless, andthe
machine is instandby condition.
Since the capstan is in motion whenthemachine is inthestandbycon-
dition, the tape will accelerate to full play speed almostinstantlywhen
the PLAYswitch is operated,thusproducing a wow-freestart.
When the PLAY control is energized the following mechanical se-PLAYMODE
quence occurs:
1)Theplaytakeuppulley (40) andbelt (69)are brought to bear on
the playtakeup clutch (19).
2) The shock relief brake roller (2)onthe playtakeup side isre-
leased from the fast forward clutch tire (16).
3) The capstan idler (79) engages the capstan (42), which drives
the tape, pulling it from the tape supplyturntable(i.e.the rewind
turntable) and feeding ittothe takeupturntable, which now be-
gins to rotate. Itis especiallyimportant to understandthatwhen
the machine is operatingnormallyintheplaymode, in which the
tape is clamped against the capstan by the capstan idler, the turn-
tables are effectivelyisolated from each other. The takeup turn-
table, as its name implies, does nothing morethantake up the tape
fed toitbythe capstan. It does not pull the tape from the tape
supplyturntable.
4)Theshock relief brake roller (2)on the rewind side remains en-
gaged against the rewind clutch tire (31),and slippage occurs
betweenthe clutch and disc assembly (30).The friction produced
in this slippage, andthe friction produced by the rewind holdback
brake (37) operating onthe bakelite drum (35) providethe re-
quired holdbacktension.
4-1

©
SHOCK RELIEF BRAKE
©
HOLDBACKBRAKE
0
REWINDIDLER,
©
PLAY TAKEUPPULLEY
©
FAST FORWARDCLUTCH
©
CAPSTANFLYWHEEL
©
PLAY TAKEUPCLUTCH
©
MOTOR PULLEY
@
HOLDBACKBRAKE NYLONDRIVEBELT
©
REWINDCLUTCH
©
TAKEUPBELT
®
HOLDBACKBRAKEDRUM
©
CAPSTANIDLER
Fig. 4-1. Mechanical Operation Simplified
4-2
The REWIND-FAST FORWARD control cannotbeoperated unless
the PLAY control isinneutral.Whenthe REWIND-FAST FOR-
WARD control isturnedto REWIND:
1)
2)
3)
Both shock relief brakerollers(2) arereleased.
The rewind idler (7)isclampedbetweenthemotor pulley (61)
andthe rewind clutch tire (31)andthe rewind turntableis
driven.
Holdback tensionisprovidedbytheholdbackbrake(25)onthe
takeupassemblyas tape is pulled from thetakeupturntable.
REWINDMODE
When the REWIND-FAST FORWARD control isturnedto FAST-
FORWARD:
1) Both shock relief brakerollers( 2 ) arereleased.
2) Therubber-tiredfast forward clutch (I6)isbroughtto bear on
themotor pulley (61)anddrivesthetakeupturntable.
3) Holdbacktensionisproducedbytheholdbackbrake(37)onthe
rewind assembly.
FAST FORWARD
MODE
OBIVEMOTOR(0 PPER REARING)
Vig. 4-2. Routine Lubrication

Routinemaintenanceofthe tape transportmechanism consists pri-
marily ofperiodiccleaningandlubrication.
Cleanliness ofallpartsofthe tape drivemechanismisrequiredforcon-
sistentoptimumperformance.Most tape manufacturerslubricatetheir
tapes; thislubricant will gradually form a coatingonthehead assembly
andtheidlerwheelsandmay cause loss ofpositivedriveatthe capstan.
Therefore,periodiccleaningofboththehead assembly andallpartsof
the tape drivemechanismisparticularlyimportant.Therecommended
agent forcleaningAmpexHead Assemblies isa mixtureofXyleneand
0.1%Aerosol.This agent isavailablein2 02.bottles.(AmpexCatalog
No. FP-7.) Tocleananyhead assembly simply wind a clean,lintless
cloth ona swab-stickandmoisten with thismixture. Swab the heads
periodically toremoveall dirt andoxidewhichmay have accumulated
from thetape.Cleanallparts except thehead assembly with a clean,
lintlessclothmoistened with denaturedalcohol.
CAUTION
Donotuseanyothersolventsasthereare some whichmay damage the
adhesive usedtoholdtheheadlaminationstogether.
Therecommendedstandardlubricantforthefour places whichre-
quire periodiclubrication(motorand capstan) isCaloilNo.OC-11.
