Published on 27th May, 2014 by Cable Chick

VGA Expose: Everything there is to know about VGA


VGA Expose: Everything there is to know about VGA

Learn everything there is to know about VGA, including the difference between 14-pin and 15-pin VGA cables, and why it's important to get the right one!

VGA Plug and Socket DiagramDisambiguation

Here at Cable Chick, when we talk about VGA, we're taking about the connector; the 15-pin D-SUB plug and socket that you find on the side of your laptop, the back of your TV, and the ends of our VGA cables. You'll have seen it before on computers, projectors, monitors, or even electronic whiteboards.

It became the baseline standard for the personal computer market in the 90s and held dominance until the advent of digital video. Today, VGA remains a popular legacy connection for many home theatre displays due to its low implementation cost and impressive technical capability.

What is VGA?

VGA is an analogue video standard that carries component RGBHV data from a source device to a display device. Despite being analogue, VGA is not easily compatible with other analogue video standards, and can't be connected directly to CVBS or YPbPr equipment without a separate signal converter.

Once upon a time, VGA was synonymous with a 640x480 screen resolution. But now a VGA connection can reach 1080p Full HD without breaking a sweat. As such, VGA is still an important part of our daily lives. After almost 30 years since its inception, there are some tricks to VGA you should know about.

14-Pin vs 15-Pin VGA

In the beginning, a company called ITT Cannon developed a series of electrical connectors that were compact enough to fit on ever-shrinking computer systems. One of the most common connectors of the late 80's personal computer era was the DE-9, which was used for (among other things) EGA displays and serial data links.

When IBM developed VGA, the DE-9 connector was widened to accommodate 15 pins – its other physical dimensions remained the same – and the pinhole number 9 was filled-in, effectively creating a 'key' that ensured only cables wired for VGA video could be connected.

This set a standard for VGA video cables to leave pin 9 disconnected. Some cables even went without pin 15, which was optional at the time. Despite later changes to the VGA standard from the Video Electronics Standards Association (VESA), cable manufacturers are still called upon to produce cables compatible with the old VGA standard.

To make matters worse, these VGA systems and their associated cables were still referred to and marketed as '15 pin', and continue to be so to this day.

VGA 14 Pin vs VGA 15 Pin Wiring Diagram

Modern implementations of VGA now use all 15 pins in order to enjoy a wider range of applications, particularly in the growing home theatre market. Now that digital content can be delivered to a TV instead of a computer monitor, it is vital that displays are correctly detected and identified by source hardware.

Pin 9 is now utilised for a 5v DC power rail, and pin 15 is the VESA DDC (Display Data Channel). The power line is designed to run the EDID or DDC chip inside a display so that it can be identified when it's not externally powered, while the DDC line carries that information back to the source device.

Whether or not your TV requires this power for the DDC handshake varies between manufacturers and their chosen implementations on each model of display. Some screens will happily work without pin 9 so long as they get power from the wall, while others will refuse to 'handshake' unless it's present.

Does Cable Chick Sell 15-Pin VGA?

YES. At Cable Chick, we stand by our VGA Male to Male cables between 3 metres and 25 metres. They are 15-pin connected from end to end, verified independently. If your home theatre system requires VGA with all 15 pins be connected, or you have a 14-pin cable which isn't behaving correctly, you can trust us to provide the right cable for your needs.

Unfortunately, at time of writing, our 1.8 metre VGA and extra-long VGA cables aren't guaranteed to be 15-pin connected. Similarly, our VGA extension leads are also not guaranteed. If these lengths are important to you, please contact us so we can put our Multimeter to work and find out what wiring configuration our current on-shelf supply has on a case by case basis.

Modern VGA capabilities

Being analogue, VGA can suffer from signal degradation in much the same way as component and composite video. Long cables, electromagnetic interference and splitters can all contribute to signal loss. Even on short cables, VGA is rarely as sharp as a digital link.

Unlike other standards, VGA has a unique way of managing with reduced bandwidth; most hardware has the ability to automatically lower the screen resolution in order to preserve video fidelity. For example, if a 1080p Full HD signal can't reach the display correctly, the hardware may step-down to 600x800 in order to ensure a picture is displayed. This feature is not universal, but is especially common on computer systems and from devices which support multiple resolution output settings.

As a rule of thumb, we recommend cables of no more than 5 metres to ensure full native resolution to the maximum capability of your hardware at the best possible image quality up to 2048x1536. Cables up to 10 metres may suffer from some image or colour distortion, but the impact will vary based on your environment.

Extremely long cables (over 15 metres) may be limited in quality or resolution to as low as 640x480 pixels under extreme circumstances, which is insufficient for many televisions and can result in a blank screen. Computer monitors are generally not limited on the low end, and may give better results when working over long distances.

Boosting, Splitting and Switching VGA

When you need to maintain high resolution content and still operate over long distances, or between multiple displays, we have a variety of additional hardware which can make living with VGA a breeze.

VGA splitters come in passive and active varieties. A passive VGA splitter is really only good for short distances, and we stock the following basic cable for your simple VGA splitting needs. Keep in mind this solution shows the same content on each screen:

Powered VGA splitters work nicely as boosters as well. Even if you only need to feed video to a single display, a Powered VGA splitter is a powerful tool. Under ideal circumstances, you can run high resolution images 50 metres with one of these units:

VGA Switches also come in passive and active types. Our basic passive 2-way VGA switch is a compact push-button unit which works best inside cable runs up to 5 metres, but can go a bit further depending on your hardware:

Our High-End VGA True Matrix Switch/Splitter boxes combine all of the above, with independent source and display pairing plus audio pass-through via 3.5mm stereo jacks. If you need total control over a multi-input, multi-screen display presentation, VGA Matrixes are the way to go. We even have a blog article on them!

Still stuck?

Answers on VGA aren't always easy to dig up, which is the main reason for this blog entry. If you have further questions or more information to share, please fill out the form on our Contact page.

 

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