Hi Everyone,

Will try to make this brief, since reading long posts can be tedious.

For the last month or so, my Comcast reception looks "grainy," starting mainly at night until the next morning. It happens during the day for 20 to 30 minutes, but then resolves itself. (It is not a digital problem, like tiling, but one that looks like electrical interference.)

Comcast has checked the lines inside my condo and to the building. They have changed out amps that service my floor and the floors above me for the building.

They have been able to see it on one of their office sets that is connected to the same secondary hub as I am, but not always when it is happening on mine.

My neighbors are not experiencing it, but they may not notice, since there is a picture, but it is just a little "fuzzy."

When it happens, it happens on all four of my TVs, and on all channels.

I have an new Samsung HL61A750, but the problem started about a month after I got it. Other than that, I have not changed equipment or appliances in the four years that I have been in this condo. Also, according to my property manager, my neighbors have not purchased any new appliances in the last few months. (It is a small building, and the elevators have to be padded for anything being brought in like that, so he usually knows these things.)

There is some new apartment construction across the street and the first phase was just brought online about the time that this began. The second phase is under construction. They have been working on the phase one units, having discovered some issues, but have not told me what they are. I do know that they are on the same secondary hub as I am. But, Comcast is starting to say that it is not related to them, but, instead, some "outside" source.

Any thoughts appreciated!

How do you tune the channels? Cable box, HDTV, other box?

What channels? 1-99, all of them, HD only?

How do you tune the channels? Cable box, HDTV, other box?

What channels? 1-99, all of them, HD only?


I have four HD-DVRs, all used for tuning. They are all loaded with the same package, which includes all the movie channels. Basically, they have everything except extra sports packages or Spanish language packages.

When it happens, it is on all my channels, including SD and HD, and all of the basic, expanded, and premium channels.

Does this answer the question? And, thank you!

P.S. It happens every night, without exception.

It certainly appears to be electrical interference from an appliance, a furnace blower motor, or a faulty floursasnt lighting. However, it is not clear if the problem is coming over the power line or your cable service line.
Can you connect an antenna to any of your set so that you can see if the problem is coming over the cable or not?

It certainly appears to be electrical interference from an appliance, a furnace blower motor, or a faulty floursasnt lighting. However, it is not clear if the problem is coming over the power line or your cable service line.
Can you connect an antenna to any of your set so that you can see if the problem is coming over the cable or not?


Our building has an antenna, but the property manager said that no one is hooked up to it and that it has not been modified for the digital changeover.

When I try to scan for OTA on my HL61A750 (the newest technology of all of my sets), it does not pick up channels and I cannot direct tune them either. If I am reading the manual correctly, I need an antenna or set top box, I guess. I never use OTA, and I do not know much about it. I kinda thought that the set had the tuner, but maybe I need something in addition to that?

Also, I called the new apartment complex office across the street. Their first tenants moved in about when this started happening for me. Their manager said that their tenants have been having problems with Comcast "powering" (her word). She is going to have their maintenance manager call me, since he has been dealing with Comcast on this. You may be on to something with the electrical, since they are on the same hub as me.

Am really, really appreciating the help here!

P.S. Thank goodness it is not happening at this minute, because am watching the shuttle launch on HDNet...Wow!

Our building has an antenna, but the property manager said that no one is hooked up to it and that it has not been modified for the digital changeover.There is no antenna modification needed for the 'digital changeover'. Antennas for analog TV are the same as for Digital TV (DTV); VHF, UHF or a combo.

When I try to scan for OTA on my HL61A750 (the newest technology of all of my sets), it does not pick up channels and I cannot direct tune them either. If I am reading the manual correctly, I need an antenna or set top box, I guess. I never use OTA, and I do not know much about it. I kinda thought that the set had the tuner, but maybe I need something in addition to that?What do you have connected to the HDTV? The Comcast cable or the antenna from the building?

Checking the specs, your HDTV has a DTV tuner & QAM digital cable tuner. If the building antenna is still functional, you may be able to get at least one DTV station to use as a test. If you connect the Comcast cable, you should be able to get the local HD that Comcast carried in your area.

The Op's ...750 LED digital tuner supports either OTA "ATSC" digital or cable clear QAM digital programs see the following spec:

http://www.samsung.com/us/consumer/detail/spec.do?group=televisions&type=televisions&subtype=dlptv&model_cd=HL61A750A1FXZA&fullspec=F


Also since digtial tuners are very subject to problems with multipath signals there are now some tuners that are very directional to eliminate this problem and these are advertised as digital tuners but they are not required if multipath reception is not a problem.

The Op's ...750 LED digital tuner supports either OTA "ATSC" digital or cable clear QAM digital....Thanks for the correction.

The Op's ...750 LED digital tuner supports either OTA "ATSC" digital or cable clear QAM digital programs see the following spec:

http://www.samsung.com/us/consumer/detail/spec.do?group=televisions&type=televisions&subtype=dlptv&model_cd=HL61A750A1FXZA&fullspec=F


Also since digtial tuners are very subject to problems with multipath signals there are now some tuners that are very directional to eliminate this problem and these are advertised as digital tuners but they are not required if multipath reception is not a problem.


Sorry for these rookie questions, but what are:

a. Multipath, and
b. ATSC (I know what NTSC is).

Also, Comcast has been pretty dedicated. Three techs just left (11:30 p.m. MDT).

walford, they considered your thoughts about the electrical and ran an extension cord to the A750 from an electrical outlet in their equipment room on my floor and, oddly, that cleared up the problem on the A750 and all of my other TVs, too.

Then, when they returned the A750 to my apartment source, it stayed cleared up. This is the first time in over a month that the problem has cleared up at night. I should add that I have an APC H10 power filter on the A750.

Usually it starts to deteriorate around ten, or so, and stays degraded until seven or eight in the morning. (When it happens during the day, it resolves itself after about 20 or 30 minutes.)

They are going to come back tomorrow and hook up a new type of HD-DVR that has not been "deployed" into the field in Denver yet and also keep my current box hooked up to see if it makes a difference. They said that it may handle their new compression better. (I understand that just enough to be dangerous...LOL!)

Thank you so much, everyone, for helping me!

Do they see it at the Comcast office?

It could be interference originating at the Comcast head end, not locally and most people are happy enough just to get a picture of any kind and that, coupled with the fact that it happens late at night, may mean they haven't had other complaints.

It could also be electrical interference due to a problem with the cable entering your building.

Just a thought.

I should add that I have an APC H10 power filter on the A750.

Suggst trying a hookup that bypasses the filter. Slim chance for a fix, but an easy test. -- John

Multipath is when your antenna is receiving both the signal from the transmitter and reflected signals from nearby buildings or other objects. Such as large trucks on a close by freeway.
NTSC is the US standard for analog TV formats.
ATSC is the US standard for digital TV formats.
See the following link.

http://www.hdtvprimer.com/ISSUES/what_is_ATSC.html

The esperioence with the extension cord is very interesting.
It appears that the 750 itsself was involved in the generation of or amplification of the interference even when in "off" standby mode and just unplugging it from the wall and plugging it back in changed the symtoms.

Do they see it at the Comcast office?

It could be interference originating at the Comcast head end, not locally and most people are happy enough just to get a picture of any kind and that, coupled with the fact that it happens late at night, may mean they haven't had other complaints.

It could also be electrical interference due to a problem with the cable entering your building.

Just a thought.

They were able to see it a couple of times on a set that was on the same secondary hub from the head end, but other times they could not. You read my mind on whether other people would report it. When I asked them that the other day, they said that there were thousands of people on the secondary hub, and even more on the head end, many of whom are videophiles and some of them would have called.

They checked all the lines coming into our building, all of the lines in all of the equipment rooms inside the building, and in my apartment. They all came up clean.

