10
Troubleshooting
Symptom
Possible cause
Solution
General malfunction
-
Check the system with the start-up
procedure. See page 10.
Power LED is off
Power supply not connected
Power supply faulty
Check the power connection
Replace with approved power supply
Input and output LEDs
flash on and off
System Diagnostics turned on
Turn off the System Diagnostics
Output current LEDs are
off, input LEDs are on
Loop current turned down
Adjust Loop current
Output and input LEDs
are off, power LED is on
No input signal
Input signal set too low
Check if input signal is present
Adjust the input signal level
Audio quality is poor,
peak LED indicates
Loop cable malfunction
Loop impedance is too high
Loop current set too high
Parametric MLC set too high
Re-run startup procedure. (page 10)
Change the loop cable: use twin cores in
parallel or use a cable with higher cross-
section
Adjust loop curremt
Adjust the Parametric MLC
Audio quality is poor,
peak LED is off, sound
quality using headphone
monitor is also poor
Input signal set too high
Audio source is of poor quality
Reduce input signal level and check
Line/Mic level setting
Change/adjust audio source
Metal Loss Correction frequency setting
The degree of compensation for metal loss is adjusted with the
MLC potentiometer
(3)
.
The start/break frequency is set with the
Parametric MLC knee point switch
(4)
marked:
100Hz, 500Hz, 1kHz, 2kHz.
1. Start with the break frequency set to 2kHz.
2. Adjust the level to -12dB. If this is not sufficient, move to the next lower frequency and
repeat as required.
3. Verify that the loop driver’s voltage doesn’t saturate, i.e. that the peak indicator
(8)
only
flickers temporarily.