Altec Lansing 1270 - Manual (Page 2)

INSTALLATION
Rack Mourning
The 1270 may be installed in a standard
19-inch equipment rack, or in the 42526
Shelf Mount Cover Accessory for shelf use.
Vertical space required is 5V4 Rack instal­
lation is accomplished by using the appro­
priate four mounting screws supplied.
Ventilation
The 1270 must be adequately ventilated to
prevent excessive temperature rise. Max­
imum rated ambient operating temperature
is SS-C (131'F).
ELECTRICAL
120 Volt, 50/60 Hz Power Connections
Equipment supplied for domestic use is
provided with the power transformer
primary strapped for 120 volts. Specified
voltage rating is located on the chassis,
adjacent to the power cord. Verify that line
voltage is in accordance with specified volt­
age before connecting the 1270 to ac line
power.
100V, 200V, 220V, 240V, 50/60 Hz Power
Connections
Altec Service
------------------ CAUTION -------------------
Do not block the side ventilation
aperatures on either side of the main
frame. Allow at least 2" on each side
of the main frame to assure adequate
ventilation. Do not operate within a
completely
closed, unventilated
housing.
Refer to Authorized
Representative.
Input Connections
Unbalanced input connections to the
INPUT jacks are made with shielded single­
conductor cables terminated with standard
Vi-inch phone jacks. In preparing the cable,
the conductor is soldered to the tip of the
jack, and the shield is soldered to the
sleeve.
REAR PANEL CONTROLS AND FEATURES
6 5
Item Name
OUTPUT
Terminals
INPUT
Receptacles
LINE
Receptacles
BRIDGE/
NORMAL
Switch
COM Terminal
GND Terminal
FAN Switch
Fuse
Function/Description
Connect left (L) and right (R) channels to corresponding speak­
ers. Two pair of standard GR jacks have red ( -i- ) and black ( - )
polarity designations.
Accept cables from high impedance (nominal 15,000 ohms)
sources. Use standard ring and sleeve plug for left (L) and right
(r) receptacles.
Accept cables to connect other Altec Amplifiers in parallel.
Use standard ring and sleeve plug for left (L) and right (R)
receptacles.
Connects internal circuitry for independent or mono operation
(NORMAL) into a 4-ohm load, of bridge operation (BRIDGE)
into 8 ohms.
Provides connection to circuit common.
Provides connection to chassis ground.
Selects low (1) or high (2) fan speed.
Protects amplifier from excessive current drain. Replace only
with same type lO-ampere fuse, Refer to qualified service per­
sonnel if fuse blows repeatedly.
Balanced input connections are made with
the optional 1270TM Dual Balanced Trans­
former Input Module. Plug the 1270TM into
the INPUT receptacles of the 1270 and
secure the retaining screw. See Figure 1.
Cables terminated with XLR3-type connec­
tors are used to make input connections to
the 1270 TM module; wiring for the XLR3-
type connector is shown in Figure 2.
SECURING
SCREW
TRANSFORMER
MODULE
INPUT
RECEPTACLES
MODULE JACKS
CHANNEL INPUT
RECEPTACLES
1b. Module Installed
Figure 1. Installation of 1270TM Module
WHT
Figure 2. Wiring for XLR3-type Connector
Line Oul Connections
Connections to LINE OUT receptacles are
made with shielded single-conductor
cables terminated with standard 'A-inch
phone jacks. Vi/hen channels are operated
independently (stereo operation) a cable
must connect each channel of each addi­
tional 1270 amplifier connected in multipfe.
When channels are operated in the bridge
mode, only the left channel of each addi­
tional 1270 requires a connecting cable.
Output Connections
Output connections are made at the L and
R OUTPUT terminals. Figure 3 illustrates
connections for independent (stereo) opera­
tion and for bridged operation.
GND and COM Connections
The GND (chassis ground) and COM (elec­
trical common) terminals are used to cor­
rect unsatisfactory grounding conditions
and for establishing desired grounding
configurations.
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