I cannot help thinking that something is going wrong with the new apartment complex diagonally across the street, since they just started taking in tenants about the time this began. The tenants have been having problems with their boxes. If I understand correctly, the boxes are self-power-cycling, with no impetus.

When I bought this condo, I did some major remodeling (for floor plan reasons, as this is a fairly new building). So, just to be "safe," I have a call in to my electrician to check things out. And, maybe he has seen or heard of this.

Thanks!

Multipath is when your antenna is receiving both the signal from the transmitter and reflected signals from nearby buildings or other objects. Such as large trucks on a close by freeway.
NTSC is the US standard for analog TV formats.
ATSC is the US standard for digital TV formats.
See the following link.

http://www.hdtvprimer.com/ISSUES/what_is_ATSC.html

The esperioence with the extension cord is very interesting.
It appears that the 750 itsself was involved in the generation of or amplification of the interference even when in "off" standby mode and just unplugging it from the wall and plugging it back in changed the symtoms.

Hmmm, I wonder if that means that the APC H10 is not doing its job. It is about four years old. I thought it was supposed to keep the line on an even keel, among other things.

The other night, out of frustration, I started turning off the circuit breakers by zones in my condo to try to isolate any issue. I even turned them all off at one point and just let it "sit" for about 15 minutes, but when I turned things back on, the problem was still there.

I did, briefly, unplug the A750 from the APC H10, but did not try plugging it directly into the wall, so I suppose I should try that. It makes me a little nervous to not have any protection, though, because Denver gets a lot of lightening in the spring and summer.

I am going to see what my electrician says and tell him your thoughts on the A750 generating something. At least it is under warranty, so it should not be too expensive to address if it is that.

You sure know a lot about electrical! I am quite appreciative!

Suggst trying a hookup that bypasses the filter. Slim chance for a fix, but an easy test. -- John

Thanks, John Mason. (See post just above.) It is so nice to come here looking for help and finding people who are willing to do so!

Turning off the circuit breakers would have had the same effect as unplugging it from the wall, However, unpugging just the 750 electric and cable connections and seing if the other sets still have the problem sould enable you to know if the 750 itself is in any way resposible.
John's idea is also a good one as a test.

Turning off the circuit breakers would have had the same effect as unplugging it from the wall, However, unpugging just the 750 electric and cable connections and seing if the other sets still have the problem sould enable you to know if the 750 itself is in any way resposible.
John's idea is also a good one as a test.

Okay, I am going to try that. In a little while, I am going to an appointment. When it starts again, after I return, I will do it and let you know what happens.

At the risk of being repetitive: Thanks!

Turning off the circuit breakers would have had the same effect as unplugging it from the wall, However, unpugging just the 750 electric and cable connections and seing if the other sets still have the problem sould enable you to know if the 750 itself is in any way resposible.
John's idea is also a good one as a test.

Okay, I tried that last night, but no matter which television I left unplugged, the others still manifested the issue.

This has been going on for over a month...really big sigh...but I am not giving up yet. Besides, I do not want to try satellite, because I am afraid that I will be just exchanging one problem for another. Being in a condo, I am also limited in my direction available, unless something has changed in recent years and that does not matter.

Now I am confused I thought that you said that when the cable company used an esxtension cord to your 750 that the problem did not occur which would certainly indicate to me that there is a problem the with power distribution box within your unit.,

Now I am confused I thought that you said that when the cable company used an esxtension cord to your 750 that the problem did not occur which would certainly indicate to me that there is a problem the with power distribution box within your unit.,

That is true about the problem clearing up when they did that. So, last night when the problem returned (big time!), I tried doing what you and John Mason suggested, which was to unplug the A750 to see if the problem went away on my other sets, but it did not. So, just for the heck of it, I tried unplugging each of my other sets while the others were on, to see if any of those were a culprit, but nothing cleared up the problem.

When I remodeled my condo, work was only done on about half of it. At that time, there were new codes requiring that new electrical work be covered by GFCI. So, three of my four sets are on that same circuitry (if that is the correct word), while the remaining one is not. I keep trying to think of ways to isolate the issue, but am at a loss.

The building's electrician (not mine...I cannot reach him), with whom I spoke on the phone said that he doubts that it is an electrical issue, because I am not experiencing problems with any other electrical outlets or appliances.

Did you also disconnect the cable connection from each of the sets when you unplugged their power connection?

Did you also disconnect the cable connection from each of the sets when you unplugged their power connection?


No, only the one that they experimented with the other night, since I just disconnected the APC H10, which powers everything related to that particular TV.

I did not think to do what you are asking, so I will do that tonight if (more likely, when) it happens.

On another note, they just connected a second cable box to the A750. They left my other one on a different HDMI port, but are not charging me extra, since this is a troubleshooting scenario. It is a Motorola DCX3400 and it is really nice. It has a lot of different resolution settings. It has a 250 GB hard drive. And it has a faster response time on my larger set than the older one.

The tech supervisor said to call him tonight if it happens even if it is 1:00 a.m., and he will come over. It is accommodating, but I think that they are stumped and trying to say that they "tried," but may not know what they are seeing.

My electrician still has not called me back, which is really irritating me.

Thanks for telling me to unplug the cable connections. Do you think that I should also unplug the power from the cable boxes?

The more you units disconnect/unplug the more units you eliminate as a possible cause.
You might try disconnecting/unplugging all connections except those to the 750 and see if the 750 has problems at 1am.
Does the cable company use a powered splitter to run lines to all of your outlets?

The more you units disconnect/unplug the more units you eliminate as a possible cause.
You might try disconnecting/unplugging all connections except those to the 750 and see if the 750 has problems at 1am.
Does the cable company use a powered splitter to run lines to all of your outlets?

No, they use a non-powered splitter. But, the way they have it is this:

The signal comes from a tap on my floor into a drop into my condo unit. At that point, it goes to a 3-way splitter. One of the lines from the splitter goes to one of my four TVs. The other line of the splitter goes to the remaining three TVs via another three-way splitter. The line that goes to the three TVs has a POWERED amp. on it. The amp. has been changed and they have also tried it without the amp., but they said that the signal at the TV that is farthest from the drop was reading too low.

The supervisor who was here today, when asked, said that it is not always a good idea to do what they call a "home run," which is fishing lines from the drop to each TV individually, because the signal can be too strong. He got me to thinking, though...maybe the next thing to try would be to move the amp. from the beginning of the three-TV line from the splitter to just the one at the farthest point.

walford, you are so kind to keep helping me!

I disagree with the supervisor since if there were not splitters and only one TV then the signal to your condo would not be "too strong".
I suggest that you test with the line to the second splitter disconnected so that you are only feeding the one TV that is connected to the first splitter and that you put your power filter on the line for that one TV.
We need to get down to a very simple configuration that works and then add units till we find what is causing the problem.
Since I am retired helping to resolve problems such as yours is one of my hobbies.
Moving the amp to the end would not help since it would only be amplifying the too weak signal that it would be receiving.
I am suspecious of the amp getting interference over its power line.
Which splitter is the 750 connected to?

I disagree with the supervisor since if there were not splitters and only one TV then the signal to your condo would not be "too strong".
I suggest that you test with the line to the second splitter disconnected so that you are only feeding the one TV that is connected to the first splitter and that you put your power filter on the line for that one TV.
We need to get down to a very simple configuration that works and then add units till we find what is causing the problem.
Since I am retired helping to resolve problems such as yours is one of my hobbies.
Moving the amp to the end would not help since it would only be amplifying the too weak signal that it would be receiving.
I am suspecious of the amp getting interference over its power line.
Which splitter is the 750 connected to?

