Brenell Mark 5 Series 2 User manual

OPERATING INSTRUCTIONS
forthe
Brenell
Mark 5 Series 2
TAPE RECORDER
IMPORTANT
Before attempting to operate this
instrument, be sure to study careful
these instructions. In the event
of damage to the Recorder through
wrong connection or other misuse, the
manufacturers can accept no
responsibility.
Price: Five shillings

GENERAL DESCRIPTION includingrecording and playback
sequences, together with:
Hints for improving recordings ............ Page 8
Incorporating into a Hi-Fiinstallation ......... Page II
Maintenance Page 14
Specification Page 20
Glossary Page 22
Fig. I
Feed Spool
Spool Retaining Screws
Take-upSpool
Guide Pillar
Adjustable TapeGuide
Revolution Counter
Record PlaybackSwitch
Record Lock Button
Pause Control
Superimpose Control
RewindSwitch
Speed SelectorSwitch
Fixed HeadCover
Clip-on HeadCover
FUNCTION SWITCH—Record, Playback, Amplifier
FREQUENCY CORRECTION—IJ, 3|, 7f 15
RECORDING LEVEL INDICATOR—Magic eyeor meter
VOLUME CONTROL—Operative onall functions
TONE CONTROL—Bass boost(clockwisemaximum)
MOUNTING SCREWS—Fixing amplifier to cabinet
EXTENSION SPEAKER—Preferably IS ohms
MONITOR—For highimpedance headphones
INDICATOR LAMP—Straight amplifier
ZERO CONTROL—When meter is fitted
INDICATOR LAMP—Playback
RADIO/GRAM. INPUT—For high-levelsignals
MICROPHONE INPUT—For low-level signals

MAINS CABLE
This isa three-cored cable which is stored inthe left-handrear
compartment(viewed from the rear).
Choose a suitablethree-pin mains plug and connect the greenlead
tothe earth pin (largest) andthetwo remaining leads tothe smaller
pins. If a two-pin plugmust be used, the green(earth)leadmust be
leftdisconnected and suitablyinsulated.
MAINS ADJUSTMENT PLUG
This is situated within right-handrearcompartment and contains
the mains fuse which is easily renewed.
Ensure that the plug issettothe correctvoltageposition for your
electricitysupply.
i.e., 240V for mains of 220V to 250V
210 V for mains of200V to220V
*IIOVfor mains of 100 V to 125V
(thepowerconsumption is approx. 100 watts).
*Use ONLY onthe special model fitted with 117 V motors and suitable
ONLY for use on 100-125 V A.C. supplies. DO NOT operate the
special model on higher voltage mains supplies unless a suitable step-
down transformer is used.
A converter to enable the machine tobe operated from D.C.mains
or a car battery can be obtained from yourdealer.
The mains switch is mounted on thispanel and will switchpower
to both deck and amplifiers. Also mounted onthe mainsadjust-
mentpanel isa device known asa " Humdinger." This control is
preset atthe factory and further information onitmaybe found in
the Glossary.
LOADING THE TAPE
Before loading the tape forthe first time, remove the headcovers
in order to familiarise yourself with the position ofthe components,
the working ofthe pressure pads and pinchwheel. The upper
half of headcover isa pressed fit, and needs only tobe lifted from
its retainingposts; the lowerhalf is held in position bytwo screws.
To loadtape, place full reel on left-handspindle and thread as
shown onthe diagram(Fig. 2). With the tapecorrectlythreaded,
give the deck a trial run preparatory to making a recording,thus
familiarising yourself with the switchingoperations.
When the right-handswitch onthe deck is operated(record/play-
back) the tape will be transported from left to right across the
erase and record/playback heads ata speed dependent onthe
size of capstan sleeve inuseandthe setting ofthe speed switch.
The left-handknob isfor rewinding or winding onthe tape at high
speed, and will onlyoperate ifthe record/playbackswitch isinits
STOP position.

