TROUBLESHOOTING
Ear symbol not illuminated
• Check that the power switch is toggled to the ON (I) position.
• Check fuse continuity. A 20mm fuse is incorporated into the AC POWER inlet. It is necessary
to remove the power cord before extracting the fuse holder. Test the continuity of the fuse
using a multimeter. A spare fuse is provided in the fuse holder.
Any replacement fuse MUST be of the same rating and type as printed on the rear of
the unit.
Ear symbol flashing continuously
Amplifier has failed self test and is in safe mode. Signal will not be fed into one or both loops.
Switch the unit off, remove all connections except the loop and power connections, turn all front
panel controls to minimum and switch back on. If the problem persists, contact Ampetronic for
advice.
COMPRESSION LEDs not illuminating
Check input connections.
Ensure that the appropriate front panel control (INPUT1 or INPUT2) is turned up. Check there is
sufficient signal level for the required input.
CURRENT LEDs not illuminating
There are many possible causes for this:
• Check the COMPRESSION LEDs are illuminating.
• Check that the CURRENT controls are turned up sufficiently.
• Check the LOOP, or TEMP LEDs are not illuminated.
• Ensure the Ear symbol is illuminated and not flashing.
• Check that the loop cables are connected, terminated correctly and inserted into the LOOP
OUTPUT sockets.
• Check the loops are not open circuit, short circuit, or connected to earth (see instability or high
frequency noise section of Troubleshooting)
• Switch the unit off and turn back on.
Note: You can listen to the actual loop signal by using a pair of headphones plugged into the
monitor socket. Channel A = left, channel B = right
.
CLIP LED
(
s
)
illuminated
Indicates that the output voltage is clipping. Occasional lighting of this indicator is normal on peaks
of signal.
• Turn down the CURRENT control on the channel(s) in question to avoid causing the output
voltage to clip.
• Check the loop is not open circuit, short circuit, or connected to earth (see instability or high
frequency noise section of Troubleshooting)
• Check the loop is within specified limits.
TEMP LED illuminated
Indicates that the internal heatsink is too hot. Loop current is not delivered to either channel.
• Ensure that the unit is installed in a location with sufficient ventilation
Ampetronic MLD5 Installation Handbook
Page 8