The 750 is connected to the line that has the three TVs on it. Disconnecting that second splitter will be a bit of a hassle, because it is behind a wall plate that is behind an armoire. But, the armoire is relatively easy to move out. I just hope that the tech manager that is working on this will try this. He probably will, since he seems amenable to trying things. They did move the armoire last week and test the signal coming out of that second splitter and, at that moment, it was testing clean and with a good signal. He concurs with what you said about moving the amp.

The problem only occurred briefly last night, rather than the whole night as has been the case since it started. Last night and the night before last are the only two nights in about a month that it resolved itself pretty quickly. I keep wondering if there are some sort of temporary power suppliers for the nearby construction. They are not working at night, but I am wondering if there could be some surges from that.

The tech manager is making himself available for the next week or so to come over at any time during the night when it happens. So, I am going to ask him to try your suggestion if/when he comes over.

My electrician finally called me back last night. It appears that he has been in CA working on a project and his phone was not ringing when he got calls. He said the same thing that our association's electrician said...that if it is an electrical problem, in all likelihood, it would be showing up in other things like lights and appliances. He is going to come over mid-week next week when he returns to double check things. I will ask him about doing the "home run" thing. It should not be too hard (for him, anyway), since he has seen the condo before the dry wall was put up on the new walls and he was here when we took down the old ones. There are also a couple of places where the ceiling is accessible, like some water shut-off panels.

An electircal RF interference problem woud not show up in another appliance since all the other appliances are only concerned with obtaining the normal electrical power anRF interference has absolutly nothing to do with that since it does notthing to interrupt the power itself.
If it is hard to get to the second splitter then disconnect the line from the first splitter to to it and only try the TV connected to the first splitter.
If the 750 is connected to the second splitter and the second splitter is located behind the 750 then I am even more suspsious of the second splitter and it's possible reception of interference from the 750 itself.

An electircal RF interference problem woud not show up in another appliance since all the other appliances are only concerned with obtaining the normal electrical power anRF interference has absolutly nothing to do with that since it does notthing to interrupt the power itself.
If it is hard to get to the second splitter then disconnect the line from the first splitter to to it and only try the TV connected to the first splitter.
If the 750 is connected to the second splitter and the second splitter is located behind the 750 then I am even more suspsious of the second splitter and it's possible reception of interference from the 750 itself.

The second splitter is not behind the 750. It is behind a 37" Aquos in the master bedroom. It provides the signal for that one, then splits off to the 750 in the great room and a 32" Samsung LCD mounted on the wall in the master bath. The 37" and the 32" are both 720p/1080i LCDs and are about four years old. They were purchased when I remodeled and nothing has changed with regard to their positions or their wiring since then.

I worry a little that it may be something with the 750, but I had it for about a month before this started happening. It seems like a problem like this would show up right away, but you know more than I do.

Is RF interference a matter for my electrician or Comcast? It is super-easy to get to the first splitter, btw.

Thank you...again!

Well then do some testing with only the one TV connected to the first splitter without the cable to the second splitter connected.
Maybe you will have some different results if you do that tonight.

Well then do some testing with only the one TV connected to the first splitter without the cable to the second splitter connected.
Maybe you will have some different results if you do that tonight.

Okay, I will. I will write back to you tomorrow and tell you what happened. I have to wait for the problem to manifest to do it.

Other thoughts:
Are you watching HD programs that are filmed with HD cameras? SD programs or HD programs containg upscaled SD content will look grainy on a 1080p TV.
When does Comcast download the program guide updates?

Other thoughts:
Are you watching HD programs that are filmed with HD cameras? SD programs or HD programs containg upscaled SD content will look grainy on a 1080p TV.
When does Comcast download the program guide updates?

The thing is, when it happens, it happens on all channels: SD, HD, and HD that is really upscaled SD. It happens on basic, expanded basic, and premium channels. Last night was the first night in over a month that it did not happen at all. It is happening a little this morning, but I think that the manager assigned to this is approaching it from the point of view of proving that he has been "available," and it is not a Comcast problem. So, if it is happening just a little when he comes, he says that it is not an issue.

This morning I called the manager of the executive customer service reps. in HQ, with whom I have been speaking on and off, and presented my dilemma, which is: The local manager assigned to the issue is making himself available at even ridiculous hours, but appears to be approaching it with the idea of proving that it is not a Comcast issue, thus limiting the options to explore. It is difficult to be sooooo accommodated, yet appear to be complaining, which is the "game" I feel is being played. Maybe I am mistaken, but that is how it is appearing.

If it is interference then we still do not know the source or if it being tranmited over the cable line or the power lines.
I suggest the following assuming you have a DVD player connected to one of the systems.
When it happens switch to the DVD player and see if it still happens?
If it does then disconnect the cable or STB connection to the TV and see if it still happens with just the DVD player.
Do all the sets have a digital cable STB connected? If yes are they all PVR units also?
When you say grainy do you mean grainy as in poor upscaling or do you mean pixelated (groups of pixels cobined).
Does it happen on an analog broadcast?

If it is interference then we still do not know the source or if it being tranmited over the cable line or the power lines.
I suggest the following assuming you have a DVD player connected to one of the systems.
When it happens switch to the DVD player and see if it still happens?
If it does then disconnect the cable or STB connection to the TV and see if it still happens with just the DVD player.
Do all the sets have a digital cable STB connected? If yes are they all PVR units also?
When you say grainy do you mean grainy as in poor upscaling or do you mean pixelated (groups of pixels cobined).
Does it happen on an analog broadcast?

Per your suggestion, I checked and it is happening on the DVD player. The problem looks to be more like you describe as poor upscaling, rather than a digital problem, such as tiling or pixelation. It is kind of like what old tube TVs looked like if the sharpness is turned up too high (but the new DCX3400 HD-DVR that they just hooked up actually lets you adjust the sharpness output of the box, and adjusting that does not help...am using just as an illustration.) Or, it looks like those TVs could look when running a vacuum.

To be honest, I only know of one channel that is, for sure, still broadcasting in analog here, in Denver. There may be some others, but I am not certain. The one that still is broadcasting in analog was never that great, not just in my condo, but everywhere, to begin with.

When I saw the interference on the DVD player, I called the tech and told him what you said to try and we are going to see if my electrician can get some idea when he gets back next week. He (the Comcast tech) said that he has seen instances in which a problem can manifest only with TVs, and not with other lights or appliances.

Edit: Adding that I do not know what STB or PVR mean, but all four of my TVs have HD-DVRs on them, and the 750 now has two, temporarily, for troubleshooting purposes.

Does this sound like a good plan to you, or is there something else that I should be doing?

Thanks, walford...my hero!

I was assuming that your tuners supported analog channels 2-76 in addition to higher numbered digital channels. I would expect grainy content on the analog channels any time of the day. The DCX3400 is I beleive an all digital unit which means that is also receiving channels 2-76 in digital format.
What are the other DVR model numbers?
STB stands for Set Top Box which is what your HD capable DVR's are.
PVR (personnel video recorder) and DVR(digital video recorder) are the same in your.
If the DVD was grainy with out any connection from a DVR to the TV you used it with then the problem is not interference coming over the cable lines if in fact it is interference.
What is baffling is that the probem only happens at night or early morning.
So if you play a DVD during the day the problem does not happen?
Try recording a know HD channel broadcast as indicated by no side bars being present during the day when the problem is not happening and then play back that recording at night. you might also try the reverse record a true HD program that is grainy at night and play it back in the daytime.
Many people suggest turning sharping all the way down.
The DCX3400 is I beleive an all digital unit which means that is also receiving channels 2-76 in digital format.
What are the other DVR model numbers?
Is it at all posible that the problem is light source dependent Ie. interion lights at night and strong daylight on most days. The default settings of HDTVs are designed for bright store showrooms and not for normal homes so the brightness levels are normally set too high.
What output resolution settings are you using from your Motorola DVRs over w]hat interface to your TVs? I would assume 1080i for 16:9 content and 480i for 4:3 content over HDMI.

