CET Power Supply Design & Repair 2

Question 1

Which component in a linear power supply is primarily responsible for reducing AC input voltage before rectification?

Accepted Answer

Power transformer

Answer

Filter capacitor

Answer

Zener diode

Answer

Pass transistor

Question 2

In a switching power supply, what is the primary function of the PWM (Pulse Width Modulation) controller IC?

Accepted Answer

Regulate output voltage by adjusting switch duty cycle

Answer

Rectify the AC input

Answer

Filter output ripple

Answer

Step down transformer turns ratio

Question 3

A technician measures excessive ripple on a power supply output. Which component is most likely failing?

Accepted Answer

Output filter capacitor

Answer

Rectifier diode

Answer

Input fuse

Answer

Voltage reference IC

Question 4

What does the term 'crowbar circuit' refer to in power supply design?

Accepted Answer

An overvoltage protection circuit that shorts the output

Answer

A voltage boosting circuit

Answer

A soft-start inrush limiter

Answer

A bridge rectifier topology

Question 5

In a full-wave bridge rectifier with a 24 V AC RMS input, approximately what is the peak DC voltage before filtering?

Accepted Answer

33.9 V

Answer

24 V

Answer

17 V

Answer

48 V

Question 6

Which topology is most commonly used in ATX computer power supplies due to its efficiency at high power levels?

Accepted Answer

Forward or half-bridge switching converter

Answer

Linear series-pass

Answer

Half-wave rectifier

Answer

Flyback converter

Question 7

A power supply's output voltage is too high and does not respond to the trim pot adjustment. Which section should the technician inspect first?

Accepted Answer

Feedback/error amplifier network

Answer

Input rectifier bridge

Answer

Output filter capacitors

Answer

Inrush current limiter