Al, A2,A3 Tapeguides
B Erase head
C Tapecontactrelease pin
Dl Retainingposts for upperhalfheadcover
D2 Retainingposts for lower halfheadcover
E Record/playbackhead
F Azimuth adjustmentscrew
G Capstanshaft
H Capstansleeve
J Adjustabletapeguide
AlC B
K Pinchwheel
LI,L2 Pressure Pads
M Take-up pin
N Pressure pad operating lever
O Crescent-shapedlever
P Pause control
R Superimpose control
S Pressure pad spring
V -jV' freemovement
W Supplementaryguide pillar
Fig. 2. Head layout and tape
lacing diagram

SPOOL RETAINING SCREWS
Screws are supplied for retaining the tapespools onthe hubs.
Whilst itisnot essential to fit these screws whenrecording, or
replaying the tape,theyshould be used whentransporting the
machine in order to hold the spools in position.
Should the screws be omitted duringfastwind or re-wind, itis
inevitable that a certainamount of vibration ofthe spool will occur.
Adjustable tape guide
In order to enable spools of variedtypes tobe used without the
edge ofthe spool fouling the tape, an adjustableguide is fitted.
Adjust as required by releasing the lower milled circular nutand
raising or lowering the guide by rotating the upper portion.
Finally, ensure that the lower lockingscrew is re-tightened.
Speed-changeswitch
This three-position switch gives speeds of:
(a) with largediameter capstan sleeve—IS, 7^, 3£ i.p.s.
(b) with smalldiameter capstan sleeve—7^-, 3£, If i.p.s.
Thisswitch does not rotate through 360°. The figures above the
switch areforuse with the smaller sleeve andthe lower with the
larger sleeve.
The machine is supplied with the large capstan sleeve in position
and the smallcapstansleeve fitted toW the supplementaryguide
pillar.
The sleeves are retained onthe capstan shaft with grub screws.
Ensure screw is tight, or speed fluctuations will occur. (NOTE: The
capstan sleeve should be fixed with the grubscrewnear the deck
plate,allowing £" clearancebetween endof sleeve and deckplate.)
RECORDING SEQUENCE
1 After ascertaining that the mainsadjustmentplug atthe rear
of the machine is correctly setto suityour mains voltage,
connect the machine tothe mains supply and switch on
(recorder mains switch isonthe same panel ofthe power unit
as the mains adjustmentplug).
2Fit reel of tape to left-hand(feed)spoolholder and lace the
tape asper diagram(Fig. 2)tothe emptytake-upspool (right-
hand),ensuring that the " sensitive " side ofthe tape faces the
heads. (Most tapes have a " glossy " side anda " dull " side—
itisthe " dull "-side which is coated with iron oxide andisthe
sensitive side).
3 Select recording speed and adjust the frequencycorrection
switch (B, Fig. I) to match. (Thefaster the tape speed the

better the recordingquality. If quality isnotso important,
then a lower speed maybe used to allowlongerrecording
periods per tape.)
4 Insertmicrophone jack plug into microphone input socket or,
if recording from radio,couple the radio tothe radio/gram
socket. (See special noteregardinggramophonepick-ups in
" Hints for ImprovingRecording " section.)
5 Switchamplifier to record and adjust the volume control
until the loudest(peak)signal from radio or microphone
causes the magic eye bars to justmeet or,ifa meter is fitted
in lieu ofeye (seenote on zeroingmeter inthe Glossary—
" Modulation Level Indicator ") until the needle rises to " 7 "
on the dial(i.e. tothe left-handedge ofthered portion ofthe
scale).
6 Note the position ofthe volume control and then turn it fully
anti-clockwise to minimum.
7Now depress the button near the deckrecord/playback
switch and turn thisswitch tothe " Record " position.
8 Advance the volume control to positionnoted in6and record-
ing will takeplace.
Ifthe superimpose control is inoperative,i.e. itissetto allow
the erase pressure padto press the tape tothe erase head, any
signals which have beenpreviouslyrecorded will be erased.
(See note on " Superimposing " inthe Glossary.)
10 Onemay hear the signalbeingrecorded on headphonescon-
nected tothe monitor socket.
11 Asthe recordingproceeds, onemay omit certainitems, for
example, announcementsbetween musical items ina broad-
cast, by temporarilyhalting the tapemovement by operating
the pause control. (Fade outthe signal by turning down the
volume control—operate pause control and afterreleasing
this control forthe continuance ofthe recording, advance the
volume control toits originalsetting.)
12 To stop the machine, switch rhe deckrecord/playbackswitch
to the central " stop " position.
13 When the whole ofthe tape has passed tothe take-upspool,
thisreel maybe inverted and transferred tothe feed side in
order that a further recording maybe made. (Seenote on
" Twin Track " inthe Glossary.)

