3M DELTA Series - Reproducers

SECTION VI - PRINCIPLES OF OPERATION
A POWER SUPPLY SYSTEMS
1. Reproducers
Delta Series components utilize multiple voltage
power supplies to operate the solenoids, amplifiers,
logic and lamps. Main AC power is connected to the
unit via the power cord and a rear-panel instrumen 
tation-type connector. The power is routed through
a fuse holder capable of using either American 3-
AG sized fuses, or 5 x 20 mm fuses commonly used in
Europe. A dual primary toroidal power transformer
is mounted inside the mainframe, and may be used
on either 120 volt AC, or 240 volt AC mains. Mains
voltage selection is accomplished by wiring the
primaries in parallel (120 VAC) or Series (240 VAC).
All units may be operated on either 50 Hz or 60 Hz
voltages.
Transformer secondary number 1, Orange-
Black-Orange, supplies low voltage AC to the full
wave rectifier: (DI & DII — CR 512. CR 513; Dill — CR
705, CR 706) and is filtered by the input capacitor, a
15,000 mfd electrolytic. DC voltage at this point is
approximately + 14 VDC This voltage is passed to the
rear panel for further use in the Record Amplifier
and to a 7805 voltage regulator. Regulator ouput
is +5 VDC It is used for operation of the logic circuits,
illumination of internal lamps, and is available at
the rear panel for use with external lamps as well.
Secondary number 2. Red-Yellow-Red, runs the
amplifier power supplies. Medium voltage AC is
supplied to full wave bridge rectifier: (DI 8c DII — CR
508, 509, 510, 511; Dill — CR 715, 716, 717, 718). The
bridge outputs both + and - voltages. These vol 
tages, approximately +30 volts, are fed to two 2200
mfd filter capacitors (6800 in Delta III units) and
then to two 15 volt regulators, one +15 volt 7815 and
one -15 volt 7915. The regulated ±15 volt supply volt 
ages are used to run amplifiers in the reproducers.
Unregulated DC supplying the 5 volt and +15
volt supplies is routed through the rear panel inter 
connect for supplying separate regulators used in
the Delta IV Record Amplifier,
2. Record Amplifiers
Unregulated DC from the reproducer (+14 volts, and
+30 volts) is brought in via the interconnect cable
and the rear panel connector. Record Amplifier
power supplies are similar to those used in the
reproducers. Unregulated DC is supplied to three
IC voltage regulators, a 7805, 7815, and 7915, and
connected to their respective loads. The +5 volt
supply operates the logic and lamps, while the ±15
volts supply is used in analog circuits.
It is important to remember when servicing that
failure of one supply may affect other supplies even
though they have separate regulators and filters. It
should also be noted that a low-voltage/high cur 
rent condition will be created if the toroid trans 
former "top mounting plate" is electrically connected
to ground. Toroid transformers are highly efficient
devices and radiate little heat or field when in
operation. Irrespective of this, an appreciation of
their operating characteristics will facilitate servic 
ing.
DC Current
In Milliamperes
TYPICAL VOLTAGE AND CURRENT REQUIREMENTS
+ 15V -15V +5V
Delta I. II
Motor
700
Motor Control
60
Play Logic
500
Lamps
300
Cue Amplifiers 45 45
Play Amplifiers
135
135
Relays
180
Total 880
180
1040
Delta III
Motor
700
Motor Control
60
Play Logic
500
Lamps
300
Cue Amplifiers 135 135
Play Amplifiers
405
405
Relays
540
Totals
1240
540
1520
Delta IV
Lamps
180
Record Logic
218
Amplifiers 225 225
Total 225 225
398
Currents indicated are "typical," and will vary from
machine to machine, depending on model varia 
tions, accessory loading, and external conditions.
6-1