Thislubricantisavailable from AMPEXas Stock No. 70-9 (V2oz.
oiler)orFP-5 (402.)
NOTE
Theproperlubricantisavailable from AMPEXas Stock No. 70-9
(1/2 oz.oiler)orPP-5 (4oz.).
Theupperandlowerbearingsofthedrivemotorshouldbelubricated
afterevery500hoursofoperation.Theupperoilholeofthemotoris
accessible througha holeinthe tape transportgrilleslightly above and
to theleftofthetakeupturntable.For access totheloweroilhole,lo-
cated inthesideofthemotorendbell,removethe tape transport from
the case (SeeFig.4-2).
Fourorfivedropsofoneoftherecommendedlubricantsissufficient.
Care shouldbetakentoavoidover-oilingorspills.Anysuch excess
should bewipedaway with solvent.
The capstan mayrequire oiling about once foreveryfouroilingsofthe
drive motor.For access totheupperbearing,the capstan idlermust
first beremoved(SeeFig.4-2). Remove therubbercapontheidler.
Remove thehairpinretainerand lift theidleroffitsshaft,taking care
notto lose the washers associated with it.Thealuminumplug-bottom
overthe capstan shaftmaynowbepriedoffandthefeltwasherbeneath
it removedto expose theupper capstan bearing.Useasmuchofone
oftherecommendedlubricantsasthebearing will accept, wipeaway
any excess, and reassemble.
CAU7I0N
Donotoilthefeltwasherwhich serves onlyasa dustprotectorand
to keep oil from working itswayupthe capstan.
For access tothelowerbearing,removethe tape transport from the case.
4-4
ROUTINE
MAINTENANCE
Cleaning
Lubrication
TheoilholeislocatedinthebearinghousingasshowninFig.4-2.
Use exactly four drops of oil—no more.
Donotoilanyotherpartsofthe tape transportmechanism.Allother
bearingsandmovingpartsarelubricatedfor life.
It maybesaidingeneral,thatmostofthedifficultiesthat will normally
beencounteredintheModel601 tape transportmechanism will be
traceable tocontaminationofbelts,pulleys,bearings,andother friction
surfaces, whetherdueto carelessness inroutinelubrication,ortothe
gradual accumulationof dirt andotherforeignmaterialtobe expected
overa reasonable lengthoftime.Correctionof these difficulties will
usuallybea matterofcarefuldisas.semblyandcleaning,ratherthanre-
adjustmentofthemechanism.Thenormaltorques(and hence, tape
tension)inthismechanismare,infact,fixed within strictdesignspeci-
fications, andarenotadjustable.Themeasurementof these torques will
frequentlyprovidea rapid means forisolatingthe source ofmechanical
troubles.
Mechanical
Troubleshooting
Z"W—SEE NOTE
II
HOLDBACK
53/4-B 3/4 OZ,-IN.
2-3 1/2 OZTIN,
5-7OZ.-IH.
HOLOaACK
V4-[1/4 OZ.-IPt.
3/4-1 1/4OZ-IN
TAKEUP
5-702.-IN.
FAST FOHWARD
NOTES:
1. IFREELHUBDIAMETERISLARGERORSMALLER THAN 2 INCHES, MUUTIPLY
SPRINGSCALEBEADINGBYHUBRADIUSTOOBTAIN OZ.—IN. READING ,
2. PULLSCALEWITHSTEADYMOTIONWHENMEASURINGHOLDBACKrENStONS.
ALLOWSCALETOMOVEINTOWARDREELWHENMEASURtNSTAKEOPTENSIONS.
TAKE ALLREADINGSWHILESCALEISINMOTION.
Fig. 4-3. Tape Tension Measurements
4-5

Torques andThemeasurementoftorquesonthe Model 601requiresthe following
TapeTension equipment:
1)A light-movement spring scale (e.g.Post-A-Let,0 to8 oz,,Exact
Weight Scale Co.,Columbus,Ohio.
2)A measuringhub.A standardRETMAplasticreelmaybeused.If
thehubdiameterisexactly2 inches,the spring scale will read
directly inounce-inches. Reels with smallerhubscanbebrought
up to2-inchdiameterby winding onsufficienttape.Ifa reelof
greaterthan2-inchhubdiameterisused, multiply the spring scale
reading bythehubradius toobtaintheounce-inchreading.
3)A pieceof string, approximately30inches long, with a smallloop
tied atoneend.
