DVI for HDTV

In stead of buying a larger flat screen at this time, I wanted to get by for a while using an HD monitor. I have tried three different ones, an e-Machines 21.5", Acer 23" and Samsung 23" Monitor/TV. All have DVI connectors and I got a DVI box (Scientific Atlanta 4200) from the cable company (Cablevision). None of monitors would work with this box. The Acer and Samsung have HDMI and a DVI (box) to HDMI (monitor) cable will work. So it would seem that the DVI on the monitors is the problem; however, attaching a Panasonic DMR-EA18 HDMI to the DVI input on the monitor works fine.

I am assuming that it is an issue with encryption, but does anyone have knowledge of where the problem really is? Cablevision is, not surprisingly, clueless.

Thanks

Acer and Samsung monitors claim HDCP compliant. I though it might be that simple, but it doesn't appear to be.

The monitor shows a 1080 x 1960 resolution for the cable box and I don't recall what the DVR shows, but it isn't bluray so it would have to be 720P or 1080i I would assume.

Using a 4250 HD box and HDMI you get full HD on all the monitors.

That doesn't seem to be the issue here. The STB shows 1080i and the monitor shows 1920 x 1080i. But the HD is through HDMI instead of DVI. With DVI I don't get a picture, though the box states DVI is HDCP compliant on DVI.

In other words everything should work, but it doesn't.

That is a possibility; however, when I spoke with Cablevision's tech support people they claim that the DVI should work. If it were not operable then you would think they would know that. For HDMI you need a different box, so it wasn't like they may have thought I was looking to use HDMI and was using DVI.

There isn't a difference in charge, but this is a knowledge issue rather than just trying to solve a problem. I know I can get HD with the 4250 and HDMI on monitor; I want to understand why I can't get HD with 4200 and DVI. Cablevision says I should be able to do so, but it hasn't worked. Monitor manufacturers don't have an answer. Both sides blame the other and nobody has the knowledge to help.

Manufacturers put trained monkeys in tech support position. Even the US based ones have no tech know-how. Someone at Samsung tried to tell me that DVI is an audio only connection. So I am trying to troubleshoot myself to understand why something that should work doesn't.

Is there anything one can look at regarding specs to see if there is compatibility or any way to confirm or is it just that it works or it doesn't?

Thanks all for the thoughts and comments.

From Walford's comments I can only conclude that DVI has to be treated as a worthless connection. That doesn't mean that it can't and doesn't work, but that when evaluating it you must ignore it in the analysis of a product/setup and be very happy if it in fact does give usefulness.

This seems to be the norm for TV connections; however, I don't understand why DVI seems to be so dependable for computers, but not for TV. Is it because TV set top box vendors didn't follow the standards that computer video vendors did?

Walford,

I guess this is what I don't understand. Is DVI a different standard for PC than cable set top boxes? I can get 1920 x 1080 from my PC card to monitor by dvi to dvi connection, but I cannot get that same resolution to work with the same monitor if the source is a Scientific Atlanta 4200HD dvi to dvi connection. Where is the problem? The SA 4200 isn't generating a compatible signal?

But if I set my PC resolution to 1920 x 1080 how is that different from 1920 x 1080 from the STB?

I tried four different units with the SA 4200. One was a Samsung 2333HD with DVI and HDMI and 1920 x 1080HD resolution. I don't recall if they claimed HDCP for the DVI, but calling their tech support could not get anyone who knew anything about HD connectivity beyond how to plug a plug in.

The second was an eMachines E211H which was 1920 x 1080 HD with DVI, but doesn't say anything about HDCP and again there was no ability to discuss with tech support.

The third was an Acer X223HBD with DVI which stated HDCP and 1920 x 1080 HD.

The last was Acer H233H BMID which has DVI with HDCP, HDMI and 1920 x 1080 HD. All four can produce picture with 1920 x 1080 output from the PC. None of the four could produce a picture with dvi to dvi connection from SA4200 STB (set at 1080i). The Samsung and H233H also have HDMI and could produce pictures with DVI (STB) to HDMI (monitor) connection.

A switch to a SA4250 which has HDMI Connector instead of DVI on the 4200 gave no picture on any monitor with an HDMI (STB) to DVI (monitor) connection, but did give picture with HDMI to HDMI on the two that could accept it.

Lastly, DVI out from Panasonic DVD recorder to DVI on H233H works.

So the problem seems to be getting an HD signal from Cablevision to a DVI input. Is it possible that there is something in the signal from Cablevision that is causing this or is it only the Scientific Atlanta box that could be at fault.

Cablevision claims that DVI on 4200 works and there should not be any issue but has no one with enough tech knowledge beyond that and blames everything on video vendor.

None of the monitors give you options for setting resolution or refresh rates; they only play what is provided.

Walford, the problem also occurs if I use a 4250HD with HDMI and connect that to DVI on the monitor. In other words there is no HD combination that will allow a Cablevision box to work with a DVI monitor connect, even though the monitor can produce a picture if you use the HDMI connector.

Ken D's comment "DVI video output into most DVI HDTV inputs is fine. It's when you use a PC monitor with DVI video that issues occur." Leaves me wondering why. If DVI works well with a TV why would a PC monitor be different. Other than a built in tuner they should be pretty much alike I would think.

Also DVI is a standard so if a PC puts out a DVI string then any DVI device should be able to receive it. It appears the problem is that problem is that the DVI standard is broader or looser or whatever and so you may not be able to replicate the receiving requirements of the output. Is this fair to say?