Fans And Cooling System - Meyer Sound MILO Operating Instructions Manual

CHAPTER 2
NOTE:
The limit LEDs indicate when the safe
power level is exceeded. If any channel on an
entire system of MILO loudspeakers begins to limit
before reaching the required sound pressure level
(SPL), consider adding more loudspeakers to satisfy
the SPL requirements without exposing the drivers
on that channel to excessive heat and/or excursion.

FANS AND COOLING SYSTEM

MILO uses a forced-air cooling system with four fans to
prevent the amplifier modules from overheating. The fans
draw air in through ducts on the front of the cabinet, over
the heatsinks, and out the rear of the cabinet. Because dust
does not accumulate in the amplifier circuitry, its lifespan is
increased significantly. The front grille surface acts as an air
filter for the cooling system and should always be in place
during operation (Figure 2.5).
Figure 2.5: Airflow through MILO
Because the grille acts as a filter, it should be inspected and
cleaned routinely – once every six months, or once every
three months in a dusty environment – to assure proper
airflow and cooling. The grille can be vacuumed to remove
dust.
TIP: If your MILO loudspeaker is weather-
protected, the grille must be removed in
order to the clean the additional foam underneath
the grille, which covers the air inlets.
CAUTION: When operating a weather-
!
protected MILO loudspeaker be sure the
rain hood is fully open. Leaving the hood closed
or partially open will limit the airflow through the
amplifier, which could cause it to overheat and shut
down.
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Two variable-speed primary fans run continuously and
inaudibly at their slowest speed. The primary fans increase
speed when either of the two heatsinks reaches 42˚ C. The
fans reach full speed at 62˚ C and are still barely audible
even near the cabinet, and without an audio signal. In the
unusual event that the heatsink temperature reaches 74˚ C,
the secondary fans turn on and are clearly audible without
an audio signal. The secondary fans turn on in response to:
 Primary fan failure (check status immediately)
 High source levels for a prolonged period
 Accumulation of dust along the cooling path
The secondary fans turn off when the temperature
decreases to 68˚ C.
NOTE: In the highly unlikely event that the
secondary fans do not keep the temperature
below 85˚ C, the MILO loudspeaker automatically
shuts down until AC power is removed and
reapplied. If the MILO loudspeaker shuts down
again after cooling and reapplying AC power,
contact Meyer Sound for repair information.
Despite MILO's filtering, extensive use or a dusty operating
environment can allow dust to accumulate along the path
of the airflow, preventing normal cooling. To avoid this, you
should periodically remove the grille frame and amplifier
module and use compressed air to clear dust from the grille,
fans and heatsinks. Make sure that the air ducts are clear.
TIP:
For weather-protected MILO
loudspeakers, the foam covering the horns
should also be cleaned with compresed air.
CAUTION:
Be sure to unplug power to the
!
unit before cleaning the amplifier.