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Comcast dct3416 refresh rate adjustment? Vertical Bands?

post #1 of 12
Thread Starter 
I just got my Comcast HD + DVR, and i am noticing very subtle vertical bands moving from right to left. It appears to be worst on some channels more than others. It is especially noticable on my "On Demand" selections.

It's seems as though the refresh rate is just a bit off on my cable box.

- This is the case with hdmi or component cables.
- If I change from 1080i output to 720p, it appears to be slighty less notiable.
- This is the only HD device that I have that exhibits this problem, so I doubt it's my TV or cables.

I am using this cable box with a Sony KV-36HS510.

Has anyone else seen or heard of any problems like this with the Comcast dct3416.
post #2 of 12
I have been having the same problem with my dvr. It seems to be purple banding, I noticed that you can see it more at night or in a dark room. I have also noticed that it is only on the HD chanels. I really hope it's not our tv's, because I have the kv-34hs510 witch is the widescreen version of your tv. If anyone else has noticed this problem please let us know with the model of your tv.
post #3 of 12
Thread Starter 
AVKIK, what kind of DVR brand/model do you have?

I took my Comcast motorola dct3416 back to the comcast service center and swapped the box for another of the same model, and i'm still having the same problem.

I was at my friends house the other night, and I noticed that her HD + DVR comcast/motorola box was dct3416 III. I'm wondering if getting this assumingly later model will help resolve my issue.
post #4 of 12
dtliem, I have the comcast Motorola DCT6412 III HDDVR. I wonder if it is possible for you to use her DVR with your tv, to see if the banding still occurs. I plan on calling comcast very soon to try to fix the problem. I see that you have the problem with component and hdmi, so I wonder if it's worth me trying to hook up my component wires to see if it still occurs. Right now I am using hdmi with a dvi/hdmi adapter.
post #5 of 12
Thread Starter 
Yeah, I plan to try her dct6414 III out sometime this week, when I get a chance to borrow it for an hour or two. I will post my own results when I get a chance to do so.

Now that I read that you are seeing this with the DCT6412 III, i'm not holding high hopes that it will solve my problem, but still worth a try.

I did not mention this before, but I have another hdmi device (information of which can not be disclosed unfortunately), which does not exhibit these band issues that the comcast motorola boxes to on my sony wega, which is why I am hesitant to blame the fault on the TV itself.

also if I do 720P from DVI out of my macbook pro and watch HD content, I don't get these bands either.
post #6 of 12
Thread Starter 
So, I borrowed my friend's DCT6412 III cable box, and unfortunatly, I'm still seeing the same issue.

I hope Comcast will be willing to help us resolve this issue.
post #7 of 12
Have you connected the Sony directly to the cable (by passing the box) and using the internal tuner? Broadcast HD is often carried in the clear. If the banding persists then its not the box.
post #8 of 12
Thread Starter 
Unfortunately, my model of Sony Wega doesn't have a built in HD tuner.

I have however plugged in the cable directly to test basic cable for non-HD broadcast, and I do not see the issue.
post #9 of 12
It sounds like a ground issue to me. Is your installation properly grounded? Is your wall socket properly grounded? The most common cause of these issues is people trying to use a two-prong socket to three-prong socket adapter.
post #10 of 12
Thread Starter 
bfdtv,

as far as i know i am properly grounded. just to make sure i plugged the box directly into the wall socket, and even extended it out to different sockets in my room. i still see the same issue.

my house was built two years ago, so unless the electrical wire is screwed up from the time it was built, this isn't the issue. moreover, i have had no other grounding issues with any of my media devices.
post #11 of 12
Quote:
Originally Posted by dtliem View Post

bfdtv,

as far as i know i am properly grounded. just to make sure i plugged the box directly into the wall socket, and even extended it out to different sockets in my room. i still see the same issue.

my house was built two years ago, so unless the electrical wire is screwed up from the time it was built, this isn't the issue. moreover, i have had no other grounding issues with any of my media devices.

You could have an power circuit grounding issue, but not have any problems until you add or change equipement. Every device and every interconnect is a potential source of hum.

I don't know how you checked your power grounds but it might be worth getting one of those simple and cheap circuit testers.

Have you double checked the cable grounding block at the cable service entrance? There should be a bare wire going from it to your electrical service grounding rod or to the service entrance panel box. The last comcast tech out to look into a signal strenght issue, to me that he routinely checks the block. He often replaces them them rather than just retightening the screws on the block and the grounding clamp.

You likely have alread done a web search, but there is a hum FAQ on AVS

Let us know what finally works!
post #12 of 12
I really don't think it is a grounding issue, because I have the same banding going on but ONLY on HD channels. I would think if it was a grounding issue it would be all the channels. dtliem, is the vertical banding with all of your channels or just the HD?
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