Telex ELECTRO VOICE CP 1200 - Handbuch (Seite 6)

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FRONT PANEL
This indicator lights when the power amplifier has been switched on. Causes for the
POWER-indicator not lighting are: the appliance is not connected to the mains
or the primary fuse is defective.
The PROTECT LED indicating that one of the internal protection circuits
against thermal overload, short-circuit, Back-EMF, HF-occurrence at the output,
etc., has been activated. The output relays interrupt the connected loads from
the power amps while input signals are interrupted as well, preventing the connected
loudspeaker systems and the power amplifiers themselves from being damaged.
Whatever caused the fault – e.g. a short-circuited speaker cable – needs to be reme-
died. In case of thermal overload you have to wait until the power amplifier automati-
cally regains normal operation.
The SIGNAL LED lights as soon as an audio signal of approximately 30dB below full
modulation is present at the output. The LED is dimmed when speaker cables are
short-circuited or a protection circuit has been activated.
The 0dB LED lights whenever the power amplifier is driven at its maximum. Higher
input voltage does not result in higher peak output voltage. In addition, the 0dB
indicator comes in handy when adjusting external limiters.
This indicator lights as soon as the integrated dynamic audio signal limiter is
activated and the power amplifier is driven at the clipping limit or generally at its
maximum capacity. Short-term blinking is not a problem, because the internal limiter
controlls input levels of up to +21dBu down to a THD of approximately 1%. If, on the
other hand, this LED lights constantly, reducing the volume is recommended to
prevent the loudspeaker systems connected from being damaged by probable
overload.
Detent potentiometers scaled in dB (steps of 1dB) for
adjusting the power amp’s overall volume. To prevent
distortion in mixing consoles connected to your CP-Series
amp, setting these controls to a value between 0dB and -6dB
is generally recommended. The dB-scale provides direct
indication of the control attenuation applied to the fixed
internal amplification.
Use the POWER switch, located on the front panel’s, right side to switch the appliance’s power on. The
soft-start function limits against current inrush peaks on the mains, which in addition prevents the mains
line protection switch from activating during power-on. The loudspeaker outputs are activated via relay
switching with a delay of approximately 2 seconds to efficiently attenuate eventual power-on noise. The
PROTECT LED lights during the delay time and the fans run at maximum speed. This is normal, confirm-
ing the immaculate operation of the protection circuitry.