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Subel. F
6 questions
Subelement F

Installation, Maintenance & Repair

Section 50

Safety

Choose the most correct statement with respect to component damage from electrostatic discharge:

  • ESD damage occurs primarily in passive components which are easily identified and replaced.
  • ESD damage occurs primarily in active components which are easily identified and replaced.
  • The technician will feel a small static shock and recognize that ESD damage has occurred to the circuit.
  • Correct Answer
    ESD damage may cause immediate circuit failures, but may also cause failures much later at times when the RADAR set is critically needed.

ESD - Electro-Static Damage may damage internal components in a manner that is not immediately evident causing equipment to fail at a later date, thus Answer D. is the right one.

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Before testing a RADAR transmitter, it would be a good idea to:

  • Make sure no one is on the deck.
  • Make sure the magnetron's magnetic field is far away from the magnetron.
  • Correct Answer
    Make sure there are no explosives or flammable cargo being loaded.
  • Make sure the Coast Guard has been notified.

RADAR transmitted RF power may cause ship-to-shore electrostatic discharges that could ignite flammable cargo or detonate explosives being loaded or off-loaded from the ship, so Answer C. is the right one.

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While making repairs or adjustments to RADAR units:

  • Wear fire-retardant clothing.
  • Correct Answer
    Discharge all high-voltage capacitors to ground.
  • Maintain the filament voltage.
  • Reduce the magnetron voltage.

Un-discharged high-voltage capacitors have killed technicians doing repair work in a transmitter or it's associated power supply.

Always make sure high-voltage capacitors are discharged before opening, so Answer B. is the right one.

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While removing a CRT from its operating casing, it is a good idea to:

  • Discharge the first anode.
  • Test the second anode with your fingertip.
  • Correct Answer
    Wear gloves and goggles.
  • Set it down on a hard surface.

A CRT is a sizable vacuum vessel made out of glass that can injure people nearby if the CRT is dropped and it implodes.

Therefore always wear gloves to keep the CRT from slipping out of your hands and goggles to keep flying glass out of your eyes in case the CRT implodes.

Answer C. is the right one.

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If a CRT is dropped:

  • Most likely nothing will happen because they are built with durability in mind.
  • It might go out of calibration.
  • The phosphor might break loose.
  • Correct Answer
    It might implode, causing damage to workers and equipment.

A CRT (Cathode-ray Tube) is a vacuum tube, making it susceptible to break with impact in certain surface areas.

If a CRT (Cathode Ray Tube) is dropped, there is a risk that it might implode, causing damage to workers and equipment.

A CRT is a vacuum tube that contains an electron gun and a phosphorescent screen, used in older display technology such as television sets and computer monitors. The vacuum inside the CRT tube creates a pressure difference between the inside and outside.

If a CRT is dropped or subjected to a severe impact, the fragile glass envelope of the tube can shatter. This sudden breakage can cause the internal vacuum to collapse rapidly. As a result, the implosion of the CRT can occur, leading to a violent inward collapse of the glass, potentially sending sharp fragments flying and creating a hazardous situation.

The implosion of a CRT can pose a danger to workers and equipment in the vicinity. Sharp glass shards and debris can cause injuries, and the collapsing glass may damage nearby components or devices.

It is crucial to handle CRTs with care and follow appropriate safety protocols to minimize the risk of implosion and associated hazards.

Mnemonic: "Implosion Hazard"

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Prior to removing, servicing or making measurements on any solid state circuit boards from the RADAR set, the operator should ensure that:

  • Correct Answer
    The proper work surfaces and ESD grounding straps are in place to prevent damage to the boards from electrostatic discharge.
  • The waveguide is detached from the antenna to prevent radiation.
  • The magnetic field is present to prevent over-current damage or overheating from occurring in the magnetron.
  • Only non-conductive tools and devices are used.

Solid-state circuit boards from ANY type of equipment are extremely susceptible to instant damage from ESD - Electro-Static Discharges.

Therefore ALWAYS remove static electricity via grounded straps on your wrists before removing the circuit board and ALWAYS place the circuit boards you will work on on a grounded static mat to keep them safe from ESD.

Answer A. is the right answer.

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