Case
B:front panel
for stereo80 A AFU only but will acceptother
combinationsascase
A.
CaseC:
front panel
fortuneranddecoder
only,
room for PZ1or PZ6.
West Hyde
can supplya transformerfor the PZ8andall
hardware
for theamplifiercases,
which
willbe ready
punched.
Holesindicated$shouldbe %" (3mm)
diameter.The largehole
on the switch unit shouldbe 7o" (6mm)
and allotherholes
*"
(5mm).
See
page
31fortemplates
A3 Positioning the modules
A3.1.Preampand AFU, tuner and decoder
The positioning
of thesewill naturallybedeterminedby the cabinet
whichischosen.
TheStereo
80isthe modulewhich ismostusedandisthe heartof
the systemso this will probably
be placed
centrally,
with the other
modulesaround
it.
(e.g.
tunerand
decoderto the left,AFU io the
right).
Remember
that the input wiresto thesemodulesaresensitiveto
inducedhum so do not place
them wherethesewireswill pass
near
to mainstransformerandwiring,orto turntablemotors,or nearthe
outputs of the 240/760.
In
our layouts
(AB A AC) we keepallmainswiring
in the back
right (or left)hand corner
well awayfrom the preamp.
43.2.Z|0 and
260
Thetwo power amplifiersshould
be positioned
closeto eachother
(two can evensharethe same heatsink
block as shown in section
D89.2.2.1.Keepthem away from the input sockets,wiring and
connectionsto the preamplif
ier,
to avoid
interaction.
A3.3.Earth
point
A point should be chosenmid-way betweenthe 240'sor 260'sto
whichall
earth
wiresarerun,separately.Positionthissothat
wires
to terminals1 and
2 (and
3 on 260)
of theamplifiersareno longer
than3". Separate
wires
are
alsorunto theearth
point
from:
power suppry
-ve
speakersockets
mainsearth
AFU earth
Preamplifier
earth
Do not 'double
up' on anyof thesewires.
Itis
usuallyconvenientto
form
this
point
fromseveralsoldertags,as
we have,which arescreweddown to the chassisfor support (and
to makeelectricalconnectionto the chassis).lt doesnothaveto be
screweddown but, if it isnot,aseparate
wire shouldbe connected
from it to the chassis
(or
metal
earthing
foil).
Notein layoutAC we haveruna separate
wire
to earththe metal
heat fins of the Z40s - this of course
is not necessary
if a metal
chassisis used since earthing
will then be done automatically
throughthe mounting.
A.3.4.Power supply
TheP25,6
or 8 will be mountednearto the Z40sor Z60ssothat the
positive
andnegativewiresarenotlongerthan
about
6". Thislength
islesscriticalwiththePZSandmorewiththe PZB.InourlayoutAC
thesewiresareabout 12" long,
which issatisfactorywith PZ5.
ThePZSor6willalsorequire
positioning
sothat the transformeris
kept
awayfrominputandotherwiring
(or
itcaninducehum)andso
that mainswiresandconnectionsareneatandtogether.
ThePZ8isnotsocritical
- the
transformercan
bemounted
some
distance
from the PZ8
(there
areno mains
connectionson the PZ8
itself
).
lfthe + ve
and
-ve
wiresfromthe power
supply
aretoo long it can
causedistortion.lf this occursthen a second
point can be chosen,
similarto theearth
ooint
butisolatedfromthe
chassis.
A 1
000uF50V
capacitor
shouldbeconnectedbetweenthisH.T.
point
and
theearth
point,
and all H.T.wiresarenow run to the H.T.
point
instead
of
directto the power supplywhich now connectsthrough a single,
ionger
wireto r v€ H.T.
point.
A3.5.Mainswires
Mainswiring is
potentially
dangerous.lt has
250V
present
and if by
accidentthisis
appliedanywhereotherthanthe correctterminalson
the power supplyit will be destructive.
MainsLive
(Brown)connects
direct
to the fuse:
the otherconnect-
ionof the fuse
goes
throughone pole
of the on,/offswitchto the L
10
connection
on the PZ5or 6 or to the 240 volt input on the PZ8
transformer.
