# D11-100 + MythTV PVR-150 help please



## ndorf (Feb 5, 2009)

If anyone can help shed some light on this problem:

SETUP: DirecTV, standard def. I built a MythTV setup on a P4 2.8Ghz mobo and have 1Gb Ram, 100Gb Hard Drive (less than half full), a PVR-150 LP (low profile), an Nvidia based GeForce 5xxx card. My first reciever was the old Hughes GAEBOA Director pack, and I recently picked up a D11-100 and activitated it. So now I have Myth controlling the D11 via usb-to-serial connection instead of an IR blinker on the Hughes. The recording profile is MPEG2-PS @ 720x480 which is pretty standard.

PROBLEM: on some channels, I get terrible pixelation, chirping, blocking, whatever you want to call it. The lower channels <100 which include locals are not a problem. Mostly the channels in the 200-300 range, which include TNT, TBS, and many more I like to watch. It almost seems like the problems are on alternating channels but that doesn't always hold to be true. The problem existed with the Hughes stb setup and continues with the newer D11.

I have had a DTV technician out to install an new LNB and run new RG6 cabling and connectors from the dish to the junction at the side of my house where my home coax connects up. He also provided new cabling in the room (farthest side of the house from the dish) where this STB is.

The problem exists but is not as prominent when I test just using the STB and bypassing the mythtv box. I used to have a splitter between the dish and the junction box but the DTV tech removed it to eliminate if that was the problem (it was not). I have also tried using a Channel Master inline power amplifier (takes power from the STB) specifically designed for DBS bands and it helps the signal strength but does not eliminate the problem. My signals are all in the mid 80's to 90's on Sat A so we agreed no problem with trees or other dish interference.

Here's the perplexing part. When another computer (a high end gaming system) is turned on elsewhere in the house, the problem persists (and it's unfortunately on all the time for reasons I can't get into), and when it is turned off my reception improves. Also as I progressively turn on more lights in the room where the stb is, the signal gets worse (pixelation); when I start shutting off the lights it gets better.

When I plug the STB into an entirely different outlet I have no problem. Unfortunately that requires an extension cord across the room and is not practical. So I bought a line-interactive UPS system and plugged the STB into that. Helped just a little but still disappointing results.

Then I bought RF Ferrite Chokes and put them on the power cord to the Mythtv box, the STB, and the offending PC power cord in the other room (which I found is on the same power circuit.) 

Still no satisfaction, just very minor incremental improvements.

So I'm trying to figure out whether I have an issue with not enough watts or amps getting into the STB, or is it an overwhelming amount of Electromagnetic or Radio Interference. The switching on / off of the lights in the room creating havoc is a give-way, but I can't tell if it's because of line noise or power. Either way with my UPS system I would have though I have clean power.

Help? Anyone? The Wife Acceptance Factor has lately dipped more drastically than the S&P 500 

Thanks


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## carl6 (Nov 16, 2005)

The fact that you can correct the problem by powering the stb from a different outlet syas that you have an electrical problem of some sort. My suspicion is that the outlet you are running out of has the hot and neutral reversed and does not have a proper ground. It could be something else. Regardless, you need to get an electrician involved, as the situation is not only a nuisance trying to watch/record TV, but is potentially a critical safety or fire hazard.


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## ndorf (Feb 5, 2009)

Carl,

Thanks for your reply. Your advice made perfect sense. The next thing I did was to buy one of those $5 testers from Home Depot that has the three lights which will indicate if there is any kind of problem with an outlet including polarity. You just plug it in and then observe which of the three lights turn on. Well, the outlet checked out fine, not polarity reversal.

Then I purchased a Kill-a-Watt to satisfy my curiosity on current and wattage utilization. What I found is that the D11-100 draws .16 Amps and 12 Watts on the stations that have the pixelation issue and .18 Amps and 14 Watts when tuned to the station that have no problems.

When I put the Kill-a-Watt on the MythTV box I found that it draws about 1.3Amps and 100 Watts...this did not vary much according to whether I was using the pause live tv function (taxes the hard drive) or not.

Then I measured the consumption of the other "offending" PC in the other room and it draws between 1.4 and 2 Amps depending upon the activity--closer to 2 Amps when running a video-intensive game.

Then I put the Kill-A-Watt back on the STB and determined that the current and wattage draw remained constant regardless of whether the gaming PC was on or off.

Now I'm not so sure I have a power problem...doesn't this now sound like some sort of interference-related issue?


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## BattleZone (Nov 13, 2007)

You could still have a ground loop or current on your ground line from a different outlet. There is definitely a power issue, which is proven by the fact that plugging in to a different outlet/circuit fixes the problem. These issues are rarely easy to find, and as previously recommended, you REALLY need to get an electrician involved.


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## carl6 (Nov 16, 2005)

The minor difference in power draw on the channels that show the problem might be related to the transponder polarization involved (the receiver sends a 13V signal for odd transponders, or right hand circular polarization, and an 18V signal for even transponders, or left hand circular polarization). If in fact your problem is only happening when you are trying to select even transponders, then it is possibly a voltage drop problem between the receiver and the dish (on the coax line). I'm just speculating here, but that is the only thing that comes to mind when I try to think of why the receiver would draw more power when the symptoms appear than when they don't.


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## Igor (Jan 3, 2005)

carl6 said:


> The minor difference in power draw on the channels that show the problem might be related to the transponder polarization involved (the receiver sends a 13V signal for odd transponders, or right hand circular polarization, and an 18V signal for even transponders, or left hand circular polarization). If in fact your problem is only happening when you are trying to select even transponders, then it is possibly a voltage drop problem between the receiver and the dish (on the coax line). I'm just speculating here, but that is the only thing that comes to mind when I try to think of why the receiver would draw more power when the symptoms appear than when they don't.


If this installation has a ground loop issue, the voltage at the LNB may be slightly higher. For example 13V may be arriving at 14V and 18V at 19V. If this is the case, the 14V may cause pixelation because the LNB is toggling left and right polarization. This is likely to be a grounding issue.


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## ndorf (Feb 5, 2009)

I took my Volt OhmMeter and put one probe in the ground on the outlet and touched the other lead to the jacket of the Coax going into the STB. Zero Ohms, suggesting that there is a common ground, right?

OK, all suggestions appreciated. Time to call an electrician.


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## ndorf (Feb 5, 2009)

Yet more information. Unplugged the PC's 3 prong plug and inserted a 3 prong to 2 prong adapter just temporarily to see if it would make the problem go away. (I realize this is not per code and it was just for a 2 minute test.) It did not make any difference, which came as a surprise. Removed the adapter and normally plugged in again. I guess this is sounding more like RFI?


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