Dynacord DPA 4260 Stereo Amplifier User Manual


 
24
GROUND Lift Switch
The ground lift switch helps is a perfect means for eliminating possible
ground noise loops. In case the power amplier 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 amplier 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 amplier is operated via power remote start (standard ope-
ration) 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-positi-
on. When correctly connected and with a present supply voltage, the power
amplier 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 pur-
poses only. This allows to operate the power amplier without the presence
of an external 24 V power source. The current consumption at the POWER
REMOTE input is approximately 25mA.
Limit Indicator
The indicator lights whenever the integrated limiter is activated. While short
blinking means no problem, the continuously lit LED indicates that the vo-
lume level needs to be reduced to prevent the connected loudspeaker sys-
tems from being damaged by overload.
The audio limiters are capable of controlling overdrive levels of up to 20
dB. Most other power ampliers without integrated limiters begin to clip,
generating 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 amplier; e. g. signal clipping at the operation voltage limit. The limit-
ers do not affect the power amplier’s overall dynamic range.
Signal Indicator
This indicator is lit when the audio signal exceeds –30 dB. In case short-
circuits resulting from broken loudspeaker cables are detected or one of
the power amplier’s protection circuits is activated, the signal indicator is
dimmed.
PROTECT
The PROTECT-LED lights whenever one of the power amplier’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 amplier’s audio inputs are short-circuited to prevent
the connected loudspeaker systems from being damaged. When the power
amplier enters the PROTECT mode please examine rst whether the appli-
ance is overheated. If this is the case, the front and rear ventilation louvres
are possibly covered, the nominal load impedance has fallen below the spe-
cied minimum value, or a short-circuit occurred at the power output.
When switching the power amplier 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 amplier is connected to the mains and
its power switch is set to the ON-position. If the indicator does not light alt-
hough the power amplier is switched on, the appliance is not connected to
the mains or the primary fuse is blown.
POWER
GROUNDED
UNGROUNDED
CHASSIS SWITCH
CIRCUIT TO
T
+24V ON
0V OFF
+
POWER REMOTE
SIGNAL
LIMIT
CH A CH B
POWER
PROTECT