I was assuming that your tuners supported analog channels 2-76 in addition to higher numbered digital channels. I would expect grainy content on the analog channels any time of the day. The DCX3400 is I beleive an all digital unit which means that is also receiving channels 2-76 in digital format.
What are the other DVR model numbers?
STB stands for Set Top Box which is what your HD capable DVR's are.
PVR (personnel video recorder) and DVR(digital video recorder) are the same in your.
If the DVD was grainy with out any connection from a DVR to the TV you used it with then the problem is not interference coming over the cable lines if in fact it is interference.
What is baffling is that the probem only happens at night or early morning.
So if you play a DVD during the day the problem does not happen?
Try recording a know HD channel broadcast as indicated by no side bars being present during the day when the problem is not happening and then play back that recording at night. you might also try the reverse record a true HD program that is grainy at night and play it back in the daytime.
Many people suggest turning sharping all the way down.
The DCX3400 is I beleive an all digital unit which means that is also receiving channels 2-76 in digital format.
What are the other DVR model numbers?
Is it at all posible that the problem is light source dependent Ie. interion lights at night and strong daylight on most days. The default settings of HDTVs are designed for bright store showrooms and not for normal homes so the brightness levels are normally set too high.
What output resolution settings are you using from your Motorola DVRs over w]hat interface to your TVs? I would assume 1080i for 16:9 content and 480i for 4:3 content over HDMI.

Actually, I have tried recording programs when the problem is occurring and when it is not. In both cases, when played back, the recordings reflect what is happening at that time. In other words, if the problem is occurring, then the playback looks like the problem, regardless of the state of things at the time of recording, and vice-versa. The same is true for the DVD playback.

With regard to lighting: It is the same lighting that I have had for four years. My condo unit is a corner unit with lots of windows and receives a lot of daylight. This will drive the environmentalists crazy, but, even during the day, I have a few lamps on, with their dimmers all the way down, in case I come in after dark, and I have forgotten to turn something on (single woman, and all that jazz). But this is the same scenario that has existed since I have been here, with no problems until now.

The other boxes are: Three (3) 3412s and one (1) 6412. All of them are the same boxes that I have had for four years, except one of the 3412s had to be changed out last year when Comcast did a software upgrade and it caused that one to keep freezing up.

The output settings are set to 1080i for 16:9 and stretch (from the Comcast box, not the TVs) for 4:3. (I just prefer short, fat faces to the black bars on either side.) The one exception is the 6412, which is the 32" LCD in the master bath, which is set to 720p instead of 1080i, because, for some reason, that looks better on that one. The 6412 does not have an HDMI port and uses component.

There is an antenna on the roof of our building, but I do not believe that I have an outlet that connects to its tap, unless I take the tap from the cable room on our floor and connect it to the antenna tap. Our Property Manager says that he does not believe that anyone in the building even uses it. Everyone has chosen Comcast. (There is a long story having to do with the original developer's contract with a satellite provider that explains why none of the 65 units' owners have chosen to go that route...will not bore you.)

Insofar as the sharpness setting, I have always kept them all the way down. When the problem is occurring, I have tried playing around with the sharpness on the 750 and get some very slight improvement on the graininess with the sharpness turned all the way up, but not enough for that to be a remedy.

Have I answered everything that you are asking?

P.S. When the problem is not occurring, I do get a slightly nicer picture on the 750 with the DCX3400. Also, unlike my other boxes, there is an improvement in the picture when the DCX3400 is set to Y C C 4 4 4 color space, rather than RGB (referring to setting on the box, not the TV).

I believe that your TV will do a better job upscaling and stretcing then your cable boxes will and with the TV you get the benefit of normal linear stretch or panaoramic stretch will stretches the sides more then the middle avoiding the fat face syndrom of linear stretch when it is receiving 4:3 content.
The 32"LCD probably has a 1366x768 native resolution so sending 720p to it would be better.
I was not trying to get you to use an antenna to receive analog cable I was trying to get you to watch channels 2-67 on your older DVRs since are receiving chanels 2-67 with built in analog tuner instead of with their digital tuner. Since the cable cominng out of the wall has both analog and digital signals.
I started thinking of the lighting when you said that the problem started when a new ap-artment house was going up across the street.
It certainly now appears that the problem is not caused by Comcast.
Have you also worked with the brightness, especially lowering it at night, contrast, and other settings such as temperature and DNIE when receivig both DVD and when receiving HDMI content on your 750 since all of the color settings are set and saved separately for each interface.
Going back to the use of the extension chord test. Was the extension chord connected diretly to your 750 or to the power conditioner? Was the power conditioner totally unplugged at the time? What other devices are connected to the Power conditioner?
Do you regularly record any programs using DVRs at night?

I believe that your TV will do a better job upscaling and stretcing then your cable boxes will and with the TV you get the benefit of normal linear stretch or panaoramic stretch will stretches the sides more then the middle avoiding the fat face syndrom of linear stretch when it is receiving 4:3 content.
The 32"LCD probably has a 1366x768 native resolution so sending 720p to it would be better.
I was not trying to get you to use an antenna to receive analog cable I was trying to get you to watch channels 2-67 on your older DVRs since are receiving chanels 2-67 with built in analog tuner instead of with their digital tuner. Since the cable cominng out of the wall has both analog and digital signals.
I started thinking of the lighting when you said that the problem started when a new ap-artment house was going up across the street.
It certainly now appears that the problem is not caused by Comcast.
Have you also worked with the brightness, especially lowering it at night, contrast, and other settings such as temperature and DNIE when receivig both DVD and when receiving HDMI content on your 750 since all of the color settings are set and saved separately for each interface.
Going back to the use of the extension chord test. Was the extension chord connected diretly to your 750 or to the power conditioner? Was the power conditioner totally unplugged at the time? What other devices are connected to the Power conditioner?
Do you regularly record any programs using DVRs at night?

The DNIe is grayed out on the 750, except in Dynamic Mode, which is, well, too dynamic. The DCX3400 has an amazing number of user controls compared to the older boxes. It has a setting that lets me just set it at "Native" and I can tell it that my TV is capable of 1080p/24fps. So, I just now set it at that, and apparently that sets it at the nature of the broadcast signal. I am assuming that because it is changing the "Info" display from the TV from 1920X1080i to 1280X720, just by changing the channel on the HD channels. The "Info" is blank on the SD channels...hmmm, interesting. (The faces on SD are still a little short and fat, but less so, and there is more clarity.) There is a definite picture quality improvement! Thank you!

There is a bit of a response delay when changing from one resolution to another, but I think that it may be worth it for the better picture. (Also, I turned up the sharpness on the box, not the TV, since changing the setting seemed to need that. The box has five settings for sharpness, with 5 being the highest. I moved it from 3 to 4.) Thank you!

Also, the extension cord experiment bypassed the power conditioner, but, last night, when the problem was occurring, the DCX3400 was plugged into the wall, not the power conditioner, while the 3412 was plugged into the power conditioner. Also, everything except the 3400 is plugged into the power conditioner.

The problem is not occurring at the moment. If I wanted to see if the power conditioner is a problem, do you think that I should wait until the problem occurs and then try disconnecting things from the power conditioner and just plug in the TV and cable box without it and then add one additional component at a time? Or, should I do that now and see if that prevents it from occurring? I am kinda assuming from your questions that you are wondering if the power conditioner is causing a problem.

Do you regularly record any programs using DVRs at night?

Forgot to answer this: Yes, and I have some stored from before the problem began, and even from before I got the 750. When I play those back, they reflect the problem if it is occurring, and, if it is not happening, they do not reflect it. Some are programs like, "Ugly Betty" and "Grey's Anatomy," and some are movies.