PLAYBACK SEQUENCE
1 Once a recording has beenmade itmaybe replayed any
number of times until you decide to erase it. (Erasure is auto-
maticallyaccomplishedwhen another recording is made unless
superimposing isin operation.)
2 Place the recordedtape onthe feedspool (orifyou havejust
finished a recording session, rewind the tape ontothe feed
spool) and lace itto take-upspoolexactly asfor recording
purposes.
3 Switchamplifier to playback(playback indicator will light).
Turn volume control to minimum. Select speed of deck to
coincide with recording speed and similarly set frequency
correction switch.
4 Turn the deckrecord/playbackswitch to playback.Advance
volume control and adjust tone control as required. (The
frequency correction switch maybe adjusted toany position
desired buta " flat " response will be obtainedwhen itisset
tothe positioncoinciding with the deckspeed.)
5 Shouldplayback be required onan external speaker,simply
plug the externalspeaker into the appropriate socket ofthe
amplifier. (Internal speaker will be automaticallydis-
connected.)
6An external amplifier maybe used with the recorder by con-
necting itto either the(a) monitor socket and adjusting the
recordervolume control tothe requiredlevel, (b) co-axial
socket onthe amplifier chassis. The signal at this socket is
not governed bythe recordervolume control. (Normally this
socket is used with externalhigh fidelity pre-amplifiers and
amplifiers andis situated atthe rear to enableunobtrusive
connection tobe madewhen the recordingamplifier isin-
stalled ina " permanent " hi-fi installation.)
Ifitis desired to mute the internal loudspeaker when
operating as(a) above, insert a jack-plug which hasa 15 ohm
resistor wired across it into the external speaker socket.
WARNING—Do not mute with an open-circuited jack-plug
or damage will be caused tothe amplifier.
STRAIGHTAMPLIFIER
If the function switch is turned to " Amplifier " the amplifier only
will be available for reproducingsignals from radio tuner, pick-ups
and microphones. It should be noted that when a microphone is
used in close proximity toa loudspeaker, " acousticfeed-back "
(howling) will occur—therefore alwaysensure that the micro-
phone and speaker area considerabledistance apart.

Hints for improving recordings
MICROPHONES
Seldom isanyone type of microphone suitable for every circum-
stance andwe recommendthey be used as follows:
Ribbon: For highquality " live " musical recording
(indoors).
Dynamic (moving coil)—For indoor and outdoor use:
speech, music,etc.
Crystal—Principally for speech recordings.
RECORDING FROM MICROPHONE
Avoidplacing the microphonenear the motor ofthe taperecorder.
Wedonot recommend that the microphone be placed onthe
same table asthe tape recorder whenrecording.Earth the
machine ifthe microphone is used with a longercablethan that
supplied. This will avoid excessive A.C. hum.Only use screened
extension cables (co-axialcable as used forTV aerial leads is suit-
able).Alwaysensure that microphonecable is correctly connected
tothe jack plug—broken leads or reversedconnections will give
loud hum. Ifa low impedancemicrophone is used a matching
transformer will be required.
Donotrubthe hand or fingers onthe case ofa microphonewhilst
recordingotherwise " noise " will be recorded.
Endeavour to persuade people to speak oneata time andnotasa
group because a microphonerecords allit " hears " and cannot
discriminate ascanthe humanear.
RECORDING FROM RADIO
The bestrecordings will be obtained from FM-VHFtransmissions.
Donot record from a radioreceiver by means ofa microphone if
one ofthe following methods canbe employed:
(a) Record from extensionspeakersocketofradioreceiver.
(b) Record from the diode output ofthe radio receiver.Your
radio may requiremodification ifno diode output socket is
fitted. Your localdealer can advise you.
Always use screenedcable to coupleradio to tape recorder.
Always consultyourdealerbeforeusing an A.C./D.C. radio orTV
receiver which hasno extensionspeakersocket. The recording
signal source may requiremodification to enable the receiver tobe
used without risk of electricshock.

