Why do some Monitor VGA inputs not work with HDTV Tuners?

You would think a modern 16:9 TV, monitor or projector will accept an HDTV feed from our 232-ATSC series tuners, right? Or any HDTV tuner, for that matter.

The correct answer is – not always. While HDTV resolutions are part of the family of VGA, sometimes the manufacturer assumes that the set will only be fed conventional VGA resolutions such as 1280 x 768, 1280 x 1024 and so on. Since the display is 16:9, you’d think it would even prefer true 16:9 standards, at least 1280 x 720, but it just ain’t so. 1080i and 720p are always supported on Component and HDMI, not so much for RGBHV. If you set the ATSC output to 480p, that will usually work.

The odd thing is I find many $100 – $150 19-23″ desktop monitors that are perfectly happy with HDTV on the RGB port, but not expensive big screens. My personal take is that the  suppliers were too lazy to update their drivers.

Proactive Solutions

If your system design connects or routes HDTV signals to the RGBHV HD-15 port on the back of the displays, check the set’s manual on what resolutions are supported. The chart is usually in the back and is very explicit as to which it will accept. What you want is either 1080i, 59.94/29.97 Hz or 720p, 59.94 Hz. If that resolution is not listed, odds are high HDTV signals won’t work. If you’re not using a scaler/switcher to route video to the display, the set’s internal scaler has to handle all the resolutions on its own.

Postactive Solutions

In many cases, you either can’t find a TV you like that supports HD on the RGBHV port, or you need to feed the signal to a customer’s existing set. In that case,  you’ll need a scaler to convert the HD output of the tuner to a VGA resolution accepted by the display.

Our tuner has an onboard scaler, but that’s dedicated to displaying incoming 1080i/720p/480p/480i channels at a set HD output resolution. To convert 16:9 HD to 16:10 to whatever VGA, you need a scaler dedicated to that task.

VGA Scalers

There are 3 good VGA scalers by Hall Research (SC-VGA-2B), DVIGear (DVI-3221a), and TV One (1T-VS-434) that do a fine job at a sub-$385 retail cost. They’re basically identical, with a VGA in and out, and three buttons that set the output resolution. You can scale up or down, up to 1920 x 1080. Pretty simple.

There are other products by TV One, Extron and others, but the principle is the same. The input accepts HD video and ouputs a variety of VGA resolutions.

The same rule applies to video projectors, most accept HD resolutions at the RGBHV input, but not all.