What I was trying to understand was if there was a relationship between recording on on of PVRs and the grainy content.
Yes, I suspect that the power conditioner may be putting out the interference on the power line itself or due to some device connected to it such as an active PVR.

What I was trying to understand was if there was a relationship between recording on on of PVRs and the grainy content.
Yes, I suspect that the power conditioner may be putting out the interference on the power line itself or due to some device connected to it such as an active PVR.

So, should I disconnect the power conditioner now, or wait until the problem is happening?

Thanks, for the billionth time!

First lets try to make the problem happen with every thing connected normally.
Start a recording using each of the DVRs connected to the 750 and with the 750 also watching LiveTV.
Does this make the problem happen?

Whil watching a 4:3 aspect ratio program on the TV see if you can change the picture size mode from linear stretch to non-linear stretch or panororamic mode.
Let me know if by operating both 750 PVRs and the TV did the problem occur?

Neither of the above two scenarios caused the problem to start.

The first sugestion was only about how to eliminate fat face when receiving 480 it did not have anything to do with the grainy problem.

I suggest that tonight you disconnect all connections to the power conditioner and to the both PVRs on the 750 and that you only watch a DVD on the 750.

I suggest that tonight you disconnect all connections to the power conditioner and to the both PVRs on the 750 and that you only watch a DVD on the 750.


Hi, walford,

It did not do it last night, at least while I was home. I am planning to follow your suggestion at the next occurrence. I wonder if it will clear up on its own, since there have been a few nights this week when it did not happen, compared to every night for a month prior to this. Just thinking "out loud."

Are you using the value settings for the differnt color options for the 2 pvrs and for the DVD if it is connected to the 750 also.
I just read through the 750 user manual and realoized that you do not have the parnoromic or non linear stretch mode for 4:3 content.
Another idea instead of incandescent lights on a dimmer is to use small motion sensor night lights instead. I have 6 of them in my home so even the bathrooms can be wondered into in the dark.

Are you using the value settings for the differnt color options for the 2 pvrs and for the DVD if it is connected to the 750 also.
I just read through the 750 user manual and realoized that you do not have the parnoromic or non linear stretch mode for 4:3 content.
Another idea instead of incandescent lights on a dimmer is to use small motion sensor night lights instead. I have 6 of them in my home so even the bathrooms can be wondered into in the dark.

But, I can set the 750 to 16:9 on all of the settings: Standard, Movie, and Dynamic. Also, with the new Comcast box, when I set it to "Native" and 1080p/24fps, it did reduce the "fat face" some, even when set at 16:9.

I am not sure what you mean by "value settings," but am assuming that you mean the different modes: Standard, Movie, and Dynamic. This set is pretty nice for my lay eyes, right out of the box. It has a slight red push tendency that some fellow owners have noted, as well, so I have the Tint adjusted slightly for that and also have turned down the Flesh Tone setting. But, for the most part, I have not really changed much since I got it.

Lee Bailey posted something about White Balance helping to curb some of the brightness, so I did tune that down just a little in the past week for night viewing, and I really like that (This set is really bright at night, even with the LED set at Minimum.)

Is this what you are talking about?

You are amazing...reading the manual and everything!

I have been promoting the lowering of brightness at nite sense the default brightness setting is for britely let factory showrooms.
By value of settings I was asking if for example you had the brightness set to 35 for PVR 1 over its interface do you also have it set to 35 for the PVR 2 over ite interface and also to 35 for the DVD player over it's interface since these values are set and saved separtly for each of the 3 interfaces to provide for differences in the outputs from the 3 different sources.
We will find the solution to your problem and I have to admit it is one of the harder problems I have worked on which gives me insomnia but this is what I like to do since before retirement I worked with digital displays on and off as a developer for over 35 years.

I have been promoting the lowering of brightness at nite sense the default brightness setting is for britely let factory showrooms.
By value of settings I was asking if for example you had the brightness set to 35 for PVR 1 over its interface do you also have it set to 35 for the PVR 2 over ite interface and also to 35 for the DVD player over it's interface since these values are set and saved separtly for each of the 3 interfaces to provide for differences in the outputs from the 3 different sources.
We will find the solution to your problem and I have to admit it is one of the harder problems I have worked on which gives me insomnia but this is what I like to do since before retirement I worked with digital displays on and off as a developer for over 35 years.


I need to get you a Starbuck's gift certificate!

In answer to your question, the Brightness is set at 45 in Standard and Movie modes. I just now tried 35, but the blacks are too "blobby." On Standard, the default Contrast is 95, and that is where I have it...the default Color Gamut is Normal. On Movie, the default Contrast is 90, and that is also where I have it...the default Color Mode on Movie is sRGB, which is where I have it.

The LED setting allows for some lessening of brightness, and, as I have posted, Lee Bailey's suggestion of White Balance also helps with that. (Although Lee Bailey is one who will go into the Service Menu and also does some calibrating with some equipment that he has...I am way too chicken to go into the Service Menu, even though another member was kind enough to send me the manual, so I just adjust with the regular User Menu.)

I have used the Digital Video Essentials disc, and have found that the default settings are pretty good on this set...unless I do not know what I am doing, LOL!

You still do not seem to understant that if you make changes to any of the color sendings when watching content form PVR 1 that these are not the same settings that are used when watching content from PVR2 unless you reset them to the same values when watching content from PVR2. Again I state that the Picture color settings are set and saved separatly for each physical interface connection. And in addition the Picture size settings are set and saved separatly for each resolution received over each interface connection.
PS: I have never even been in a Starbucks or had any desire to be in one. I have 2 cups of coffee when I get up in the morning and have no desire for any the rest of the day.

You still do not seem to understant that if you make changes to any of the color sendings when watching content form PVR 1 that these are not the same settings that are used when watching content from PVR2 unless you reset them to the same values when watching content from PVR2. Again I state that the Picture color settings are set and saved separatly for each physical interface connection. And in addition the Picture size settings are set and saved separatly for each resolution received over each interface connection.
PS: I have never even been in a Starbucks or had any desire to be in one. I have 2 cups of coffee when I get up in the morning and have no desire for any the rest of the day.

If you are referring to each input having the ability to save different settings, I do understand that. But, I have them all set the same. I notice that when I play a DVD, depending on the DVD, some settings are grayed out, so, to some degree, on that one, the set has a "mind of its own." But, they are all the same, since I am pretty happy with the settings. The DVD is on HDMI2; the older Comcast box (3412) is on HDMI3, and the new Comcast box is on HDMI1. But, I have the same settings for each of those inputs. Is this what you mean?

Last night when it happened, I did the experiment that you suggested with the DVD, but it did not clear it up. Then I disconnected the DVD and connected each of the Comcast boxes separately, but to no avail. The picture without the power conditioner, with the Comcast boxes, was actually slightly worse. With the DVD, it was not worse, but not better either. I tried this with three different power strips w/surge protectors on them.

When I got the 750, Comcast came over and hooked up all of my components. Before that, the cable coax (the "antenna" cord...I think it is called coax, right?), went from the wall jack, into the power conditioner, and out to the box from there, and I had not had this problem. But, when they came out to hook things up with the new TV, they skipped that step with the coax, and went straight to the box from the wall. The tech manager is now saying that there may be a "grounding problem," his words.

They are coming out today to put it back the way it was. Worth a shot, I guess.

As far as Starbuck's...you are not missing much, imo. It is pretty overrated, but there is always one that is convenient for meeting up with people.

Yes you understand the settings correctly. I am just surprised that the DVD player and your cable boxes appear to be outputting the same brighness, contrast, tint etc levels so that the some settings need to be altered.
It is certainly possible that the power conditioner was being used to insure that the cable line and the power line had a solid ground connection between them especially if the TVs were being fed off of power strips. I will be interested in the results.
However the question of why the problem is time of day dependent when it occurs is still left unknown unless you are always recording some programs at night using one of the PVR boxes.

