Lab.gruppen PLM 20K44 Operation Manual page 22

5. Operation and performance
5.3.8.2. Power Output Channels
A power output channel temperature warning or fault is indicated in one of the front panels LEDs (in the right-hand
soft function buttons).
• A warning is indicated by a static yellow LED and adjacent warning message: TEMP WARN:CH
• A fault is indicated with a static red LED and adjacent warning message: TEMP FLT:CH
An event report is sent to the Lake Controller software for both the warning and the fault. If a temperature fault
condition arises on a power channel, the output of that channel will be muted.
5.3.8.3. Power Supply / DSP
A power supply (PSU) or DSP temperature warning or fault is indicated by the LEDs in the four left function buttons
being lit at the same time.
• A warning is indicated by static yellow LEDs and adjacent warning message: TEMP WARN:PSU
(or TEMP WARN:DSP)
• A fault is indicated with static red LEDs and adjacent warning message: TEMP FLT:PSU (or TEMP FLT:DSP)
At temperatures above the critical warning level and below the dangerous fault level, the ISVPL threshold is slowly
reduced to decrease the output power and cool down the device. This enables the device to continue to pass
audio, although with a reduced amplitude, in extreme conditions. If reducing the ISVPL threshold does not cool
down the device a temp fault will still be issued when the dangerous temperature level is reached. An event report
will be sent to the Lake Controller software for both the warning and the fault.
5.3.9. DC Protection
DC protection is implemented on each power output to prevent damage to connected loudspeakers or any
PLM+ components. DC present at the output will cause the PLM+'s power output module breaker to blow. In this
instance a red LED will illuminate and NEEDS SERVICE will display on the LCD.
Note: The power output channel modules are independent of the input voltage. This is not a user-
servicable fault condition and the unit should be returned for repair.
5.3.10. VHF Protection
The PLM+ includes protection circuits that detect Very High Frequency (VHF) content in the input signal. The
detection is frequency-dependent, initiated from 10 kHz upwards. If continuous VHF signals are detected above
the threshold, the output will mute for approximately 6 seconds before a further measurement is taken. When
continuous VHF signal stops, the output unmutes and the amplifier returns to normal operation.
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PLM+ SERIES Operation Manual rev 1.0.0