CRT Safety Procedure Before discharging a cathode-ray tube (CRT) in a computer display for service, what is the first safety step you should perform?

Introduction / Context:
CRTs operate at high voltages and can retain charge after power-off. Discharging a CRT must follow strict safety steps to avoid shock and equipment damage. This question asks for the very first action before any discharge procedure begins.

Given Data / Assumptions:

• Technician is preparing to service a CRT-based display.
• Standard ESD and electrical safety practices apply.
• Proper discharge tools and PPE are available.

Concept / Approach:

Always remove power before servicing high-voltage equipment. Power the unit down and unplug it from the mains. Only after confirming the unit is de-energized should you proceed to properly discharge the anode using an insulated tool connected to chassis ground via a resistor.

Step-by-Step Solution:

Verification / Alternative check:

Use a voltmeter or follow manufacturer guidelines to confirm residual voltage is dissipated before touching HV areas.

Why Other Options Are Wrong:

Removing parts before ensuring power is off increases hazard. Merely disconnecting video or removing assemblies does not address dangerous HV. Thus, the first step must be powering off and removing the power source.

Common Pitfalls:

Assuming power off is enough without unplugging, or using ad-hoc tools for discharge. Always follow approved procedures and use insulated tools.

Final Answer:

Turn power off before removing power source