MainsNeutral
connectsthrough
thesecond
pole
on the switchto N
on the PZ5,/6
or to Ov on the transformer
primary
of the PZ8.
Mains
earth
(green/yellow)
connectsdirect
to the main earth
point
in
the
amplifier.lf a turntable
or othermains
powered
itemis
to be
used,operatedbythesameswitchasthe Project
80,thenthe mains
wire
shouldbe
takenfrom L
and
N on thePZS/6via
a suitable
plug
and
socketif required.
to its
mains
connection.
ON NO
ACCOUNT
MUSTANY MAINS
CONNECTION
BEMADE
TO
ANY OTHERMODULE
Because
of the
high
voltage,and
the
possibility
of inducing
hum,
mainswiring is bestkeptwell away from the rest of the amplifier.
Caremustbetakenif
themainsswitchis
to bemountedon the front
of the amplifier.
seealsosectionA5.3.
43.6. Output wiring
From
pin
9onthe240
orZ60 the outputwirecorrnects
(via
a2000uF
capacitor
on the 260 only) to the output socket, and to any
headphone
sockets
you may havefitted.
lf any of this wiring is anywhere
nearthe input wiring of the
preamplifier,
orany
othermodules,interaction
canoccur
assomeof
the
outputsignalwill
then
feed
backto the input.
Keep
outputwell
awayfrom
the input
and
alsotwistthe outputearth
and live
leads
together.
A3.7.Inputwiring
Shouid
usuallybe
screened
- but if it is
short
(4" or so)
anddoes
not
pass
near
any
mains
oroutputwiring,
screeningisnotnecessary.
Thus,
in
our
plinth
layout
we have
notusedscreenedwires
fromthe
tunerto the Stereo80, but we haveusedscreenedwire from the
pickup.
A4 Useof other modules in our layouts
44.1 740 or Z.60
The260
islonger
thanthe 240.lt also
requires
an additionalfairly
bulky
outputcapacitor
(see
sectionD.5).The output capacitoris
part
of theoutputwiringandmust
betreated
accordingly.
It shouldbe noted that there is no advantagein using the 260
instead
of the240
unlessa PZ8isused,
althoughwith l5Ospeakers
andaPZ6,
thesupplyvoltage
canbeincreased
to about40
to give
a
useful
power increase.
A4.2.
PZ5or6
Theseare
physically
and electronically
interchangeable.
However,
whenusing
a
PZ6,
additional
heatsinking
willberequired
(see
section
D6.4.).The
PZ6willresultin
aslightimprovemenr
inhumlevel
when
the
tuner
is
used.
A4.3.PZ8
ThePZ8isnot physically
or electrically
a replacementfor the PZsor
6 and the transformerscommonly availablefor the PZ8are large
(about
10
x 8 x Bcm).lfthetransformer
isto behousedinthe same
casethen this will needto be considerablylarger
than the PZ5l6
case.The PZ8must not be used
with Z40s
unlessitsoutput voltage
is reduced
{see
sectionEC6)
but if this is done it does resultin a
considerableimprovementin
performance.
The PZ8
alsoshouldbe chosenwhere sustainedhigh power
operationisrequired.PZSand6 aresmall
andafterawhile
getquite
hot at higher
powers.lt is, of course,
quite possible
to mount the
PZ8's
transformerremotefromthe PZB
proper.
A4.4.Project
60
modules
The
earlier
project
60modules
arecompatiblewith project
80except
thatthe Stereo60
gives
more
outputthenthe project
80preamplifier
sothegain
of the230
and250is lessthan that of the 240 and260.
However,the gain
of the 260has
been
kept
deliberatelylow so that
itis
stillcompatiblewith theearlierProject60.
When using
project
80controlmoduleswith 230
or250thegain
of
the
230
or50willneedto beincreased.
A4.s.tcl2
lt is
possible
to useanlC12instead
ot a240. The lC12
shouldhave
its
gain
setto 100
asexplainedin
theinstructions.
A4.6.
OtherModules
Thereare
othermakes
of modules
availableand it is orobablethat
mostof thesewill present
no problem
when usedwith Project
80
provided they use a similar power supply voltage and have a
negative
earth.Such combinations,
however,arebeyondSinclair's
