Monitor safety — Is a standard handheld multimeter suitable for measuring a CRT monitor’s high-voltage output?

Difficulty: Easy

Correct Answer: False

Explanation:


Introduction / Context:
Legacy CRT displays use very high voltages (often 15–30 kV) for electron beam acceleration. Measuring these requires specialized high-voltage probes and strict safety protocols.



Given Data / Assumptions:

  • We are considering a typical handheld DMM without an external HV probe.
  • CRT anode voltages greatly exceed normal DMM ratings.
  • Technician safety is a priority.


Concept / Approach:

Standard multimeters are rated for much lower voltages and specific measurement categories. Directly connecting them to a CRT high-voltage node can destroy the meter, arc internally, and seriously injure the user. Proper high-voltage probes scale the voltage and add insulation barriers.



Step-by-Step Solution:

Identify CRT anode voltage level: tens of kilovolts.Compare to DMM rating: typically up to 600–1000 V CAT-rated.Conclude: a standard DMM is not suitable; use an appropriate HV probe or dedicated HV meter.Follow safe discharge and one-hand techniques when servicing.


Verification / Alternative check:

Meter manuals list maximum input and safety category ratings. CRT service literature mandates HV probes and isolation practices.



Why Other Options Are Wrong:

Selecting AC mode, unplugging, or auto-range does not change the voltage rating or insulation integrity of the instrument. “True” is unsafe and incorrect.



Common Pitfalls:

Attempting to probe the anode cap directly, ignoring stored charge, and failing to use a bleeder resistor for discharge.



Final Answer:

False.

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