Torquesmeasuredonthe driven turntableinanymode,(i.e.the turn-
tableon which thetapeisbeingwound)area measureof takeup ten-
sion. Torquesmeasuredontheturntable from which thetapeis pulled
•inanymodearea measureofholdbacktension(SeeFig.4-3).
Takeup
Tension
Step 1:
Step 2:
Step 3:
Place themeasuringhubonthe driven turntable.
Wind a fewturnsof string aroundthehubinthedirectionof
normal tape wrap, andattaclithe spring scale totheloopat
theend.
Startthemachineintheappropriatemodeand,asthe string
,is wound onthehub, allow the scale tomovein with it,tak-
„ingthereading while the scale isin motion. Normal torques
areas follows:
Fast Forward5 to7 oz-in.
Rewind 5 to7 oz-in.
Play2 to3V2 oz-in.
HoldbackTension Step 1:
Place themeasuringhubontheturntable from which thetape
is pulled inthemodeinoperation.
Step 2: Wind the string on fully inthedirectionofnormaltape wrap,
and attachthe spring scale.
Step 3: Startthemachineintheoppropriatemode,and pull the scale
slowly inthedirectionin which tapeisnormally pulled from
this reel, taking thereading while the scale isinsteadymo-
tion. Normal torquesareas follows:
Fast Forward->4toU/i oz-in.
Rewind % to1(4 oz-in.
Play5%to8 4 oz-in.
These valueslistedaboveforbothtakeupandholdbacktensionsmay
be close tothelower limit whenthemachineisnew,and will usually
move up toward tlie upper limit afterthe first 10or12hoursofopera-
tion.
Malfunctions
inPlayMode
Nearly allmalfunctionsintheplaymode will bereflectedas flutter and
wow in excess ofspecifications.A quickcheckoftakeupandholdback
tensions,discus.sedintheprevioussection,mayleaddirectlytothe
sourceoftrouble.Possible causes of flutter andwowaresuggestedin
the following check list.
4-6
The word "contaminated,"asusedhere,mayindicateeitherthepres-
ence ofoilwhereitisnotwanted,oraccumulationsof dirt andother
foreign matteronpulleysandbelt.Ineither case, carbontetrachloride
isrecommendedasthecleaningagent. After cleaninga contaminated
part, cleananyotherpart with which itnormally comes into contact
whether ornotthatpartshowsanyimmediateevidenceofcontamina-
tion. Bracketednumbersrefertopartsshownintheexploded view of
themechanicalassembly.Fig.4-4, which shouldserveasa guidefor
any necessary disa.ssemblyandreassembly.
Rewind andfast forward malfunctions will usuallybereflectedasan
apparent loss ofpowerinthosemodes,loosetape wind, erratictapemo-
tion orslippage,and,possiblyno rewind orfast forward atall.The first
stepistomakea quickcheckof rewind orfast forward takeupand
holdback tensionsasdescribedpreviously.Themalfunctionsdiscussed
below applytoeithermode,theturntables,associatedcomponents,and
tapedirectionsbeingoppositeof each other.
Starting, stopping,and shuttling malfunctions will beevidencedbythe
throwing oftapeloopsand,inextreme cases, bytapebreakage. These
troubles areusuallyassociated with lowtakeuptensionofbrake mal-
functions produced primarily bytamperingormisassembly,orcontam-
ination dueto careless oiling oraccumulationof dirt.
Malfunctions
inPlayMode
Malfunctionsin
RewindorFast
ForwardMode
Starting, Stopping
andShuttling
Malfunctions
The following sectioncoverssomeadjustments,critical clearances, and Assembly and
alignment which mustbemaintainedinreassemblingpartsofthetape ConstructionNotes
transport mechanismthatmayhavebeendisassembledforservicing.
Two generalprecautionsshouldbeobservedinanyrequireddisassembly:
1) Always notethenumber,type,andlocationofwashersinanas-
semblyverycarefully.Shouldwashers,retainersorothersmall hard-
ware belostordamagedinservicing,a kitcontaininganassortment
of suchhardware(AmpexCatalogNo. 7802) isavailable through
your dealer.
2)Toremovethesub-plate(1),a preliminary toanyfurtherdisas-
semblyofpartsunderthetopplatecasting,remove only thethree
elasticstop-nutsthat hold it,andclevispinthat links theslidelever
(13)totheloweryokeoftherewind/fast forward actuator(48).
