GROUND Lift Switch
The ground lift switch helps is a perfect means for eliminating possible ground noise loops. In case the power amplifier is operated together with other equipment inside of a rack shelf system, the switch should be set to its GROUNDED position. When using the power amplifier together with other equipment that operates on different ground potentials, the switch should be set to UNGROUNDED.
Power On And Remote Control
When the power amplifier is operated via power remote start (standard operation) an external 24 V power source has to be connected to the POWER REMOTE terminal strip and the mains switch has to be set to its OFF-posi- tion. When correctly connected and with a present supply voltage, the power amplifier is operational. The fans run for approximately 2 seconds and the POWER ON-LED on the front panel lights. The mains switch POWER on the rear of the appliance bridges the mains relay. It is meant for service purposes only. This allows to operate the power amplifier without the presence of an external 24 V power source. The current consumption at the POWER REMOTE input is approximately 25 mA.
Limit Indicator
The indicator lights whenever the integrated limiter is activated. While short blinking means no problem, the continuously lit LED indicates that the volume level needs to be reduced to prevent the connected loudspeaker systems from being damaged by overload.
The audio limiters are capable of controlling overdrive levels of up to 20 dB. Most other power amplifiers without integrated limiters begin to clip, genera- ting nasty distortion that not only attacks your ears but also lead to damaging the connected loudspeaker systems by overload. The limiters are activated only in case of the occurrence of non-linear conditions within the power amplifier; e. g. signal clipping at the operation voltage limit. The limiters do not affect the power amplifier’s overall dynamic range.
Signal Indicator
This indicator is lit when the audio signal exceeds –30 dB. In case short-cir- cuits resulting from broken loudspeaker cables are detected or one of the power amplifier’s protection circuits is activated, the signal indicator is dimmed.
PROTECT
The PROTECT-LED lights whenever one of the power amplifier’s protection circuits – thermal overload, RF, DC, Back-EMF – is activated. In PROTECT mode all loudspeaker lines and output transformers are disconnected via relays and the power amplifier’s audio inputs are short-circuited to prevent the connected loudspeaker systems from being damaged. When the power amplifier enters the PROTECT mode please examine first whether the appliance is overheated. If this is the case, the front and rear ventilation louvres are possibly covered, the nominal load impedance has fallen below the specified minimum value, or a short-circuit occurred at the power output.
When switching the power amplifier on, the PROTECT-LED lights for appro- ximately 2 seconds. This is normal. It signals that the protection circuitry is in working order.
Power ON Indicator
This LED lights when the power amplifier is connected to the mains and its power switch is set to the ON-position. If the indicator does not light although the power amplifier is switched on, the appliance is not connected to the mains or the primary fuse is blown.
