How to Know That Your LCD Capacitors Are Bad

Written by skip shelton Google
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How to Know That Your LCD Capacitors Are Bad
Capacitors store electricity after you remove the power cable from a device. (Hemera Technologies/PhotoObjects.net/Getty Images)

LCD capacitors store electricity. The electrical storage allows higher capacity voltage discharges than the incoming electrical line can provide. Inside a capacitor, an insulator separates two plates. Damaged insulators or plates compromise the LCD capacitor's functionality. Failed capacitors may leak insulating fluid, create an electrical short, fail to store a charge, or leak charges over time. Test the LCD capacitors to determine if the capacitor is functional.

Skill level:
Moderate

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Things you need

  • Soft towel
  • Screwdriver
  • Heavy gauge copper wire
  • Wire strippers
  • Electrical tape
  • Multimeter

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Instructions

    Preparation and Capacitor Discharge

  1. 1

    Turn off the LCD TV or monitor and pull the electrical plug from the socket.

  2. 2

    Lay the LCD facedown on a soft towel over a flat surface to protect the screen during maintenance.

  3. 3

    Remove the screws holding the back cover in place with a screwdriver. Remove the back cover of the LCD to access the electrical components.

  4. 4

    Locate the capacitors on the electrical board. Capacitors have two leads or prongs leading from them to the board. Capacitor leads extend either vertically from the bottom of the capacitor or horizontally from both ends of the capacitor.

  5. 5

    Strip away one to two inches of insulation from a heavy gauge copper wire with wire strippers. If your wire is already fully bare, wrap a portion of the wire with electrical tape to create an insulated handle.

  6. 6

    Grasp the insulated portion of the thick copper wire. Connect the bare portion of the copper wire to both leads extending from the capacitors you want to test. If necessary, bend the wire to enable full contact with the capacitor leads. This will discharge the energy stored in the capacitors before you test them. Do not touch the bare portion of the wire during contact with the capacitor.

  7. 7

    Maintain wire pressure against the leads for a full 30 seconds. The wire connecting both leads allows the stored electricity to travel freely from the plates. The thick wire acts as a resistor to drain the plates of stored electricity. If the wire becomes hot during discharge, remove the wire and allow it to cool. Repeat the discharge process until you are able to maintain a full 30 seconds.

    Testing

  1. 1

    Turn on the multimeter and adjust it to measure resistance, or "Ohms." The Ohm symbol looks like the Greek letter Omega.

  2. 2

    Press the black multimeter lead to one of the leads protruding from the capacitor. Press the red multimeter lead to the other capacitor lead.

  3. 3

    Monitor the Ohms resistance on the multimeter.

  4. 4

    Examine the multimeter readings to determine the failure type, if any is present. Capacitors in an "open" state will not show any reading on the multimeter when you connect the leads. Leaking capacitors will initially have a "zero" reading, will climb slowly toward infinity and then will stop climbing before reaching infinity. Fully functional capacitors will initially show a "zero" reading and will slowly climb to infinity. The climbing resistance is a result of the multimeter battery slowly charging the capacitor through the connected leads.

  5. 5

    Examine the capacitors for unexpected bulges or leaks. Bulges and leaks indicate internal failure.

  6. 6

    Replace any capacitors failing the Ohm measurement test and any capacitors that are bulging or leaking.

Tips and warnings

  • Avoid accidental damage to the LCD and personal injury by discharging the electricity stored in the capacitor before testing. Avoid touching the uninsulated part of the copper wire when connected to the capacitor leads.
  • Discharge the capacitor between each multimeter test to prevent accidental discharge and to ensure accurate measures.

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