Always ensure that any plugs or connections are secure otherwise
intermittent crackling maybe produced.
PAUSE CONTROL
Immediately prior to using the pause control, turn down the
volume control. Conversely, revert to normalvolume as soon as
pause control is released. A little practice will soon enable the
user to makerecordings of excellentquality ata uniformsound
level with all unwantedmaterial omitted.
CARE OF HEADS AND GUIDES
Any accumulation of dirt or oxideparticles from the tape will
preventgoodrecordingsbeingmade.Periodically,therefore,
clean the working surfaces of both heads with methylatedspirit
applied with a small camel hairbrush.Take special care notto
scratch the surfaces ofthe heads. The tapeguides and capstan
shouldalso be periodicallycleaned with methylatedspirits to
removeoxidedeposit. Access to heads and tapeguides is available
merely by removing the mouldedcovers.
SELECTING AN EXTENSION LOUDSPEAKER
The choice ofa loudspeaker isa verypersonal thing, andwe
suggest that the listenershouldendeavour to hear a variety of
makes (within his pricerange), inuse with the taperecorder.
Ifthe speakers canbe heard within the listener's own home, so
much the better, as roomacousticsmust be taken into account.
RECORDING FROM GRAMOPHONE PICKUP
It should be borne in mind that moderngramophone discs are
deliberatelyrecorded with an attenuated(reduced) bass response
and an accentuatedtreble response compared with the original
sound.
Therefore, if satisfactorytaperecordings aretobe made,suitable
frequency compensationmust be incorporatedbetween the
gramophonepick-up andthe taperecordingamplifier to reverse
the disc's recordingcharacteristics.
Such frequencycompensationcircuits are incorporated in high
fidelity pre-amplifiers and thosepeople possessing such equipment
should record from gramophone discs onlyafter the signal has
passed through their hi-fi pre-amplifiers.
PICKUPS
Disc recordings from domesticradiogramsshould be taken from
the extension speaker sockets ofthe radiogram in order to take
advantage ofany frequencycorrectioncircuitsincorporated
therein. Shouldyourradiogram or recordplayer NOT have
extension speaker sockets, donot attempt touseitin conjunction

with your tape recorder before consulting a qualified electrician or
dealer.Many record players are dangerous touse unless fitted
with isolatingtransformers to preventelectricalshocks.
Mostmanufacturers of gramophonepick-ups will supply, on
request,details of frequency correction circuits foruse with their
products—and to avoid any misunderstanding, one should quote
the sensitivities and impedances ofthe amplifier with which a
pick-up istobe used whenapplying for information. Inthe case
ofthe BrenellMark 5 Series 2, quote:
" 2 mV into I megohm "
and " 80mV into 220k ohms."
Please note that permissionmust be obtained from the gramo-
phonerecordmanufacturerbeforetaperecordings are made from
discs. Failure to obtain permission isa breach of copyright.
-~T - ~ ~
When stopping the tape, the re-wind switch must
be brought quickly tothe central position in order
to allow instantaneous action by both brakes.
(An alternative method isto switch—very quickly
indeed—from the re-wind to the wind position (or vice
versa), thus transferring the power from one motor to
the other and achieving a gradual slowing down of the
tape, then, just as the tape movement is about to change,
turn the sw'tch to the central 'stop' position. This
method requires a little practice but is mentioned at the
request of a.number of people, who, having learned to use
it, prefer it to the abrupt arresting of the tape movement.)
Fig. 3
POWER SUPPLY
COMPENSATED LOW-LEVEL
OUTPUT SOCKET
10

