High Def Forum
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Will SDTV display an HDTV signal?

09-03-2006, 01:40 PM
I have a Scientific Atlanta 3100HD High Def cable box from Cox. If I hook the box up to an SDTV via the component inputs will it display the high-def channels in 480i?

Currently when I use a TV that is connected to the box via S-Video it does not display any picture on the high-def channels. I only get audio.

09-03-2006, 03:41 PM
Your SDTV will only display an HD channel if it's designed to accept an HD signal. If it's truly an SDTV versus say an EDTV, chances are that it won't work for HD channels. By the way, s-video will never work since that type of input does not support HD.

09-03-2006, 05:46 PM
It depends on your STB. I have Verizon FiOS and got the Motorola HD DVR even though I did not have an HDTV then, just a digital SDTV. The Motorola DVR offers an option, I don't remember right now what it is called, that will output HD channels at 480i so they can be viewed on an SDTV. It had bars around it, but at least I could see and hear it .

You should check the configuration of your STB to see if some option will allow you to view the HD channels on an SDTV.

09-03-2006, 10:27 PM
Borromini---Well an SDTV I was looking at was hooked up at the store and it appeared to be receiving OTA HD Channels (just showing them in 480i format). However, I'm not planning on using the TV for OTA---I was planning on using the component cables from the cable box. I just can't find any documentation if the TV would display the signal from the box.

Justin---Thanks for the data. I've searched all over the Explorer 3100 settings menus but can't find anything that would change the component output from 720/1080 down to 480. But I'll keep looking.

09-04-2006, 05:06 PM
That's because you were viewing a digital SDTV, which means it has an ATSC tuner that can accept HD signals with internal circuitry to downscale it to 480i. The real question is whether that same TV could accept a 1080i/720p signal via component. :)

Just curious, why haven't you tried it yet? Do you not have a set of component cables?

09-04-2006, 07:05 PM
I haven't tried it yet because I don't have the SDTV set yet. My HDTV crashed and I don't have the cash yet to get the new HDTV that I want. So I thought in the meantime, one option would be to get a $300 "disposable" 27" SDTV set that I could use for a few months and hook it to my existing HD cable box and view all of the same channels. Hence the question about whether the SDTV would could accept a 1080i/720p signal via component. I was hoping to get the answer before I buy it. The people at the store aren't that knowledgeable.

Thanks for your input!

09-04-2006, 08:27 PM
I've searched all over the Explorer 3100 settings menus but can't find anything that would change the component output from 720/1080 down to 480. But I'll keep looking.Jet1000,

One last shot...

Again, I don't have any experience with the Explorer 3100, but I went back and looked at the User's Guide for my Motorola QIP6416 HD-DVR, and found the following:


TV TYPE: 16:9 for wide screen TVs, 4:3 LETTERBOX or 4:3 PAN/SCAN for standard TVs.

HDMI/YPbPr OUTPUT: 1080i, 720p, 480p, or 480i (if not using HDMI then it is labeled YPbPr OUTPUT)

Video Connection Options:

"Component video, HDMI, and IEEE1394 allow you to view both HD and standard TV programming. Composite video, S-video, and RF coaxial connections allow you to view standard definition TV programming; HDTV programming can also be viewed, but it will be converted to standard format."

I have highlighted the portions that I think are relevant to your situation. If, and it is a big if, your STB offers similar options, you should be able to watch down-converted HD on an SD TV.

Before buying an SD TV, why not borrow one from a neighbor and try it out?

09-07-2006, 09:04 PM

Well I don't know anyone who has an SDTV. But thanks for the information on the settings from your DVR. At least I know now what to look for as far as settings go on the cable box. Thanks!

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