How to Check a VGA Cable With a Multimeter
VGA cables that ship with brand-name monitors or those made by well-known cable manufacturers seldom fail. Additionally, better VGA cables usually support newer 16:9 aspect ratios and resolutions far beyond the 1,024 x 768 standard of older CRT monitors. However, damaged or low-quality VGA cables may not support higher resolutions – or work at all – if solder or wiring between pin connectors lacks continuity. Some lower-end VGA cables do not use all the connectors' pins in an attempt to save on manufacturing costs. To determine if a VGA cable has continuity on all pins, use a multimeter to ensure the cable uses all the pins and all solders or wiring are intact.
Power off the computer and monitor. Disconnect the VGA cable from the monitor and the PC.
Insert the black and red test probes in the corresponding ports on the multimeter. Insert the black probe lead into the hole or port marked “+” or positive and the red probe lead into the “-” or negative port. Some multimeters have “COM” and “mA” ports, instead of negative and positive. On these types of multimeters, insert the black probe lead into the “COM” port and the red one into the “mA” hole.
Power on the multimeter and set the selector switch to the “Ohms” setting. If the multimeter has variable resistance settings for ohms, set the unit to “200” or its lowest setting.
Align the VGA cable so that you can view the open connectors on both ends of the cable. Position the cable's ends so that the broad edge of the connector is on top.
Touch the black and red probe leads together to zero the display and calibrate the multimeter.
Touch the black probe to the left-most pin on the top row of pins on one end of the cable. Touch the red probe to the left-most pin on the top row of pins on the other end of the cable.
View the ohm reading on the multimeter's display. In most cases, the resistance shown on the display should be more than zero but less than 20. If the multimeter shows “0” on the display, no continuity exists between the two pins. This is usually the result of a damaged wire or solder. In some cables, the wire might not exist at all.
Use the probes to test other pins on the cable connectors, ensuring that you touch the probes to the exact same pins on either end of the cable.
Tips & Warnings
- If all pins on the cable exhibit continuity on the multimeter display, you can use the VGA cable with monitors to attain better aspect ratio and resolution higher than the VGA VESA standard of 4:3 and 1,024 x 768. If not all the pins display signs of continuity, replace the VGA cable with a higher-quality unit.