Yes you understand the settings correctly. I am just surprised that the DVD player and your cable boxes appear to be outputting the same brighness, contrast, tint etc levels so that the some settings need to be altered.
It is certainly possible that the power conditioner was being used to insure that the cable line and the power line had a solid ground connection between them especially if the TVs were being fed off of power strips. I will be interested in the results.
However the question of why the problem is time of day dependent when it occurs is still left unknown unless you are always recording some programs at night using one of the PVR boxes.

Hi, walford,

The problem did not occur last night, but I will need a week of that to believe that the problem is resolved. As I have posted to you earlier in this thread, there have been nights of relief, and then the next night it starts again.

As far as the settings, I used the Digital Video Essentials disc to obtain them. I realize that those settings would mainly pertain to the DVD player. (Also, I just do not watch DVDs that often.) However, I also used the HDNet program for my cable settings and they came out the same as the DVE disc. So, either I am not using those tools properly, or, based on the lighting in my condo...lots of daylight...they are about right. This will make my fellow owners on the 750 thread crazy, maybe, but I am happy with them, insofar as my lay eyes are concerned, and just do not feel a need to play around with them.

As long as the settings you have appear to be fine for both daytime and night time viewing then that is fine.
Has the cable connection through the power conditioner been changed?

As long as the settings you have appear to be fine for both daytime and night time viewing then that is fine.
Has the cable connection through the power conditioner been changed?

Yes, they hooked it back up through the power conditioner yesterday. They also changed the last remaining splitter, because my electrician said to do that before he begins troubleshooting, just to be sure that it could be eliminated as the problem. I also changed all of the surge protection strips on my TVs that, unlike the 750, do not have power conditioners. All done yesterday afternoon.

I probably should also do the settings at nighttime, but I just have not gotten around to it. All of the settings were done during the day, with the LED set at Auto. That would probably change at night, though I do not think that that is the problem, since I had a month with the 750 before the problem began, and all of my other TVs never had the problem before and have the same settings that they have had for years.

So, tomorrow, I will let you know if we get through another night without problems. Fingers crossed...

Again, you have been just wonderful!

I look forward to getting your report tomorrow. If there is no problem I beleive I have a possible explanation for the problem.

You said you are using dimmer switches. Some models of dimmer switches throw out a lot of interference. Try with all dimmer switches completely off.

You said you are using dimmer switches. Some models of dimmer switches throw out a lot of interference. Try with all dimmer switches completely off.

Hi, k_ross,

The lights have been set that way for three or four years. Do you think that it would change all of a sudden?

Thank you for your input!



walford,

If it happens tonight, I am going to look forward to your new thoughts, too!

I had a similar problem with my reception with comcast basic and qam. I always happened when all the free loaders hooked up to watch their favorite shows. Picture went grainy (snowy like) like in an analog over the air broadcast.

Solved the problem by cancelling the tv service use the ota hd feeds now.

Well, well, well...two nights in a row without the problem. Maybe something we did the day before yesterday helped. Keeping my fingers crossed that it does not occur tonight. This is the first time since it started that it has gone two nights without happening.

walford, if it is not occurring after American Idol tonight, I am going to do the settings when it is dark. Since having the two Comcast boxes is temporary, I may have to use Standard for day and Movie for night, if they come out differently. I will let you know tomorrow what the result is.

To everyone trying to help me: Thank you so very much!

Sorry I am late in responding today.
I had a theory that maybe the problem was not time of day related but outside temperature related, however, the fact that playing of DVDs also have the problem with cable disconnected did not fit that theory when combinded with exxtension chord experiment.
Next time you have the problem I suggest unpluging the Power conditioner from the wall since from you have said that will turn off the 750 tv and all of the equipment associatedd with it. If the problem is still occuring on the other 3 TVs then at lease we can elimante any of the 750 equipment from being the cause.

Sorry I am late in responding today.
I had a theory that maybe the problem was not time of day related but outside temperature related, however, the fact that playing of DVDs also have the problem with cable disconnected did not fit that theory when combinded with exxtension chord experiment.
Next time you have the problem I suggest unpluging the Power conditioner from the wall since from you have said that will turn off the 750 tv and all of the equipment associatedd with it. If the problem is still occuring on the other 3 TVs then at lease we can elimante any of the 750 equipment from being the cause.


Gaah! It happened again tonight. Not sure which has me more irritated...having it start up again, or having my crush, who is half my age, and maybe gay, lose American Idol!

At least coming here and getting your assistance helps. I have done what you suggested, and the problem is still happening with the other TVs. The Comcast techs are suggesting a reconfiguration of the cable wiring inside my apartment. It is not the least expensive option (but maybe not terribly so...have to ask my electrician), but if I do it the way that they are suggesting, it will reduce the number of splitters to one (which will be easily accessible) and eliminate the need for the amplifier.

One interesting thing that I just noticed when I did your experiment is: The TV that is on its own line from the splitter is in a room that is hardly used. So, unlike the other three, I turn the cable box off when it is not in use. When I went to check it just now, I turned the TV on first, before the box. It is a Sharp Aquos LCD. Before I turned the cable box on, when the TV was on with just a blank screen and the backlight, I could see the "interference" before there was even a picture. I knew, before I even turned the box on, that the picture was not going to be good...and it was not. Do you think this means anything? It is sort of making me think that rewiring the cable coax may not be an answer.

My electrician says his first step would be to check grounding (a concept that I still cannot grasp, despite the number of times that I have heard about it lately.)

Do you have any more thoughts?

Based on the DVD test, the extension chord test, and your findings of last night I do not believe that the problem is a comcast cable problem.
The interference is coming over the power line and may be over the ground wire. Your electrician should be able to temporarily install a ground isolation filter/transformer on one of the TVs.
We still have no idea what the actual source is and I expect that it is external to your unit but is effecting the power line to your unit from the power distribution location feeeding your units. Is the electrician aware of the extension chord test?

"Cord" ;)

Based on the DVD test, the extension chord test, and your findings of last night I do not believe that the problem is a comcast cable problem.
The interference is coming over the power line and may be over the ground wire. Your electrician should be able to temporarily install a ground isolation filter/transformer on one of the TVs.
We still have no idea what the actual source is and I expect that it is external to your unit but is effecting the power line to your unit from the power distribution location feeeding your units. Is the electrician aware of the extension chord test?

Yes, I told him about the extension cord test. He said that he is going to come over Tuesday and do some checks and go from there. He is going to see if the filters that you are talking about will work. So, I will let you know what he says after Tuesday afternoon. "Talk" with you then...and, as always, thank you.

The interference may not be coming over the ground conention it may be coming over the regular voltage connection. It appears to me that it may be caused by RF radiation from some nearby unit in your building. I remember as a boy that my Ham radio transmitter caused interference to my neighbors TV sets. I have no seen any reports of wireless routers or cell phones causing interference so I don't think one of them could be the cause. You might actually be able to get the FCC to check for RF interference.

The interference may not be coming over the ground conention it may be coming over the regular voltage connection. It appears to me that it may be caused by RF radiation from some nearby unit in your building. I remember as a boy that my Ham radio transmitter caused interference to my neighbors TV sets. I have no seen any reports of wireless routers or cell phones causing interference so I don't think one of them could be the cause. You might actually be able to get the FCC to check for RF interference.

Hi, walford,

Per your suggestion, I called the FCC. I only talked with a "front line" person who took the information and said that someone would be getting back to me.

Yesterday, my electrician was here. He checked the wires in my panel and said that a number of them were looser than they should be, but the grounding readings were within normal range. He tightened everything up and last night I did not have the problem. In fact, all of the pictures were improved. But, as you know, this thing can happen even after a night or two of not happening, so we will have to see. He also switched the surge protector that the amplifier was connected to, but, for some reason, I do not think that was an issue, since this was happening even when there was not an amplifier.

