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Any way to tell if your LNB is bad?


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19 replies to this topic

#1 OFFLINE   slice1900

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Posted 13 March 2013 - 04:30 PM

I recently upgraded my system that had a WB68 and WB616 to use two SWM-16s, and had the dish aligned as well. The run from the dish is only about 30' and is RG6 solid copper. Signal strength is excellent, 90s across the board on 99c, 103ca and 103cb, as is SWM signal strength. There are no trees or any other obstruction, and today was a clear day without much wind.

Most channels are fine, but certain channels, like NFLHD for example, will occasionally break up and pixellate. I saw it on some other channels like BTNHD so it isn't just that one channel either. This happens on multiple receivers, but other channels like ESPNHD and ESPN2HD are fine. I have never had problems with those, before or since I had the dish aligned and upgraded the switches.

I used to see this happen regularly before on those same channels, but my signal strength was lower due to my dish being a bit out of alignment so I assumed getting that fixed would be the end of these problems but I guess I was wrong!

I looked online and found that NFLHD is on D12 103W (103ca) transponder 18. I checked that one directly and see it varying between 93 and 94 when I watched it for several minutes (but unfortunately didn't catch it when the channel was pixellating) I also found a sun outage calculator, and put in D12/103W for the satellite, and clicked on my location (leaving everything else at default) and the last day of sun outages for me should have been a week ago.

Since everything else has been fixed/replaced in my system aside from the LNB, I'm wondering if it may be the issue? Could it cause this type of problem? Is there any way to tell if it is bad, or should I just have it replaced and hope it helps?

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#2 OFFLINE   samrs

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Posted 13 March 2013 - 04:47 PM

Your H20's are old. When they were new there were pixelization issues.

Swap the LNB.

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#3 OFFLINE   damondlt

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Posted 13 March 2013 - 06:34 PM

Bad LNB's Usually have ODD EVEN issues.

Low signals on the odd or even but not both.

I'm going to Guess its your H20's.
But a replacement LNB isn't very much. So you could try that, Never hurts to have a Spare!

 

 

 


#4 OFFLINE   HoTat2

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Posted 13 March 2013 - 07:20 PM

Bad LNB's Usually have ODD EVEN issues.

Low signals on the odd or even but not both.

I'm going to Guess its your H20's.
But a replacement LNB isn't very much. So you could try that, Never hurts to have a Spare!


The high-low patterns are usually caused by a bad cable of the four from a four output LNB, so it could still be a bad LNB itself.

#5 OFFLINE   slice1900

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Posted 13 March 2013 - 09:34 PM

I saw the problems today on two H20s and an H24 - the other receivers were tuned to different channels like ESPN or CNN which have never exhibited these problems for me. Tomorrow I'll put some of the other H24s along with some different H20s on the problem channels and see if the problems recur, but I think the fact I am now seeing and always have seen this type of event on both version of receiver pretty much rules out pointing the finger at the H20s. Not saying they've been trouble free, over the years two stopped displaying via HDMI, one quit receiving OTA and one completely lost all 99 and 103 satellites (and of course there was the recall of a half dozen -600s five years ago) There have been no issues with any of them for probably three years, I think the weak ones have already been culled :)

I'll try to keep track of the channels I see the issues on and look them up in the transponder map to see if they are all even transponders. Today I saw the issues on NFLHD and BTNHD. Both are 103ca, transponders 18 and 14, respectively. When I looked through the list thinking about channels I have seen the problems on regularly in the recent past (but before I had the dish peaked and replaced the switches) they are ALL on D12 103ca, but some are even transponders and some are odd transponders.

Not one channel on 99W has ever given me problems. Is it possible that a bad LNB could exhibit problems not divided by even/odd transponders but by frequency? 103ca is Ka-hi, and 99c is Ka-lo. The Ka-hi on 99 are spot beams, and since I get my locals OTA I don't use 99s for anything as far as I know. I don't see any channels I ever use on 103cb, which uses Ka-hi. I'm going to try tuning a few of those 103cb channels tomorrow to see what happens, if I see problems there that would really point to it being a Ka-hi issue.

Unless there is some way to conclusively rule out an LNB problem I think the best course of action would be to get it replaced. I need the tech back soon anyway to get the dish and antenna grounded, so I can have him do that while he's up there.

Is it possible the dish not being grounded could be causing these issues? When I was googling a bit about grounding stuff last week I saw claims that grounding problems can cause pixellation issues. Is that true? If I am able to isolate it to Ka-hi, unless there's some reason why grounding problems would/could preferentially be an issue for Ka-hi, this doesn't seem too likely but I thought I'd ask.