Incorporating the Mark 5 Series 2 Recorder
into a permanent Hi-Fi installation
The Mark 5 Series 2 taperecorder is oftensold inthe threemain
units:
tapedeck
amplifier
power unit
foruse with, andfor installation into, a high fidelity console.
As all three units are coupledtogether by means of non-reversible
plugs and sockets (no solderingrequired) the addition of tape
recording facilities to exisingequipment is greatlysimplified.
DECK MOUNTING (Masksize isfx 12 )
The tapedeckshould be mounted HORIZONTALLY for best
results.
An aperture of I4"x 10^" ina mountingboard will allow the deck
to " drop through " until the deckplaterests onthe board.
Rubbergrommets or other rubbercushioningshould be fitted
between the deckplate andthe mountingboard.
(Beforeactuallymounting,remove the mask from the deck to
gain access tothe four holes for fixingpurposes.)
The deckshould be mountedapproximately £•" clear ofthe board
to facilitateventilation.Clearancebelow the deckplatemust beat
least 5".
8^" reels of tape will overlap the deckplate
IJ" tothe rear and
Ij" on both sides.
AMPLIFIER MOUNTING (Masksize 151 x41)
An aperture I2j"x4" will enable the amplifier to " drop through "
a mounting board until the maskrests onthe board.
Fixing isby means oftwo screws through the mask.
The amplifier maybe mounted atany angle.
POWER UNIT MOUNTING
The power unit is separate from the amplifier in order that itmay
be sited to induce the minimum A.C. hum into the heads andthe
II

amplifier.Therefore,aftermounting the deck and amplifier, the
three units will be coupled together, a loudspeakerattached and
the power unit movedaround until the position for minimum hum
is found.(See note on " Hum.") Fixing is thenaccomplished by
means of screws through the holesprovided.
HUM
It should be noted that hummaybe introduced from:
a mains transformer
" earth " loops
and thereforecertainprecautionsmust be taken and experiments
made should excessive humbe encountered.
Hum from mainstransformers maybe introduced into:
the tape heads
the recording/playbackamplifier
the cables from heads to amplifier
the cables carrying the signals toand from the amplifiers.
The Mark 5 Series 2 power unit hasa special low A.C.radiation
mains transformer. Beforescrewing the unit into a permanent
position the deck,amplifier and power unit should be coupled
together (deck and amplifier in permanentpositions), anda loud-
speaker plugged into the amplifier.
Now connect the equipment tothe mains supply,switch the
amplifier to playback andsetthe volume and tone controls to
maximum.
Adjust the humdinger onthe power unit for minimum hum—if no
definite position canbe ascertained, setit mid-way.Move the
power unit (beingcareful notto touch any components ora shock
may be received) toa position in which the minimum humis heard
from the loudspeaker,thenscrew the power unit down in this
position. (If thisposition is inconvenient forthe operation ofthe
mains switch, putthe switch tothe " ON " position and instal
anotherswitch ina moreconvenientposition, such asonthe deck
mounting board.)
Now switch onthe mainamplifyingequipment you will be using
with the taperecordingequipment and listen forhuminthe
speaker connected tothe playback amplifier. Should thehum
level rise with the switching onofthe mainamplifyingequipment,
it will be necessary to move the unit in which the mainstransformer
is situated (or move the tapedeckand/or amplifier).
COUPLINGAMPLIFIER TO HI-FI EQUIPMENT
The co-axialsocket onthe rear ofthe Brenellamplifiershould be
coupled tothe appropriate input socket ofthe hi-fi pre-amplifier
using goodqualityco-axialcable.
It should be noted that the signal from the co-axialsocket is
frequency corrected and must notbefed into a " tape input "
socket inthe hi-fi pre-amplifierwhich is designed for direct connec-
tion to a tape head. Ifthe onlysocketmarked " tape " is unsuitable,
12