It isunnecessarytoremovetheadjustmentscrews(70and71)for
thecapstanthrustandthemotorthrust.Ifthesettingsof these
screwsarechanged,theymustbecarefullyreadjustedasdescribed
in the following subsections.Thethrustdiscs(65)beneath these
screws,beingcoated with grease, will usuallystayinplacewhen
thesub-plateisremoved.Itisadvisable,however,tobesurethat
they donot fall out.It will generallybe found easiest tore-install
thesub-plateafterservicing,ifthePLAYcontrolisenergized.
Thetapetransportincorporatesrubbershockmountsonthescrewsre-
taining themotor mounting platetothetopplatecasting. These shock
mounts provideautomaticcenteringofthedrivemotorandnoadjust-
mentsare necessary.
Thedrivemotorthrustisa hardenedsteel ball (60)againsta nylon DrivemotorThrust
4-7

DrivemotorThrust disc (65).The capstan thrustisadjustedbya set-screw (70).Endplay
of.010in.to.015in.isrequired,andisobtainedasfollows:
Step 1: Coat thenylonthrust disc liberally with wheelbearing grease
anddropitthroughthethreadedholeinthesub-plate(1)
overthe capstan shaft.
Step 2: Insertthe set-screw, andtightendown until itisfelttobot-
tom onthethrustdisc.
Step 3: Grasp the capstan flywheel(42)betweenthethumbandin-
dexfinger.
Step 4: Whilemaintaininga slightdownward pressure onthe head
ofthe set-screw with thescrewdriver(tosimulatethe pressure
that will laterbeappliedbythelocking screw) startbacking
the screw offslowly,andworkthe capstan flywheel upand
down until anaudibleclickatthe ends ofitstravelindicates
the presence ofendplay.This will usually occur whentheset-
screw has been backed offapproximately14ofa turn. Atthis
point, endplayshouldbeintherequiredrange.
Step 5: Tightenthelockingnutontheset screw, then recheck end
play.
TurntableHeightTurntableheight(the distance measured fromrhetop surface ofthe
turntable(78)totheperforatedmetalgrille)shouldbe.125in., ±.008
in. Thisheightisdeterminedbythe replacement oflamicoid washers
betwenthebottomoftheturntablepivot(24or36)andthehairpin
retainerontheshaftthroughthepivot.Difficultiesin tape tracking
tracedtoimproperturntableheightmaybecorrectedbyincreasingor
decreasing rhenumberor thickness of these washers.
PlayTakeupClutchTheplaytakeupclutch assembly consists ofa felt-linedaluminum disc
(18),anda bakeliteclutch(19)whichisspring-loadedtothedisc.
Whenthemachineisintheplaymode,theclutchisdrivenbytherub-
berbelt(69)ontheplaytakeuppulley(40).Locationofthefelt-lined
aluminum disc iscritical—a clearance of.015in.beingrequiredbe-
tweentheendoftheoilitebearing(21)which goes throughthe bake-
lite clutch(19),andthebottomofthealuminum disc (18).This clear-
ance, which cannot be measured directly with a gauge because ofthe
physicalarrangementcanbesetquite accurately bythefollowingin-
direamethod:
Step 1: Inserta removable.015in.shimor feeler gauge betweenthe
thrust washer thatridesontheinner race ofthelowerball
bearing(22)ofthetakeupturntablepivot(24)andoilite
bushing(21).
Step 2: Assemble theconicalspring(20),thebakeliteclutch(19),
andthefelt-linedaluminum disc (18)(inthatorder)onthe
turntableshaft(29).
Step 3: Guidetheendoftheoilitebushingthroughtheholeinthe
center ofthebakeliteclutch,and press thealuminum disc
down until itbottoms firmly ontheendofthebushing.
Step 4: Holdingthe disc platein place, tightentheset screw inits
hub.
Step 5: Remove theshimor gauge. Theexpansionoftheconical
spring will then force theoilitebushing back oflfthealumi-
num disc,thuscreatingtherequired.015in. clearance.
4-8
Therubber-tiredbakeliterewind(31)and fast forward clutches must
line up with the shock reliefbrakerollers( 5)sothattherollers engage
the full width ofthetires.Inaddition,therewindclutch(31)should
bealignedfor full-width contact with therewindidler(7)andthe fast
forward clutch(16)for full width contact with themotorpulley(61).