If you have any other thoughts, you know that they are appreciated!

Very interesting since the tightness of electrical fittings can be temperature dependent. Is the temperature of the panel's location change due to changes in the outside temperature?
I suggest that you turn on the Sharp Acquos with all input connections disconnected so that all you have is the backlighting. Then if you confirm that when the problem occurs if it also occurs on the Acquos backlit screeen that the problem is coming over the power line.if
Your power company also may be able to install some test equipment to determine the cause of the problem is RF or some otherthing else.

Very interesting since the tightness of electrical fittings can be temperature dependent. Is the temperature of the panel's location change due to changes in the outside temperature?
I suggest that you turn on the Sharp Acquos with all input connections disconnected so that all you have is the backlighting. Then if you confirm that when the problem occurs if it also occurs on the Acquos backlit screeen that the problem is coming over the power line.if
Your power company also may be able to install some test equipment to determine the cause of the problem is RF or some otherthing else.

We have had some wild temperature fluctuations...sometimes as much as 20 degrees one way or the other from one day to the next. And, I have had my windows open, then I feel cold, so I turn on the heat...then I get too warm and open the windows again. The panel is in a place in the condo that is probably the least subjected to either vents or windows, but, overall, I would say that, at this time of the year, I do change up the "climate control" inside the condo a lot. And, yes, I could have been changing it a lot when the problem began. I have not had this problem before, but my electrician said that the panels should be checked every three to five years, and it has been about four.

I will definitely try the Aquos experiment!

Thank you!

Many people have experienced TV signal problems with antenna connections in the summer since the connections expand in the heat and therefore can cause problems. Once tightened down in the summer they never experience the same problem again.
We may have finally found the problem I will keep my fingers crossed.
It might also make sense to have the electricrtcian tighten all of the wall plug wire connections.

Many people have experienced TV signal problems with antenna connections in the summer since the connections expand in the heat and therefore can cause problems. Once tightened down in the summer they never experience the same problem again.
We may have finally found the problem I will keep my fingers crossed.
It might also make sense to have the electricrtcian tighten all of the wall plug wire connections.

Back to the drawing board...it happened again last night. I will ask the electrician to check the wall plug wires, but he will have to come back, so I do not know when he can fit me in again. He did ask me to ask my power company to check the wires up to and into the meter, so I am waiting for them to do that. I am just trying not to cry from frustration right now...no waterproof mascara!

Were you able to run the Aquous experiment last night when it happened?

Any new news.
Where is your power meter located?
I beleive that the power company get put a monitoring device on your power to check for power problems. Since the problem happens both on your DLP TV and on your LCD TVs it appears that the power may be having very minor interuptions which are not enough to cause any problems with electrical devices in your home.
When the problem is resolved please post the cause and solution.

Any new news.
Where is your power meter located?
I beleive that the power company get put a monitoring device on your power to check for power problems. Since the problem happens both on your DLP TV and on your LCD TVs it appears that the power may be having very minor interuptions which are not enough to cause any problems with electrical devices in your home.
When the problem is resolved please post the cause and solution.

I still have not heard back from the power company. We tried something new yesterday: The line from the drop goes into a jack behind the Murphy bed in my second bedroom. When I moved in, Comcast hooked up a really long coax to make sure that there was enough to go to the first three-way splitter and the bed was built after that. The space between the wall and the bed with its attached bookcases was very small. We thought that there was a chance that the coax was being squeezed. There were also some extension cords that were plugged into outlets that were also located behind the bed. We could not even get the extension cords out because the ends would not fit through the space.

So, we actually cut the cords, drilled some holes in the bed where they would not be noticeable and ran new coax and electrical cords through the holes where they have plenty of room to "breathe." The electrical cords were done Friday when my handyman was here to cut the holes in the bed. That seemed to help some, since there were only a couple of short-lived instances of the problem after that. The coax was done yesterday when Comcast was here, and, so far, no occurrence of the problem...but we have seen it happen just when it appears to have been cleared up, so we shall see.

The hole drilling was actually my electrician's idea.

Are the coax and the extension cords right next to each other or do they go through separate holes to keep them apart?
Is there any possible relationship between the problem and the temperature in the second bedroom or with electrical equipment plugged into the extension cords operating?

Are the coax and the extension cords right next to each other or do they go through separate holes to keep them apart?
Is there any possible relationship between the problem and the temperature in the second bedroom or with electrical equipment plugged into the extension cords operating?

They are in the same hole, but there is plenty of room. They were all bunched behind the bed for four years before with no problem, so I did not think about separate holes...neither did Comcast or my electrician. The only electrical cord that is going through it now is a really, really thick one that goes to a Monster brand surge protector. It looks very well "insulated" if that is the word for it. As far as the temperature in the second bedroom, it is usually the same as the rest of the condo. There is rarely a temperature fluctuation in different rooms in the condo, at least that I have noticed.

Did I answer what you were asking?

What I am worried about is either the extrension cord or the coax radiating an RF signal that is being picked up by the other. This can happen if they run parrallel to each other for any distance with very little separation between them. However, I stil have no explanation for the apparent time of day on some days dependency.

Interference from adjacent condos/apts.
Light dimmer that is "old".
Baby monitors
fluorescent lights (including CFLs)
Stray RFI/EMI radiating from contractor work bleeding into cable feed.

There can be many possibilities.

Interference from adjacent condos/apts.
Light dimmer that is "old".
Baby monitors
fluorescent lights (including CFLs)
Stray RFI/EMI radiating from contractor work bleeding into cable feed.

There can be many possibilities.


I have 11 lamps with dimmers on them, but they are not all on the same circuit breaker. So, could they affect all four TVs if they are not on the same circuit breaker?

No baby monitors or CFLs. My kitchen cabinets have Xenon under cabinet lamps, but they are more like halogen than fluorescent, at least in terms of the appearance of the light output and the fact that they can be dimmed.

What are RFI/EMI?

What I am worried about is either the extrension cord or the coax radiating an RF signal that is being picked up by the other. This can happen if they run parrallel to each other for any distance with very little separation between them. However, I stil have no explanation for the apparent time of day on some days dependency.


What is weird is that now the problem is happening in the day and not the night. We are having a particularly cool day in Denver and I noticed that when I had my heater on, it started happening, but when I turned it back down, it stopped. Coincidence? I am not sure, since I have not really paid attention to that as a pattern. I will have to pay closer attention to that to see if there is a correlation.

It has been getting better, though.

You had mentioned that you like to sleep with your windows open and that you turn up the heat to compensate on cold nights. This would probably mean that the distripution panel locastion and the second bedroom are warmer then normal since they do not have open windows.
Where is the electric power meter for your unit located? I assume it is in the hall or is possibly in an outside location available to the meter reader.

You had mentioned that you like to sleep with your windows open and that you turn up the heat to compensate on cold nights. This would probably mean that the distripution panel locastion and the second bedroom are warmer then normal since they do not have open windows.
Where is the electric power meter for your unit located? I assume it is in the hall or is possibly in an outside location available to the meter reader.

It is located in a special room in the garage (about four floors down) where all of the other units' meters are located. They are in attached groups of about 20. Per my electrician's suggestion, I have called to have the wires feeding the meter checked, but they said it will take 30 to 60 days to get to it, as it is considered lower priority and there are lots of meter check calls in the queue.

Actually, the windows in the second bedroom are usually open, to get good cross-ventilation, since I am in a corner unit and I really love "airing out" the unit this time of year.

Do you think that I should call the HVAC guys?

