ISCET Test Equipment Operation & Troubleshooting 2

Question 1

When using an oscilloscope to measure a signal, the waveform appears distorted and noisy. What is the MOST likely first corrective action?

Accepted Answer

Adjust the trigger level and source

Answer

Improper trigger settings are the most common cause of an unstable or distorted waveform display on an oscilloscope.

Question 2

A frequency counter displays an erratic reading when measuring a low-frequency signal. What is the most probable cause?

Accepted Answer

The gate time is set too short

Answer

A gate time that is too short provides insufficient sample time for accurate low-frequency measurements, resulting in erratic readings.

Question 3

Which oscilloscope control is used to shift the waveform vertically without changing the amplitude scale?

Accepted Answer

Position (vertical)

Answer

The vertical position control moves the waveform up or down on the display without altering the amplitude scale.

Question 4

A technician measures 12 VDC with a DMM, but the circuit is not functioning. The NEXT best diagnostic step is to:

Accepted Answer

Check for voltage drop across series components under load

Answer

Measuring voltage drop under load reveals resistive losses or failed components that are not apparent from an open-circuit voltage reading.

Question 5

What does a 'leading edge' trigger on an oscilloscope mean?

Accepted Answer

The scope triggers on the rising edge of the waveform

Answer

A leading (positive or rising) edge trigger causes the oscilloscope to begin its sweep when the signal transitions from low to high.

(ISCET) International Society of Certified Electronics Technicians Practice Test