Rewindand
FastForward
ClutchAlignment
The capstan speed will notvary, since the capstan isdrivenbya non-
slipping nylonbeltandsynchronousmotor.Noadjustmentofthe cap-
stan speed will be necessary. Ifitisdesiredto check the capstan speed,
usea pre-recorded 5000 cycle tape,thathas been recordedona machine
ofknown accuracy, andan electronic frequencycounter.
CapstanSpeed
Trouble
EXCESSIVE OR ERRATIC
HOLDBACK TENSION
EXCESSIVE TAKEUP
TENSION
DRIVEMOTOR OUT
OE SYNCHRONISM
felt
tire
too
1.
2.
TABLE 4-1
Troubleshooting PLAY Model Malfunctions
Probable Cause
1. Contaminatedrewindclutch
(.30).
2.Contaminatedrewindclutch
(31).
3.Rewindclutchspring(32)
stiff. Thisactuallyindicatestam-
pering or carelessness in reasembly.
It isadvisableto replace thespring
ratherthantoattemptmakeshift
readjustment.
Contaminatedplaytakeupclutch
felt (18).
Oilite bearing(21)bottomingon
aluminum clutch disc (18). Mini-
mum clearance shouldbe .015".
Seesub-paragraph8.4belowfor
adjustmentprocedure.
3. Takeupclutchspring(20)too
stiff.
1. Linevoltagebelow105voltsa-c.
2. Excessive playtakeuptension.See
trouble above.
3. Nylon drivebelt(68)tensionex-
cessive. Seesub-paragraph8.1be-
low.
4. Belt tensioningidler(55)drag-
ging.
5.Drivemotorthrustmisadjusted.See
subparagraph8.2below.
6.Defectivedrivemotorstartingca-
pacitor.
7.Dry bearings indrivemotor(63),
capstan (42),or capstan idler(79).
Seelubricationinstructions.
8.Defectivedrivemotor(63).
4-9

FLATTED OR DENTED
CAPSTAN IDLER TIRE
DEFECTIVE OR IM-
PROPERLY INSTALLED
NYLON DRIVE BELT (68)
REWIND IDLER (7) NOT 1,
DISENGAGING FROM
MOTOR PULLEY (61)
REELS MISALIGNED WITH 1.
RESPECT TO TAPE GUIDES
If the capstan idler(79)is left en-
gaged overanextendedperiod
whenthemachineisnotoperating,
theidlertiremay become dented.
If runningthemachineintheplay
modefor several hours does notre-
storethetiretonormal,theidler
mustbe replaced.
Belt splicedimproperly.
Belt installed with splice joint
toward pulley.
Belt worn because misalignedmo-
tor pulley(61) causes thebeltto
track against oneofthe capstan
pulley flanges (42).
Contaminatedrewindidler guide
(8).
This will usually cause tape scrape
which mayormaynotbeaudible
but will generally appear asflutter.
See subparagraph 8.4below.
TABLE 4-2
Troubleshooting REWIND and FAST FORWARD Mode Malfunctions
Probable Cause
Clutch leafspring(17and32)too
weak, usually caused bytampering.Re-
place. Neverattemptto increase re-
wind takeuptensiontooffsetother
problems.
1. Contaminatedholdback wipes (25
or 37).
2.Bakelitedrum(23or35)onwhich
wipe operates has been roughened.
Evidenceofbentor misassembled parts.
Checkexplodedview,Fig.4-4.
Trouble
TAKEUP TENSION
LOW
EXCESSIVE HOLD-
BACK TENSION
BRAKE SHOCK RELIEF
ROLLER (2) NOT RE-
LEASING FROM FAST
FORWARD CLUTCH (16)
REWIND IDLER (7) NOT
ENGAGING MOTOR
PULLEY (61) BIND IN
REWIND IDLER BEARING
(PART OF 7)
MALFUNCTIONING
TURNTABLE PIVOTS
(24 or 36)
Bind inidler guide (8) caused bycon-
tamination.
Bind inturntablecenteringdetent
(77).
TABLE 4-3
Troubleshooting Starting, Stopping, and Shuttling Malfunctions
Trouble
TAPE LOOP THROWN
ON STARTING IN PLAY
MODE (LOW PLAY
TAKEUP TENSION)
TAPE LOOP THROWN
ON STOPPING OR
SHUTTLING
3.
Probable Cause
Play takeupbelt(69)contam-
inated.
