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SPEAKER
l"L~TCHING
TR!ll:r8FORNERS
All house monitor sp",akers should have matching transfarDers.
These should be 45/50 ohms to voice coil.
The output impedance
of the monitor amplifiers is 4 to 16 ohms (8 ohDs nOL1inal). The
parallel cO::lbination of the sp83.kers should fall in this range.
Tho 47 ohm bc.ok loading resi.stors, nounted on the relay deck,
prevent the load from changi.ng .Ihen the speakers are muted.
REGULATED PO.TER
SUPPLY·iliD
FO',JER TE.':NSFORl1:GR
The power supply has
tviO
DC outputs •
A ·-37 V unregulated out-,
put for the cue-i.ntercom amp, and a '-30 V regulated supply for
all other circuits.
Transistors XQ4, XQ5, and XQ6 amplify any
Change in output voltage.
This sensing signal is then fed to
XQ2, • .;hich in turn controls the) vol tac:;e drop across XQl.
XQl
is in series with the output and maintains a constant voltage
with varying load and pOvier line.
Zener diodes CR9, CR10 and
CR11 provide, reference levels for the voltage sensing amplifier.
Overload protection is provided by XQ3 and the associated cir .. ·
cui try •
1'1aximun current out of the power supply is limited to
approximately 600 ma.
R12 provides for adjusting the output
voltage over a small range, to a110," for zener diode voltage
tolerances.
~i110n
instal1ilig the console, this voltage should
be checked and if necessary, R12 readjusted to give ·-30 volts
at the output
+
and - bus.
'I'he console pO\ver transformer ts
designed to LlOunt externally.
This prevents the hi.gh
hun
fL;ld,
. surrounding the
pO\i~r
transformer, from inducing a high hun
level into the
1m[
lev01 console circuits.
Three independent
28 volt windings are necessary to prov:;..de cOhlplete isolation
between each moni.tor a;;:plifier and the main console power supply.
NAINTEN~
On of the great advantages in the use of transistors is the
long life expectancy of seniconductor devices.
In this con-'
sole, high quality componcmts, conservatively rated, have been
conbined wit-h t-he latGst circuit techniques to give maxi.Llun
dependabili ty vlith a nininun of cme.rgency maintenance.
However,
even the finest equipnent L1ay becone erratic or
inop~rative
if '
not properly cared for.
\J0
strongly recoLlIlend that the station
engineer plan a routine preventive maintenance schedule and L1ake
every'effort to faithfully follow it.
VOLTAGE
NEASUR~~N~S
Average voltage readings are given on the schematic diagrams of
the various amplifiers.
It is reco=ended thilt, after the con-
sole is installed and operating sati.sfactorily, these readings
be checked and recorded on the schenatic.
This will provide
The Executive
6/26/62
-19-
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