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1270
User Manual
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User Manual
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Altec Lansing 1270 User Manual

1270 POWER AMPLIFIER

OPERATING

INSTRUCTIONS

INTR0DUCT10N
The ALTEC LANSING Model 1270 Power Amplifier provides continuous high power demand where uninterrupted operation is requisite. Designed to protect itself and the acoustic elements it drives, the Model 1270
represents 800 + watts of controlled power. Two channels may be operated independ ently, in parallel or in bridged configuration to deliver up to 400 watts per channel at
less than 0.05% THD from 20 Hz to 20 kHz.
Peak Error Computer
CAUTION: ,
within this document is for use only by ALTECsoiind contractors, fnclonj authorized liHirmnty stations and quaiified service personnel.
IMPORTANT: . , \ ,
sera l'intérieur du châssis. Tes renséignenien ts indus dans ce doainient son t destinés uniquement à l'usage des installateurs agréés des systèmes acoustiques ALTEC, des centres de réparation sous garantie autorisés, ainsi que du personnel d'entretien qualifié-
No user-serviceabte vorts inside. Hazardous uoltme may be l'ji- cauniered witkiit fhedmssis, InstaHahon and bervwc mjormatum
Load Protection The load is protected from transients dur
ing startup and shutdown of the amplifier. During startup, the load remains discon nected through a relay during a three-
FRONT PANEL CONTROLS AND FEATURES
second delay period. During shutdown or loss of power, the load is instantaneously disconnected by the relay. The load is simi
larly protected against amplifier failure,
such as dc voltage at the output.
The amplifier is provided with a peak/error computer that compares channel input and
output signals and detects any output
errors. Detection of any peak/error causes
the appropriate peak/error indicator to illu
minate. Output anomalies detected include
excessive voltage, excessive current (load),
excessive slew rate, and any other signifi
cant difference between the channel input
and output signal.
Amplifier Protection
The amplifier output is continuously mon
itored to guard against excessive current drain. An instantaneous VI limiter restricts output to 400 VA ±45° phase shift. The amplifier is additionally protected against excessive operating temperature; logic cir cuitry automatically overrides low-speed fan operation and locks to the high fan speed mode. If operating temperature remains excessive, the load is discon nected by a relay and the protection indica tor illuminates. When temperature falls to safe operating conditions, the amplifier automatically resumes operation.
Item
Peak/Error Indicators
Protection Indicator
POWER Indicator
POWER Switch CHANNEL
Volume Controls
Name
Function/Description
Illuminate when excessive voltage, current or slew rate ap pears at the output terminals.
Illuminates when protection circuitry operates to prevent dam age to the amplifier or load.
Illuminated when primary ac power is applied to the amplifier.
Applies primary ac power to the amplifier. Adjust gain of LEFT and RIGHT channels. Rotate clockwise to
increase gain.

LANSING

Specifications and components subject to change without notice. Overall performance will be maintained or iTTzproLieci.
1515 S. Manchester Ave., Anaheim, Calif. 92803
42-02-045539-01
LITHÛ IN U.S.A. 68MM
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
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.
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.
The 1270 must be adequately ventilated to prevent excessive temperature rise. Max
imum rated ambient operating temperature is SS-C (131'F).
------------------
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.
REAR PANEL CONTROLS AND FEATURES
100V, 200V, 220V, 240V, 50/60 Hz Power Connections
Refer to Authorized
Altec Service
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.
SECURING SCREW
TRANSFORMER MODULE
INPUT RECEPTACLES
MODULE JACKS
CHANNEL INPUT RECEPTACLES
1b. Module Installed
Figure 1. Installation of 1270TM Module
WHT
Item
OUTPUT Terminals
INPUT Receptacles
LINE Receptacles
BRIDGE/ NORMAL Switch
COM Terminal GND Terminal
FAN Switch Fuse
Name
6 5
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.
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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