Nylon drivebelt(68)contami-
nated.Ifeithertheplaytakeupbelt
or thenylondrivebeltiscontami-
nated with oil,anoveroiledmotor
or capstan isindicated.Cleanall
affected parts thoroughly with car-
bon tetrachloride.
Slippage betweenplaytakeupbelt
(69)andclutch(19)dueeither
to weak playtakeuparmspring
(41)or bind inplaytakeuppulley
bearing(partof40).
Bind inturntableshaft bearings
(22or24)duetocontamination.
Cleanandlubricate with twoor
threedropsofmediumweightoil.
Play takeup brake release (14)in-
operativedueto bind, weak orun-
attached spring(11) causing shock
relief roller(2)todragonfast
forward clutchtire(16).
One or both brake shockreliefac-
tuators(2)binding.
One or both brake shockrelief
springs (12)off.Endloopson
these springs mustbe fully closed
to preventtheirbecomingdiscon-
nected.
Bind inturntablecenteringdetent
(77).

V.Electronic Assembly
Theelectronic assembly consists ofa recordchannel,a reproducechan-
nel, a bias and erase oscillator,anda powersupply,mountedona single
chassis.
GENERAL
Therecordchannel consists ofa two-stagemicrophonepreamplifier RECORD CHANNEL
VlOl andV102Aanda three-stage amplifier, V102B, V103A, V103B
(Fig. 5.3).
When dummy plug J107P isinsertedin receptacle J106S inthemicro-
phonepreamplifier,themicrophone input matches a high impedance
microphone.A plug-in transformer,availableas accessory equipment,
will providethepropermatchfora lowimpedancemicrophone.
TheMICROPHONE input JIOIS andLINEINPUT J102S have sep-
arate controlsR106andR125respectively.Bothinputscanbeused
simultaneously. Mixing takes place inthe first stage oftherecordam-
plifier, V102B. Signals intherecordchannelarepickedoffthe REC-
ORDCALIBRATIONpotentiometerR114attheoutputofthis stage,
and canbeswitchedtotheoutputamplifierthroughtheMONITOR
SELECTOR switch SI02, formonitoring.
Recordequalization,accomplishedinthe grid circuitofV103A,and
thecathodecircuitof V103B, isadjustedbytrimmerC107. Plate volt-
ageissuppliedtothelast stage oftherecordamplifier, V103B only
when switchS201onthetapetransportisintheRECposition.
Thereproducechannel consists ofa two-stagereproduceamplifier, REPRODUCE CHANNE
V104,V105anda two-stageoutputamplifierV106Aand V106B.
Thesignal from thereproducehead appears atconnectorPIOIP.Re-
produceequalizationisprovidedbyCI16andR130.Levelisadjusted
by potentiometerR137.
Thereproducesignalisfedtotheoutputamplifierthroughthe MONI-
TOR SELECTOR switch when it is in tape position. Theoutput ampli-
fier consists ofonevoltageamplification stage V106A,anda cathode
follower output stage V106B, which istransformer-coupledtoOUT-
PUTconnector J104S. A v-umeterandresistorshuntthisconnector.
The bias and erase oscillatorisanLCpush-pulloscillatoroperatingat BIAS AND ERASE
approximately 100kc.TheNOISEBALANCEpotentiometerR147 OSCILLATOR
commontobothgridsoftheoscillatorisadjustedtoeliminateany
asymmetryinwave form. Lackofwavesymmetry would introducea
d-ccurrentintherecordhead,causingpermanentmagnetizationanda
resultantdistortedsignal. Bias levelisadjustedbytrimmerC113.The
oscillator,dependentonplatevoltage, operates onlywhenswitchS201
isintheRECposition.
5-1

BIAS AND ERASE Thed-cplatesupply consists of a full waverectifierV108,and a ca-
OSCILLATOR pacitor-inputL-C filter. A 6.3 volt secondary winding onthepower
transformerfurnishes a-c power to allheaters.PotentiometerR150
HUM BAL is adjustedfor minimum hum.
ELECTRONIC Alignment consists in makingall necessary adjustmentsforproper
ALIGNMENT electronicperformance. A recorderoutofalignmentmaybecharacter-
ized bypoorfrequency response, high noise,low output, high distortion,
or a combination of these faults.AllAmpexrecordersarecompletely
aligned at thefactory,and no adjustmentsshould be necessary. The
overall performance checks outlinedinSection 3 will generally serve
to determine if realignment is necessary at anytime.