#6 OFFLINE   carl6

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Posted 13 March 2013 - 10:57 PM

If you do isolate the problem to specific locations, the next step would be to swap a receiver from one of your good locations to one of your problem locations. That would allow you to determine if it is the location or the receiver. If it is the location, it could be coax, connectors, the particular SWM output you are using, etc.

It is worth noting that your problems do appear to isolate to one of the four lines from the LNB. Another test would be to swap the lines at the input to the SWMs.

Are your SWMs paralleled through splitters, or is one of them running off the legacy outputs of the other one? Which SWM, and which output from that SWM, are your problems on? Are all the effected receivers on the same SWM/output?

#7 OFFLINE   slice1900

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Posted 14 March 2013 - 12:42 AM

The SWMs are split, with the proper diode steering splitters and cables are run to the same input on each SWM-16, etc. Two of the three receivers today were on one SWM-16, the third on the other. Cables are QS RG6 solid copper with compression ends throughout.

These problems have been present for some time, but were part of a larger set of issues I began troubleshooting about a month ago because they had recently become noticeably worse. Between getting my dish aligned and replacing the jumpers between splitters and switches I've fixed a couple things I was able to prove were part of the problem. I'm not sure if the legacy switches were a problem but I figure I needed to upgrade to SWM someday and getting rid of the old switches eliminated those as a variable. But there is still something yet to be fixed.

I'm certain the problem isn't traceable to a particular set of receivers or cables. At one time or another over the past months I've seen issues on these same channels on pretty much every receiver. The only reason I saw the problem only three receivers today is because those are the only ones tuned to one of the channels I keep having issues with. All my receivers or cables can't be bad, the problem has to lie closer to the dish.

I had previously tried swapping the LNB cables around but that was before I'd fixed the other issues so I'll give that another try and swap 13v no tone with 18v tone and 18v no tone with 13v tone so each one swaps both satellite and polarity. I doubt it will matter but it's worth a shot. I'm also going to tune a bunch of receivers to channels on 103ca, and also try a few of the 103cb channels, after making a note of which satellite/transponder the channel is on. I want to see if I can catch it "in the act" and check the signal from that transponder. I checked signal strength today while it was happening and had 90s across the board, but maybe it is doing something weird where it dips low and back up again too quickly for the slow updating signal strength screen that shows all transponders at once to catch.

I hope tomorrow won't be one of those days when everything is working perfectly, just to frustrate my debugging...

#8 OFFLINE   HoTat2

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Posted 14 March 2013 - 01:33 AM

... Not one channel on 99W has ever given me problems. Is it possible that a bad LNB could exhibit problems not divided by even/odd transponders but by frequency? 103ca is Ka-hi, and 99c is Ka-lo. The Ka-hi on 99 are spot beams, and since I get my locals OTA I don't use 99s for anything as far as I know. I don't see any channels I ever use on 103cb, which uses Ka-hi. I'm going to try tuning a few of those 103cb channels tomorrow to see what happens, if I see problems there that would really point to it being a Ka-hi issue.


To note, 103cb is actually Ka-lo band national beam transponders (D10).

#9 OFFLINE   slice1900

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Posted 14 March 2013 - 09:43 AM

To note, 103cb is actually Ka-lo band national beam transponders (D10).



Thanks for correcting me, I must have misread that in the TPN map yesterday. I will still try tuning a couple of 103cb channels, just to see if the problem is Ka-hi, or somehow related to the two 103 sats, but if my theory is correct and Ka-hi is my problem then when the 103ca channels start exhibiting issues the 103cb channels should remain solid.

It may be cloudy today so I might not see any issues. For some reason I've noticed in the past that it tends to happen more on sunny days, which confused me before since I had originally assumed the problem was related to signal strength and I should have the best signal on a clear day. Perhaps the sun heating up the dish/LNB makes whatever issue I'm having more likely?

#10 OFFLINE   davring

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Posted 14 March 2013 - 10:14 AM

I just this morning had my LNB replaced as it lost all even transponders on 103S, 103CA and 103CB, about 4 in the afternoon. To confirm it was temperature sensitive i sprayed it with the garden hose for a couple of minutes and it returned to normal. I had one fail the same way about six years ago.
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#11 OFFLINE   damondlt

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Posted 14 March 2013 - 10:48 AM

I just this morning had my LNB replaced as it lost all even transponders on 103S, 103CA and 103CB, about 4 in the afternoon. To confirm it was temperature sensitive i sprayed it with the garden hose for a couple of minutes and it returned to normal. I had one fail the same way about six years ago.

