A1 front panel
OFF
ON
REM
PWR
TEMP
REM
PROT
LOCK
LO
HI
(4.0 E)
2-5
2.2.
A1 controls & indicators
PWR - Power (green)
−
On
. when the mainframe is connected to the mains supply, swit-
ched on and ready for use.
−
Off
. The mainframe is not connected to or powered from the
mains supply. The mains overvoltage protection has triggered
(see above) or the mainframe is not switched on.
−
Flashes
during the initial power-up cycle for about 2 seconds
and also when the mains overvoltage protection circuit is trigge-
red by an external fault (see also PROT below).
TEMP - Temperature (red)
−
Flashes
. The mainframe has switched off because the maximum
permissable operating temperature has been exceeded. This oc-
curs if the power amplifier heatsink temperature exceeds 83° C or
if the mains power transformer temperature exceeds 120° C.
PROT - Protect (red)
As the two mainframe power amplifier channels operate indepen-
dently there are separate PROT indicators for LO and HI channel.
−
On
. An internal fault has been detected on the mainframe chan-
nel concerned and that channel has been disconnected (e.g. DC
voltage fault in the output stage).
−
On and the PWR LED also flashes
. An external fault has
switched off the affected power amplifier channel. Typical faults
producing this indication are shorted speaker cables or a load
impedance which is too low for the amplifier to drive. Once the
cause of the fault has been identified and removed, either muting
and un-muting the controller module, or powering the mainframe
off and on again, will reset the mainframe fault protection circuits
and allow normal operation to resume.
REM - Remote (green)
−
On
. The mainframe is connected to the d&b RIB and ready for
communication.
LOCK (yellow)
−
On
. The mainframe has been placed in a locked condition by a
remote control system. This means that all the mainframe and
controller module controls with the exception of the mains switch
are inactive (locked out).
−
Off
. The A1 mainframe is set to local operation, i.e. may be ope-
rated using the front panel controls.
OFF/REM/ON (power switch)
−
OFF
. With the exception of the mains overvoltage protection cir-
cuit, the mainframe is isolated from the mains supply.
−
REM
. The mainframe is set to remote operation. If no remote
control system is connected this setting is equivalent to the power
switch OFF position.
−
ON
. The mainframe is switched on. In this switch position, the re-
mote control system can monitor and display the operational sta-
tus of the mainframe but cannot change any settings.
