DEVICE
DESCRIPTIONS
PROMATRIX System User Handbook 1.2
5-99
5.6.7 OPERATING PRINCIPLE OF A SPARE SYSTEM
The principle of power amp monitoring and spare device switching is based on the method of pilot tone
surveillance. A 19kHz pilot tone signal is generated, introduced at the power amp’s input and continuously
monitored at the output. The pilot tone signal can either be generated in a DCS 422R module or by an external
source, e.g. directly from the DPM4000. The pilot tone recognition of the DCS 423R module detects the signal at
the output of the corresponding channel and signals “channel o.k.” “channel defect”. If a power amp channel
drops out of operation it has to be replaced by the specially assigned spare amp channel, which in turn results in
the following different constellations for a single spare system:
S
All power amp channels o.k.
No power amp channel has to be replaced by a spare amp channel, so that DCS 423R relays and DCS
422R audio signal switching is not activated either. All corresponding LEDs and amplifier fault contacts
stay inactive.
As long as the system is in this state, the "active LED" on the front panel and the green LED on the rear of
the DCS421 control module are lit. The CFS fault contact is inactive (closed contact).
S
One standard power amp channel fails to operate
Through switching the corresponding DCS423 relay the affected amp channel is replaced by the spare
amp channel. Simultaneously, the corresponding LED and amp fault contact are active. In case of a multi-
channel configuration the DCS422R module additionally switches the audio signal. With single-channel
configurations, the audio signal is not switched. The DCS422 module provides no function, if the pilot tone
signal is externally generated.
As long as the system is in this state, the "active LED" on the front panel and the green LED on the rear of
the DCS421 control module are slowly flashing (2 sec. period). The CFS fault contact stays inactive
(closed contact).
S
The spare amp channel itself fails to operate
No Power amp channel is being replaced by a spare amp channel. Despite the fact that DCS 423R relays
and DCS 422R audio signal switching are not activated, the spare amp fault contact is activated and the
corresponding LED lights.
This state is indicated by a slowly (2 sec. period) flashing "active LED" on the front panel and green LED
on the rear of the DCS421 control module. The CFS fault contact stays inactive (closed contact).
S
Multiple standard power amp channels fail to operate
Only the amplifier channel with the highest priority setting is switched over to the spare amp. In fact, this is
the channel with the lowest position number, counted from the DCS 421R control module. Only the
affected DCS 423R relay is switched, while at the same time, the corresponding LED lights and the
equivalent fault contact is being activated. In case of a multi-channel configuration the DCS422R module
additionally switches the corresponding audio signal. With single-channel configurations, the audio signal
is not switched. The DCS422 module provides no function, if the pilot tone signal is externally generated.
This state is indicated by the quick flashing (1/2 sec. period) of the "active LED" on the front panel and the
green LED on the rear of the DCS421 control module. The CFS fault contact is active (open contact).
S
One or more standard power amp channels and the spare amp channel fail to operate
Power amplifier replacement does not take place. The spare amp fault contact is activated and the
corresponding LED lights even though DCS 423R relays and DCS 422R audio signal switching are not
activated.
This state is indicated by the quick flashing (1/2 sec. period) of the "active LED" on the front panel and the
green LED on the rear of the DCS421 control module. The CFS fault contact is active (open contact).
Note:
The "active LED" on the front panel and the green LED on the rear of the DCS421 control module always indicate
the worst error status of the up to eight spare systems; i.e. the LEDs light permanently as long as all logic spare
systems function without problem. The LEDs flash slowly (2 sec. period), when a single power amplifier fails. They
flash quickly (1/2 sec. period) on the occurrence of an unrectifiable error. If the LEDs do not light at all, either the
control module is defective or you are in the middle of a total power loss.
Note: If a logic spare system is composed of several cascaded DCS 423R modules (proportion greater than 4/1), only
the CFS-contact, the spare amp fault contact and LEDs of the first module are active. CFS-contacts and spare amp
fault contacts of the other modules remain inactive.
When in inactive status (o.k. status), all power amp fault contacts and spare amp fault contacts are open. They are
connected to ground potential in active status (on the occurrence of a power amplifier malfunction). These fault contacts
are used for transmitting “rectifiable power amp fault” conditions to external devices.
Opposed to that, the CFS-contact is connected to ground potential (spare system o.k.) when in inactive state, while it is
open on the occurrence of a “spare system fault”. As a result, an error status will also be signaled during total system
power loss, which satisfies the rules of fail-safety.
Summary of Contents for PROMATRIX System
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