CAT Problem Solving and Troubleshooting 2

Question 1

A powered loudspeaker produces a loud 60 Hz hum even when no signal is connected. What is the most likely cause?

Accepted Answer

Ground loop through the AC power connection

Answer

Faulty amplifier output transistor

Answer

Blown high-frequency driver

Answer

Incorrect crossover frequency setting

Question 2

During a live event, one side of a stereo mix drops to silence intermittently. The mixing console meters show signal on both channels. Where should you check first?

Accepted Answer

The cable run between the console and the amplifier

Answer

The FOH EQ settings

Answer

The stage monitor mix

Answer

The microphone capsule

Question 3

An amplifier's clip indicator lights continuously at moderate gain settings with a clean input signal. What is the most probable cause?

Accepted Answer

The input sensitivity is set too high

Answer

The output impedance is too low

Answer

The power supply voltage is too high

Answer

The signal frequency is too low

Question 4

You measure 0 VDC on the output of a Class-D amplifier while the input signal is present and the power LED is on. What is the best next diagnostic step?

Accepted Answer

Check the protection relay and fault indicator

Answer

Replace the output capacitors immediately

Answer

Increase the input gain

Answer

Swap the speaker cables

Question 5

A condenser microphone produces distorted audio only at high sound pressure levels. The most likely fault is:

Accepted Answer

Overloaded mic preamplifier input

Answer

Insufficient phantom power voltage

Answer

Defective XLR connector shell

Answer

Wrong polar pattern selected

Question 6

A DSP processor shows signal on its input meters but the output meters read nothing. Outputs have been verified with a different device. What should you check?

Accepted Answer

The output routing matrix inside the DSP

Answer

The input sample rate setting

Answer

The microphone phantom power supply

Answer

The amplifier gain structure

Question 7

Feedback occurs in a system only when the presenter stands near the front fill speakers. The most effective corrective action is:

Accepted Answer

Lower the front fill gain or apply a narrow notch EQ at the feedback frequency

Answer

Reduce the main PA level by 6 dB

Answer

Switch the microphone to omnidirectional pattern

Answer

Increase the subwoofer output