couple tothe " extra " or " auxiliary " socketdesigned to receive
a " flat " or compensatedsignal.
Should the strength ofthe signal from the Mark 5 amplifier betoo
high and there isnota presetgain control incorporated inthe hi-fi
pre-amplifier, the signal must befedviaa screened volumecontrol
(value 50k to 100 k ohms) or attenuator.
(a) To Record
Follow the earlierinstructions on thissubject in thisbooklet,
bearing in mind that a signal for recordingpurposes maybe
obtained from either the loudspeaker output ofthe hi-fi
amplifier or from the "record" socket ofthe hi-fi pre-amplifier
(most pre-amplifiers have thisprovision).Microphones will be
plugged directly into the recordingamplifier.
(b) To Replay
Tape recordings maybe replayed via hi-fi amplifyingequipment
by connectingeither (a)the co-axialsocket or (b) the monitor
socket onthe Mark 5 Series 2 amplifier tothe hi-fi pre-
amplifier, ifthe outputfrom (a)is insufficient. Output level
of(b) will dependupon the adjustment ofthe playback
amplifier'svolume control.
EARTH LOOPS
Hum may be introduced into amplifyingequipment by having too
many earthpotentiallinking cables anditis thereforesometimes
necessary to ensure that only one piece ofthe installation is con-
nected tothe earthterminal ofthe mains supply installation—
one mustexperiment by removing all earth return leads and con-
necting oneata time to find which gives the condition of minimum
hum.
These testsshould be carried out with:
all equipmentswitched on
tape amplifierlinked to externalamplifier for playback
purposes
volume levels set high, butnotat maximum.
The cable used for linking the tapeamplifier and mainamplifier or
pre-amplifiershould bea goodquality co-axial type as used for
TV aerial leads.
The signal from the co-axial socket onthe Mark 5 Series 2 amplifier
is not affected bythe volume control setting of thisamplifier and
thereforethisvolume control should besetto minimum.
Ifthe Mark 5 Series 2 amplifier isnot used with a loud-
speaker, itis essential to fit a 15 ohm wire wound
resistor asa dummyload in lieu ofthe speaker. This
resistor maybe permanently fitted across the extension
speaker socket ofthe tapeamplifier, or fitted toa jack
plug inserted into the extension speaker socket.
Fig. 4. Socket with resistor fitted
15 J~\.
13

Maintenance
TO CLEAN
For the continuedefficientoperating ofthe machine, itis essential
to ensure that the heads, pinchwheel and tapeguides, are clean
and freefromtapeoxide.
A very thin film of dirt or oxide onthe heads will seriously mar
the frequencyresponse and reduce the volumelevel, whilst oxide
onthe pinchwheel and guides may cause tape slipping—apparent
tothe listener asa variable change in pitch ofthe recordedsounds.
We recommend the cleaning kit marketed by Messrs. METRO-
SOUND M.F.S. Co. Ltd., I9a BuckinghamRoad,London,N.I, and
known as KLENZATAPE.This kit will enable the heads tobe
quickly and efficientlycleaned.
The tapeguides and pinchwheelshould be cleaned with methy-
latedspirits, but careshould be taken to prevent this spirit being
spilt onthe plastic head covers.Methylatedspirits may also be
used ona lightlydampenedlinen cloth for cleaning the heads.
REMOVAL OF AMPLIFIER
Two domedscrews FI-F2 (Fig. I)are used to hold the amplifier
inthe cabinet, andthe removal of thesescrews will enable the
amplifier tobe lifted from the cabinet for examinationand, if
necessary, operation whilst " live."
Donot disconnect the amplifier from the power unit unless
the mains switch isOFF otherwise excessive voltage will
build upinthepower unit and damage will occur.
REMOVAL OF DECK
The deck is covered bya steelmaskwhichmust be removed to
gain access tothe four boltswhichclamp the deck tothe mounting
brackets.
DONOT remove the four screws from the sides ofthe cabinet—
these screws retain the deckmountingbrackets in position. The
mask maybe lifted from the deckafterremoval ofthe deckknobs,
adjustable guide,plastic head covers andthetwo smallscrews
near the spoolholders. When lifting the deck,careshould be taken
to avoiddamaging the cables coupling amplifier and deck.
REMOVAL OF POWERUNIT
After removal ofthe amplifier and deck, the power unit will be
14

