Computer Monitor Repair

Computers are useless without monitors. This Fix-It Guide on computer monitor repair tells how a flat-screen or tube-type computer monitor works, what often goes wrong, how to identify a computer monitor problem, and what parts and tools you will need to fix it. The tips in this Fix-It Guide apply to both flat-screen and older tube-type computer monitors. It includes step-by-step instructions for how to test and replace a monitor fuse. This guide also refers you to electrical receptacle repair, electrical cord repair, and computer repair when appropriate.

Flat-screen computer monitors have miniature circuit boards that should not be repaired except by electronic technicians. Older CRT computer monitors with analog VGA data cable often have replaceable fuses, the first thing to go out.

Flat-screen computer monitors have miniature circuit boards that should not be repaired except by electronic technicians. Older CRT computer monitors with analog VGA data cable often have replaceable fuses, the first thing to go out.

How Does a Computer Monitor Work?

A computer monitor, sister to the tube-type television monitor, displays information from a computer on a screen. The monitor uses digital values sent by a computer processor to create a stream of electrons that light up phosphors on the inside of the screen. The signals are in each of the three primary colors, combined into various color signals that seem to move across the screen. Portable computers use a screen made up of liquid crystal display (LCD) cells instead of phosphors. Computer monitors receive their signal from a monitor cable from the computer and their power from a separate electrical cord.

Flat screen or flat panel monitors are connected to computers and other devices using Display Port (DP), Digital Video Interface (DVI), High-Definition Multimedia Interface (HDMI), or older-style analog Video Graphics Array (VGA) data connections.

What Can Go Wrong with a Computer Monitor?

Computer monitor problems are not always problems with the monitor. Testing of the monitor must be done with the computer. The monitor image may not display. The image on the screen may not be clear and bright.

How Can I Identify a Computer Monitor Problem?

  • If a computer monitor does not come on, make sure there is power to the electrical receptacle. Check the electrical cord. Check the connections between the monitor and the computer  and make sure the computer is on. Test the line fuse (see below). Also replace the data cord (DP, DVI, HDMI, VGA; see above).
Computer Monitor Repair

Interior of an older CRT computer monitor. Identify but don’t touch the power supply.

  • If the image on the computer monitor screen is not clear and bright, check your owner’s manual for instructions on adjusting the monitor. Typically there are adjustment buttons on the monitor face below the screen.

What Do I Need for Computer Monitor Repair?

Replacement cables and fuses are available from the manufacturer as well as from local computer shops. Tools you may need to access, test, and fix a computer monitor include these:

  • Screwdrivers
  • Multimeter

What Are the Steps to Computer Monitor Repair?

Fix-It Tip

A computer monitor gets its instructions from a video controller card in the computer. The card may be an add-on expansion card or it may be built into the main circuit board, called the motherboard. If it is a separate card, you may need to open the computer and make sure the card is firmly connected. Also check the flat data cable that runs between the video card and the motherboard, if so equipped.

Computer Monitor Repair

Locate, remove, and test the line fuse, typically located near the power cord entry.

Test and replace a computer monitor fuse:

  1. Disconnect the computer monitor from the electrical receptacle and from the computer processor.
  2. Lay the monitor on a padded surface and remove the housing screws (some may be under pop-out tabs).
  3. Slide the rear housing off.
  4. Locate the line fuse typically near the power cord entrance. Remove the fuse from its holder and test it with a multimeter. Replace the fuse if it is faulty.

Caution!

For safety, follow the manufacturer’s instructions in the owner’s manual to discharge the video tube before working near it. In most cases this means using jumper wires to connect a 10,000-ohm resistor between the chassis ground or common ground and a screwdriver, and shorting the high-voltage lead by inserting the screwdriver under the suction cup.

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