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LANSING
1270 POWER AMPLIFIER
OPERATING
INSTRUCTIONS
No user-serviceable parts inside. Hazardous voltage may be en¬
countered within the chassis. Installation and Service information
within this document is for use only by ALTEC sound contractors, factory authorized
warranty stations and qualified service personnel.
II est enjoint a Tutilisateur de ne pas reparer lui-meme les pieces
IMPORTANT:
.
'
„
.
' . . \ t
,
internes de l appareil, des courants a haute tension pouvant pas¬
ser a I'interieur du chassis. Les renseignements inclus dans ce document son I destines
uniquement a I'usage des installateurs agrees des systemes acoustiques ALTEC, des
centres de reparation sous garantie autorises, ainsi que du personnel d'entretien
qualifie.
INTRODUCTION
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
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.
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.
Item
Name
Function/Description
Peak/Error
Indicators
Protection
Indicator
POWER
Indicator
POWER Switch
CHANNEL
Volume
Controls
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.
ALTEC
LANSING
Specifications and components subject
to change without
notice.
Overall performance will be maintained or improved.
1515 S. Manchester Ave., Anaheim, Calif. 92803
42-02-045589-01
LITHO IN U.S.A. 681-1M
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