readily accessible andmaybe entirely removed from the cabinet
by removing the clampingscrews. (Be sure to replace spacers
when refitting.)
The power unit must notbe operated unless loaded bythe
amplifier, otherwise high voltages will build upand cause
damage.
OILING
The motors, flywheel, idler wheel and pinchwheel are fitted with
the " oilite " oil-retaining bearings and therefore will seldom
require oiling. Not morethan one drop of thin machine oil will
be needed to each bearing per 1,000 hours'use.
Oil must notbe allowed to contaminate the rubbertyres ofthe
idler and pinchwheels.
Oilonthe periphery ofthe flywheel will cause the tape speeds to
become erratic.
BRAKES
Mechanical braking is employed; cork-lined levers act upon the
spoolholderdrums.
BRAKE ADJUSTMENT
Should tapespillageoccur(whenusingreels of equal size) check
adjustment of brakes,whichshould beas follows:
With rewind and record/playbackswitches to " STOP,"adjust the
gap betweenbrakelevers andthe4 B.A. adjustablescrews in
actuatingbar, to -^".
Adjustment of thesescrews canbe carried out after releasing the
lock-nuts.Always tighten lock-nutsafterwards.
Should spillageoccurwhen thegapis correct, shorten the brake
spring by approximately £".
(NOTE that when using reels of unequal size,centrifugalforces will
be unequal and tapespillage may occur.)
STABILISER BRAKE
This isa smallbrakewhichoperates onthe feed-spoolholder drum
to stabilise the tapefeed on record and playback.
Itis essential that thisbrakeshould have very light pressure onthe
feed spoolholderotherwise thewow content will rise asthe tape
nears the centre ofthe reel.
The pressureshould be justsufficient to prevent a full reel of tape
unwindingjerkilyduringrecordandplayback.
MOTORS
Threemotors are employed onthe Mark 5 Series 2 deck—
hysteresis synchronoustype for driving the capstan, 5 watt shaded
pole for rewinding, and3 watt shaded pole for take-up.
15

MOTOR TEMPERATURE
These motors are designed to operate at high temperatures—
50°C plus ambient.
SPEED CHANGE SWITCH
This three-positionswitch gives speeds of:
(a) with I" diameter capstan sleeve—IS, 7^, 3J i.p.s.
(b) with j" diameter capstan sleeve—7\ 3|, IJ i.p.s.
(See note on " Capstan sleeves.")
Important: should the user desire to dispense with the 15 i.p.s.
and permanently usethe small capstan sleeve, giving speeds of IJ,
3f and 7^ i.p.s., the cable between speed switch and resistor RSI
should be removed;this will enable the take-up motor to operate
at a lowertemperature inthe highest speed position.
(NOTE: At 15 i.p.s. full mains power is applied tothe take-up
motor to givefaster initial take-up and preventtapespillage.)
CAPSTAN SLEEVES
Two sleeves are provided of approximately I" and ^" diameter. The
I", used in conjunction with speed switch, gives speeds of 15, 7j and
3J i.p.s., whilst the \" isfor speeds of 7^, 3| and IJ i.p.s.
(See note on " Speed ChangeSwitch ")
The sleeves are retained onthe capstan shaft with grub screws.
Ensure screw is tight, or speed fluctuations will occur.
(NOTE: The capstan sleeve should be fixed with the grubscrew
near the deck plate,allowing £" clearance between endof sleeve
and deckplate.)
These illustrationsshow how simple itisto gain
access toall parts ofthe BrenelI Mark 5 Series 2
deck simply by removing the maindrive motor
plate.
A Take-up motor
C Maindrive motor
D500 ohms 10 watt resistor
F Feed motor
G Suppressorunits
16

To gain access to idler pulley (Z) remove
screws N andBand swing speed-changing
mechanism so that idler is clear of motor
plate.
Xisthe steppedpulley.
Uisthe lower bearing forthe capstan
spindle.
Fig- 6 v
H Mechanicalbrake
K Speed changeswitch
M Rewindswitch
P Flywheel
Fig. 5 ^
Q Headleads,anchoring strip
S Recordplayback switch
T Suppressor units
U Lower bearing—capstan spindle
17