How is the temperature in the garage controlled in the winter?
I don't think the HVAC guys will help. Is there anyway you can rerun the extension cord test? Since it supplied power that bypassed your power meter and all of your intenal power panel distribuiton and provided interference free TV it is certainly a clue to the source of the problem.

What are RFI/EMI?

Radio Frequency Interference
Electro Magnetic Interference


Easy test...
Check TV's that there is no interference.
Turn up the themostat to start the heater and see if the interference occurs.
Turn down thermostat. Wait for heater to shutdown. See if interference stops.

Try it a few times to verify a consistent pattern.

And yes, dimmers could cause interference, even on different circuits.
Another easy test...
With the heat Off.... ;)
Turn off all dimmer switches. Verify the TV's have no interference.
Turn on one dimmer switch and dim by half. Check for interference.
Do this test for each dimmer switch one at a time. See if one (or two) causes a problem.

How is the temperature in the garage controlled in the winter?
I don't think the HVAC guys will help. Is there anyway you can rerun the extension cord test? Since it supplied power that bypassed your power meter and all of your intenal power panel distribuiton and provided interference free TV it is certainly a clue to the source of the problem.

Yes, I can re-run it, but first I have to get a long enough extension cord. It has not been happening for as long a period when it has happened lately, so I have to have one here, rather than wait for the Comcast guys to get here.

The garage is heated. It does not have AC in the summer, but stays relatively cool as it does have fans.

Thank you, walford!!

Radio Frequency Interference
Electro Magnetic Interference


Easy test...
Check TV's that there is no interference.
Turn up the themostat to start the heater and see if the interference occurs.
Turn down thermostat. Wait for heater to shutdown. See if interference stops.

Try it a few times to verify a consistent pattern.

And yes, dimmers could cause interference, even on different circuits.
Another easy test...
With the heat Off.... ;)
Turn off all dimmer switches. Verify the TV's have no interference.
Turn on one dimmer switch and dim by half. Check for interference.
Do this test for each dimmer switch one at a time. See if one (or two) causes a problem.

Okay, I am going to try those suggestions, too. Thank you so much!

Some thoughts:
Interference on the power line would cross all ciircuts from your power distraibution box, there are not filters for each cirtuit breaker.
Have you made any chages to the electronic equipment in your home, such as additions to your PC, Installation of a new wireless router or phone system, or use of bluetooth devices?

Just two cents worth. I have Comcast, in a town just south of Boston. I am having similar problems. Comcast is putting my computer modem on some sort computer monitored program at their office along with some of the others on my street that are having problems,. I am having a tv/computer problem like the dude here. They suspect it might be cross contamination from the electric company on an outside pole bleeding into their system, in part due to a bad storm a few weeks ago. Just a thought,

Some thoughts:
Interference on the power line would cross all ciircuts from your power distraibution box, there are not filters for each cirtuit breaker.
Have you made any chages to the electronic equipment in your home, such as additions to your PC, Installation of a new wireless router or phone system, or use of bluetooth devices?


Hi, walford and Ratman,

The problem is still occurring, but less frequently. About a year ago, they put all the power lines outside of our building under ground. Or, are you talking about inside my condo? If it is the latter, I think that I may have found a source, or a symptom of the source: Whenever my under cabinet lights in the kitchen are on (and they are on a dimmer) for a prolonged period of time, which is typical for me at night, the problem can occur.

When my electrician was here, he said that the dimmer needs a "workout," meaning moving the brightness control up and down, to maintain it properly. But, I did not know that and have not been doing it for the last four years. Ratman may be right that it needs to be replaced. He is probably going to do that and check the circuit that it is on. That is the one area of the electrical that he did not do during the remodel as it was in an area that did not get remodeled. My electrician said that that circuit is the one that feeds the area with the drop and the amp.

Also, I moved the electrical cord that was running through the bookcase holes with the cable coax. So now, the coax is completely separated from any electrical cords. The only things running through those holes now is the coax and the telephone line cord to the base unit.

So, that is the latest update.

Just two cents worth. I have Comcast, in a town just south of Boston. I am having similar problems. Comcast is putting my computer modem on some sort computer monitored program at their office along with some of the others on my street that are having problems,. I am having a tv/computer problem like the dude here. They suspect it might be cross contamination from the electric company on an outside pole bleeding into their system, in part due to a bad storm a few weeks ago. Just a thought,

Hi, Kvn653,

If the problem is outside your home, you are lucky. My neighbors are not having the problem, so I am afraid that I am having to troubleshoot within my condo. Also, I am not having computer or phone issues, and both are with Comcast.

Hope they find your issue soon! (Don't forget to ask for credits on your bill...I received some pretty healthy ones through this process!)

Whenever my under cabinet lights in the kitchen are on (and they are on a dimmer) for a prolonged period of time, which is typical for me at night, the problem can occur.

When my electrician was here, he said that the dimmer needs a "workout," meaning moving the brightness control up and down, to maintain it properly.

Makes sense...
When lowering the brightness, the dimmer itself will generate heat (especially if you have a lot of lights on the same dimmer), which not only will fail after years of usage, but is also a potential fire hazard.

Depending on the type if dimmer, the "workout" could be effective temporarily. With a "new" dimmer, it may be a good idea to "exercise" the switch instead of a "workout".;)

IMO, considering the age of the switch and usage, for $5 or $10, get a new switch. Spend the extra few bucks and get a heavy duty dimmer (for longevity and peace of mind).

Good luck and hope you found the source of your problem.

Makes sense...
When lowering the brightness, the dimmer itself will generate heat (especially if you have a lot of lights on the same dimmer), which not only will fail after years of usage, but is also a potential fire hazard.

Depending on the type if dimmer, the "workout" could be effective temporarily. With a "new" dimmer, it may be a good idea to "exercise" the switch instead of a "workout".;)

IMO, considering the age of the switch and usage, for $5 or $10, get a new switch. Spend the extra few bucks and get a heavy duty dimmer (for longevity and peace of mind).

Good luck and hope you found the source of your problem.

Actually, I think I was using "workout" in the way that you are using "exercise." The problem is that I have not been exercising it and now it just may be ruined. It is a the type of dimmer that looks like a wall mounted light switch. It is a "heavier" duty one, but I just did not know to maintain it.

There are a number of under cabinet lights on it. They are the Xenon type. Pat, my electrician, will probably change it for me and check the circuit.

Thanks so much for your help!

Actually, I think I was using "workout" in the way that you are using "exercise."
That was an attempt a humor.

I think you have found the cause of the problem. I was not aware that dimmers could cause interference RF problems based on age and/ or heat generated and it also did not dawn on me that when you tried turning off all the circuit breakers to find the problem in one of your early tests that that did not include the one that includes the drop and amp.

That was an attempt a humor.

*slaps forehead!*

I think you have found the cause of the problem. I was not aware that dimmers could cause interference RF problems based on age and/ or heat generated and it also did not dawn on me that when you tried turning off all the circuit breakers to find the problem in one of your early tests that that did not include the one that includes the drop and amp.

Oh, please, please, I hope that you are right! I am so tired of this.

Well if the temperature in the kitchen went up more then normal when the heat came on on cold nights then every symtom and test can be explained. In any case turn off the dimmer for the ktchen lights and consider getting a low wattage motion detecting night light that just plugs into a wall socket. I have one in my kitchen and it works just great.

... or test the heater/thermostat to verify/elimimate as the cause (as suggested earlier). "Temperature" is probably not the cause per se.

As for the dimmer in the kitchen, maybe he will need to use the dimmer and watch TV when a "night light" won't provide enough light.

And to stress... if the existing dimmer is starting to die, it's best to replace with a new one rated for the amount of lights it's servicing. A dimmer switch (expecially a failing one) generates heat.

And last but not least... put the TV and A/V gear on a "dedicated" circuit for better isolation.

Hopefully the electrician will identify, isolate and resolve the sporadic interference.