Are you sure its wasn't the connections on the LNB?

Or did they just replace LNB?

 

 

 


#12 OFFLINE   damondlt

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Posted 14 March 2013 - 10:53 AM

I just this morning had my LNB replaced as it lost all even transponders on 103S, 103CA and 103CB, about 4 in the afternoon. .

Its sounds like LNB issue.
Like someone stated sure loose wire , may cause Odd EVEN issue, But most likly its LNBF, or switch.

 

 

 


#13 OFFLINE   davring

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Posted 14 March 2013 - 11:18 AM

Are you sure its wasn't the connections on the LNB?

Or did they just replace LNB?


Because the issue was affecting both of my HR's it had to be either the WB68 or the LNB. Before I called, i verified all my connections. Cooling it down, confirmed my suspicions.
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#14 OFFLINE   damondlt

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Posted 14 March 2013 - 11:39 AM

Because the issue was affecting both of my HR's it had to be either the WB68 or the LNB. Before I called, i verified all my connections. Cooling it down, confirmed my suspicions.

:up:

 

 

 


#15 OFFLINE   slice1900

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Posted 14 March 2013 - 12:13 PM

Interesting. Not sure if I can get a hose to spray up high enough to hit my dish, but it might be worth trying.

#16 OFFLINE   samrs

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Posted 14 March 2013 - 12:53 PM

Some of those rocks some folks take with their whiskey and a plastic bag should do the trick.
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#17 OFFLINE   slice1900

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Posted 16 March 2013 - 02:10 PM

Happened again yesterday evening, with over a dozen receivers tuned to a channel on 103ca having the problem at the same time, forcing a switch to the SD channel on 101. For most of the afternoon, a few receivers were tuned to a couple channels on 103ca with no issues. That's how it always is, it works as it should for a while and then out of the blue the picture starts breaking up for no reason. Later in the evening when I checked the picture was rock solid once again.

This was after I swapped the cables so I can clearly rule out the four LNB cables/connectors, the receivers, cable runs to the receivers, and the new SWM switches/splitters.

I've already ordered the new LNB, it should arrive early next week, hopefully after it's installed the problem will go away, because I'll be out of things to fix or replace!

#18 OFFLINE   slice1900

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Posted 18 March 2013 - 01:08 PM

New LNB is arriving today and should get installed tomorrow, but I saw something interesting today. Previously I've checked signal strength and didn't see any problems, but I tried using the signal meters per a suggestion and can easily see why I have trouble.

When I check signal meters on transponders on 99c, it'll show say 93 and stay pretty steady, very rarely changing and if it does by only one up or down. When I do the same on 103ca or 103cb during a time when the picture is breaking up on the 103ca channels, I'd see say 94 then 87 then 90....it jumps around a lot. It also sometimes jumps to ZERO, then back up into the 80s or 90s. Easy to see why I'm having problems, but this is something that is the signal strength screen never showed me before.

If anyone suspects trouble with their LNB, use those signal meters, it may look very different!

#19 OFFLINE   slice1900

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Posted 19 March 2013 - 01:08 PM

LNB was replaced early this morning, so far so good. My installer liked that the new one was Eagle Aspen, he feels it is the best. The old one was a WNC. Signals were a tiny bit stronger after replacement on a few transponders, but that may be down to random chance. I couldn't see any visible signs of damage or cracking on the LNB covers. There does appear to be a slight seam on the top of the 99/101/103 cover, but that may be normal.

I notice that when I tip it from one side to the other I can hear something loose sliding from one end to the other of the whole assembly, that doesn't seem right! Sounds like a screw came out, or maybe some piece of surface mounted electronics like an electrolytic capacitor broke loose? If the new one is problem free for a week or two so I'm assured this LNB is definitely bad, I may try prying it open to see what that loose thing is out of curiousity before trashing it. :)

#20 OFFLINE   slice1900

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Posted 01 April 2013 - 02:20 PM

Quick update so anyone searching this thread later will know that it was a bad LNB and replacing it fixed the problem. All channels are rock solid now all the time, on 103ca and everywhere else.

Before I tossed it, I tried to take apart the old LNB to see what was rattling around inside it. Unfortunately I didn't have whatever bit was needed to remove the back plate, nor do I own a sawzall.




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