Fig. 7
To extract main drive motor plate and speed-changemechanism
(Y),loosenscrews G andT,and removescrews E,O,R,V andW,
circlips J andL,and suppressorunits G andT.See Fig. 5.
1 isoneofthetwo brakeadjustmentscrews.
Idler wheel retaining circlips and
washer.
v Fig. 8
18

PRESSURE PAD RELEASE MECHANISM
An adjustablecrescent-shapedlever(seeFig. 2) controls the move-
ment ofthe leverreleasing the pressure pads (Nin Fig. 2).
This is carefully setup before the deck leaves the works, butin
case adjustment is required the following setting-upprocedure
should be adopted:
With I" diametercapstan sleeve in position, switch to playback
and adjust the crescentlever so that when the pressure pads meet
the headfaces,approximately -fa" freemovement ofthe releasing
baris possible(see V on Fig. 2).
ERRATIC TAPE SPEED
Will be caused ifOILis allowed to accumulate onthe flywheel,
idler or motor pulley.
FAULT FINDING
Loss oftop response and/or output from record/playback heads
and incompleteerasure:
The above condition canbe caused bythe tapebeingunable to
make intimate contact with the face ofthe record/playbackhead
orthe erasehead owing toa build-up of oxidedust.
REMEDY: Cleanhead faces with soft,clean cloth dampened with
methylatedspirits(NOTPETROL). Atthe same time clean the
tapeguides,tensioningpins and capstan sleeve.
Check for distortion of pressure pads and/orarms.Check
springtension of arms. The armsshouldmovefreely on their
posts.
WOWAND FLUTTER
Listed below are some ofthe possible causes ofwowand flutter:
(a) Driving members dirty and/or greasy
(b) Eccentricpinchwheel
(c) Stabiliserbrakeunder too great tension
(d) Idler wheel fouling steppedpulley
(e) Loose capstan sleeve
(f) Tight bearings of flywheel,pinchwheeland/or idler.
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REMEDIES FORWOWAND FLUTTER
(a) Clean with soft cloth dampened with methylated spirits:
the flywheel rim
capstan sleeve
tape guides
head faces
stepped motor pulley.
(b) Changepinch-wheel;avoidcontact with oil.
(c) Adjust the pressure ofthe stabiliserbrake tothe minimum
amountrequired to prevent the tapespoolunwinding ina
jerkymannerduring the record or playbackoperations.
Adjustment is effected by releasing the4 B.A. fixing nutand
resetting the position ofthe brakelever.
(d) Adjust height of steppedpulley to ensureonly one section is
operativeaccording to speed in use.
(e) Ensure that fixing screw is tight.
(0 Usually dueto dirt—clean and lightly oilthe bearings.
Specification
TAPE SPEEDS: l|, 3|, 7^ and IS i.p.s.
MOTORS: Three(SynchronousHysteresistype for driving
capstan).
WOWAND FLUTTER:
Less than0.05% at 15 i.p.s.
0.1% at 7± i.p.s.
0.15% at 3f i.p.s.
0.25% at IJ i.p.s.
Please note, thesefigures arefor Record/Replay andNOT Record
only.
RECORD/PLAYBACK FREQUENCY RESPONSE:
15 i.p.s. 40 c/s to over 15 kc/s ±2 dB
7£ i.p.s. 40c/sto 14 kc/s ±3dB
3| i.p.s. 40c/sto 11 kc/s ±3dB
IJ i.p.s. 40c/s to 6 kc/s ±3dB
Measured at Ext. Amp Socketacross 47k ohm load.
AMPLIFIER RESPONSE: 40c/sto20 kc/s ±3dB.
BASS CONTROL: 9 dB variation at65 c/s.
SIGNAL/NOISE RATIO: Unweighted—including hum—45 dB.
SENSITIVITIES:
FOR PEAK MODULATION A MINIMUM SIGNAL OF:
MICROPHONE: 2.0 mV (Impedance I Megohm).
RADIO: 80mV (Impedance 220k ohms).
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