528E
36
Troubleshooting Chapter 10
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?
Is the 528E set for mic-level output?
Is the MIC/LINE switch set correctly?
Hum or buzz in output Check input and output connector wiring (refer to Figure 9-1).
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 OUTPUT display indicating clipping?
Is the input clipping?
Check output loading. Should be above 600 ohms?
Are the power amplifi ers clipping?
Is something else clipping?
Is the 528E set for mic-level output, driving a line-level input,
with the 528E’s gain set fairly high and upstream devices
contributing a sig nifi cant amount of gain?
Noise (hiss) Check input signal levels and level control settings.
The OUTPUT display should indicate signal up to but not
including the CLIP LED.
Check gain settings on upstream equipment.
Is the input signal already noisy?
The system gain structure should be such that the 528E
operates at or near unity.
Is the 528E set for mic-level output, driving a line-level input,
with the 528E’s gain set fairly high and upstream devices
con trib ut ing a sig nifi cant 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?
Do you have the proper input selected?
Is everything downstream really live?
If you are using the patching jacks, unpatch everything
temporarily to see if it is in your patch.
Is the DOWNWARD EXPANDER THRESHOLD set too high?
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