Alignment can be accomplished without removingtheelectronic as-
sembly from the case. If desiredtheelectronicassemblycan be with-
drawn byremovingthefour screws onthe front panel.Standthe case
in a verticalpositionand pull theelectronicassembly forward. The
interconnecting cables betweentheelectronicassemblyandthetape
transport aresufficientlylongfor access to alladjustments while the
units areconnected.
ALIGNMENT AND
TEST EQUIPMENT
REQUIREMENTS
The following equipmentisrequiredforproperalignmentandtesting:
A. Audio Oscillator—Hewlett-Packard Model 200C orequivalent.
B. Vacuum Tube Voltmeter—Hewlett-Packard Model 400C or
equivalent.
C. Ampex Alignment Tape—Catalog No. 5563. Thistape is re-
corded atIV2 ips 10 dbbelownormaloperatinglevel as
defined inSection3.Thetapecontainsvoiceannouncements
ofthe following tone sequence: reproduceheadalignment
tone, reference toneforreproduceleveladjustment,tone
series forreproduce response check.
D. Ampex Head Demagnetizer—Catalog No.704.
E. High Impedance Headphones
F.Small Screwdriver
Head
Demagnetization
Demagnetizetherecordandreproduce heads beforealigningthema-
chine.The erase headrequiresnodemagnetization.Magnetized heads
will generallyproducean increase of5 to10dbinnoiselevel, distortion
oftherecordedsignal,and will gradually erase the high frequencieson
anytape passed overthem.
Demagnetization Step 1: Removeboththeheadcoverandthemumetalshieldoverthe
Procedure headassembly.
Step 2: Place theON—OFFswitchintheOFFposition.
Step 3: Coverthetipsofthedemagnetizer with scotchtapeormask-
ing tape.Thispreventsscratchingtheheads.Plugthedemag-
netizer into a source of 117-volta-cpower.
Step 4: Thehead sequence from leftto right whenfacingthemachine,
is erase head,recordhead,reproducehead.Bringthetips of
thedemagnetizer into contact with therecordhead stack. The
5-2
tips shouldstraddlethegapinthe center of the stack. Run Demagnetization
thetipsslowlyupand down the stack severaltimes,andthen Procedure
withdraw thedemagnetizer very slowly. Slow withdrawal is
required forthoroughdemagnetization.
Step 5: Repeat step 4 onthereproducehead. Itis not necessary to
demagnetizethe erase head.
Step 6: Replace theheadshield,butdonotreplacetheheadcover if
alignment will follow.
The following steps constitutethecompletealignmentofthereproduce
channel.
A. ReproduceHead Azimuth Adjustment
B.ReproduceLevelSetting
C.Reproduce Response Check
D. ReproduceEqualization
E.Hum Balance Adjustment
Reproduce
Channel
Alignment
Step 1: Threadthealignmenttapeonthemachine.Terminatethe
OUTPUTconnector with a 600 ohmresistorandconnect
the vtvm across thisload.Plug a set of high impedancehead
phones into thephonesjacksothatvoiceannouncementson
thetapecan be heard. If notalreadydone,removethehead
assemblycover,butnotthemumetalshieldbeneathit. Place
theMONITOR SELECTOR switch in TAPEposition,and
startthemachineinthereproducemode.Theheadalignment
tone will beannounced first.
Step 2: Insert a smallscrewdriverthroughthe access hole nearest the
right hand edge of theheadshield,andadjusttheazimuth
screwformaximum output observedonthe vtvm. //the head
is far out of alignment, several minor peaks occurring on
either side of a maximum may he observed. Makecertainthat
themaximumisclearly 15 to20dbgreaterthananyof these
minor peaks.
Reproduce Head
Azimuth Adjustment
Thenexttoneonthetape is forreproducelevelsetting.Adjustthe Reproduce
REPRODUCELEVEL(P.B.LEVEL)potentiometerR137for a vtvm LevelSetting
reading 10 dbbelownormaloperatinglevel, which is approximately
0.4voltsrms.
Thenext series of tones is forthereproduce response check. Observe
the response indicatedonthe vtvm, and check it againstspecifications.
If reproduce response failstomeetspecifications,thetroublemaybe a
worn orotherwise faulty reproducehead, a partially erased alignment
tape,duetoheadmagnetization, or improperequalization of there-
produceamplifier.Equalizationcanbecheckedandadjustedasindicated
below.
Reproduce
Response Check
5-3