CPI Troubleshooting & Fault Diagnosis 2

Question 1

A newly installed HDMI display shows a 'No Signal' error but the source device is powered on. What is the FIRST step to diagnose?

Accepted Answer

Verify the display input source matches the connected port

Answer

Mismatched input source selection is the most common cause of 'No Signal' errors before any hardware is replaced.

Question 2

An amplifier produces a loud 60 Hz hum only when audio cables are connected. What is the most likely cause?

Accepted Answer

A ground loop between components

Answer

A 60 Hz hum introduced when connecting audio cables is the classic symptom of a ground loop caused by differing ground potentials between components.

Question 3

A touchscreen panel is unresponsive in one corner only. After a reboot the issue persists. What should be checked next?

Accepted Answer

Inspect the touchscreen ribbon cable for damage or loose connection

Answer

Localized touch failure that survives a reboot typically points to a physical ribbon cable fault rather than a software issue.

Question 4

A motorized projection screen stops halfway during extension. The motor runs briefly then stops. What is the most probable fault?

Accepted Answer

Thermal overload protection tripping due to mechanical binding

Answer

Thermal cutoff triggering mid-travel indicates the motor is drawing excess current due to mechanical binding or obstruction.

Question 5

After running Cat6 cable through conduit, a network switch port shows an amber link light instead of green. What does this indicate?

Accepted Answer

The port is operating at 10/100 Mbps instead of Gigabit

Answer

On most managed switches, amber link light signals a 10/100 Mbps connection, meaning the cable or NIC cannot negotiate Gigabit speed.

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