Question

Difficulty: MediumSafety Procedures and Environmental Controls

A field technician is assigned to replace an auxiliary cooling fan inside a workstation chassis that integrates both a CRT display assembly and an internal uninterruptible power supply (UPS) unit. To ensure personal safety and prevent electrostatic discharge (ESD) damage to sensitive circuit components during this maintenance procedure, which of the following safety protocols should the technician follow? (Select TWO).

  1. Disconnect all power sources and allow high-voltage capacitors in the CRT and UPS assemblies to fully discharge before servicing internal components.Answer
  2. Attach an ESD wrist strap containing a current-limiting resistor to an unpainted metal surface of the chassis when handling sensitive internal logic boards.Answer
  3. C
    Attach an ESD wrist strap lead directly to the high-voltage anode clip of the CRT monitor to bleed off residual electrostatic charge rapidly.
  4. D
    Remove the safety resistor from the ESD wrist strap ground lead to accelerate electrostatic discharge to the electrical ground.

Answer

The technician must disconnect power sources and allow high-voltage capacitors in CRT and UPS units to discharge, and attach an ESD wrist strap with a safety resistor to an unpainted chassis ground when handling internal logic boards.
High-voltage assemblies like CRT displays and UPS power supplies hold stored capacitor charges even after power disconnection, requiring full discharge before servicing. Additionally, using an ESD wrist strap fitted with a protective resistor connected to an unpainted metallic ground safely equalizes static potential to prevent component damage.

Step-by-Step Solution

1
Identify high-voltage electrical hazards prior to opening the system chassis.
Recognized that CRT display components and UPS power systems contain capacitors capable of storing high voltages after power disconnection.
Capacitor discharge safety precautions prevent severe electrical shock or electrocution.
2
Apply proper electrostatic discharge (ESD) protection protocols for sensitive electronic assemblies.
Utilized an ESD wrist strap with a built-in current-limiting resistor attached to an unpainted chassis ground connection.
Grounding through a safety resistor equalizes electrical potential between the technician and the hardware while protecting against electrical shock.

Key Concept

High-Voltage Equipment and ESD Safety Protocols
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