527E
13
Troubleshooting
Troubleshooting Chart
SYMPTOM
PROBABLE CAUSE
No output
Check cables and connections.
Are inputs driven by outputs, and outputs driving inputs?
Verify cables, source and load by patching input and output
connections together at the unit.
Check for AC power presence. Power LED on?
Check output by plugging headphones into output connector
(use an adapter).
Are the LED displays operating?
Did you use the correct output (mic or line-level)?
Is the M
IX
C
ONTROL
set correctly?
Hum or buzz in output
Check input and output connector wiring.
Ground loop. Check related system equipment grounding. Are
all system components on the same AC ground?
Distortion
Check input signal. Is it too hot, or is it already distorted?
Is the O
UTPUT
display indicating clipping ?
Is the input clipping?
Check output loading. Should be above 600 ohms.
Are the power amplifiers clipping?
Is something else clipping?
Noise (hiss)
Check input signal levels and level control settings.
The O
UTPUT
display should indicate signal up to but not
including the C
LIP
LED.
Check gain settings on upstream equipment.
Is the input signal already noisy?
The system gain structure should be such that the 527E
operates at or near unity.
Is the 527E set for mic-level output, driving a line-level input,
with the 527E’s gain set fairly high and upstream devices
contributing a significant amount of gain?
No LED displays
Is the unit plugged in and turned on?
Is the AC outlet OK?
No nothing
If you are using a condenser microphone, is the phantom
power switched on?
Did you connect to the proper input and output?
Is everything downstream really live?
Is the D
OWNWARD
E
XPANDER
T
HRESHOLD
set too high?
Chapter 8