6
FAULT CONDITION
INDICATION
The MX power amplifier modules have
intelligent loudspeaker protection systems.
If a fault occurs in any power amplifier
channel it will report the nature and location
of the fault using the seven LEDs in the
amplifier’s display window. When a fault
occurs, the normal display showing the
number and location of channels installed
will change as follows.
First the display will show the fault type –
numbered from 1 to 5 – indicated by the
number of blue LEDs illuminated starting
from the leftmost.
n
~~~~~~
Fault type 1
nn
~~~~~
Fault type 2
nnn
~~~~
Fault type 3
nnnn
~~~
Fault type 4
nnnnn
~~
Fault type 5
A blue LED illuminated is shown “
n
”
and
no LED illuminated is shown
“~”.
The above display will appear for about 2
seconds, after which it will change to show
the location of the faulty module. The far
left module (from the front of the amplifier)
is module 1 and the far right is module 7.
With 1 x 150W modules the channel and
module numbers are the same. The
amplifier module number is indicated by
illuminating all LEDs, but only the one
relating to the faulty module location will be
blue “
n
”
, the others will be red “
p
”.
Hence:
npppppp
Module 1 reporting
fault
pnppppp
Module 2 reporting
fault
ppnpppp
Module 3 reporting
fault
pppnppp
Module 4 reporting
fault
ppppnpp
Module 5 reporting
fault
pppppnp
Module 6 reporting
fault
ppppppn
Module 7 reporting
fault
This display will appear for about 2
seconds, after which it will alternate with
the “Fault type” display. The displays will
continue to alternate while the fault
persists, or until the unit is switched off or
into standby.
With 2x80W modules, the upper amplifier
channel in each module has the same
number as the module (1 to 7), but the
lower amplifier has that number plus 7, so
the lower amplifier channels run from 8 to
14 (8 being the lower channel of the far left
module). If a fault occurs in one of channel
numbers 8 to 14 it is indicated by lighting
the far right LED blue in the “Fault type”
display, thus a fault type 2 (short-circuit) in
channel 12 (the lower channel of module 5)
is indicated by displaying:
nn
~~~~
n
Fault type 2 in lower
channel alternating with
ppppnpp
Module 5 reporting
fault
The table below indicates what action
should be taken when a fault is reported.
“Overheat” and “Short-circuit” faults can
usually be cured by checking your amplifier
setup. The other faults indicate a failure
within the amplifier so the unit must be
returned for service.
Fault Type
Description of Fault
Action required
1
“Overheat”
Amplifier channel has overheated
Make sure that ventilation grilles in amplifier’s top cover and bottom chassis are not obstructed.
Allow amplifier channel to cool - typically 10 - 20 minutes depending upon the room temperature
and ventilation - after which the channel’s loudspeaker will be re-connected. The amplifier will
cool more quickly if switched to standby. When the loudspeaker is re-connected, make sure
that the volume is not set too high – i.e. that the sound is clean and undistorted. If the sound is
distorted on loud passages, reduce the volume setting. If the problem persists return unit to
approved Service Agent.
2
“Short-circuit”
Loudspeaker wiring short-circuited,
or very low impedance loudspeaker
connected, or too many loudspeakers
wired in parallel to one amplifier
channel
Switch amplifier POWER off at rear.
Check that load on each channel is no less than 4
Ω
(one 4
Ω
speaker or two 8
Ω
speakers to
each channel).
Check loudspeaker wiring – at both amplifier and speaker ends.
Make sure there are no small strands of wire that might be causing a short circuit.
Re-wire if necessary.
If the problem persists return unit to approved Service Agent.
3
Excessive positive DC output
Return unit to approved Service Agent.
4
Excessive negative DC output
Return unit to approved Service Agent.
5
AC power failure to power amplifier
channel
Return unit to approved Service Agent.
