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7 posts

Wannabe Geek


  Reply # 561497 26-Dec-2011 09:43
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The Voltage readings on the LNB Input were
DC 18.86 - 19v
AC 40.7

And for comparison
Loop Out
DC 18.03
AC 38.9

So the the LNB Input is 1 volt higher than it should be, but is that enough to damage the LNB??

1574 posts

Uber Geek
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  Reply # 561510 26-Dec-2011 10:45
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None of those voltage readings would be likely to be the problem.

As per grolschie's reply, I suddenly realised that you might not have understood what 'off-skew' meant.
I apologize if I am explaining something that you already understand and have checked.

The LNB skew is rotational alignment in relation to the LNB holder. i.e. If you turn (or are able to turn) the LNB around in its holder, it will affect the signal strength because the Horizontal and Vertical polarities are defined positions. Turning the LNB away from optimum polarity position will weaken the signal because the LNB polarities will not line up with the signal polarities bouncing off the satellite.

Granted, this issue would have almost certainly have been picked up by your installer, if indeed it was the cause. So it's unlikely to be the cause, but it would be good to check it off the list of possible things.

Regarding how to check if your LNB has the correct skew, that's hard to say because not all LNBs are the same and each would have it's proper positioning according to its specs.
What type of LNB and dish do you have?

Another possible cause could be if there are any splitters or 'in-line' amplifiers on the cable between the LNB and the receiver?
These could be deteriorating and causing issues.



7 posts

Wannabe Geek


  Reply # 561526 26-Dec-2011 12:34
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Thanks Dontpanic42 for your continued interest in the post.

As far as LNB skew, I have to trust that the installer did the right thing up top. I intend to call him tonight and will ask about the details of the LNB and dish.

There isn’t any splitter but there are a couple of joins in the cable that the installer noted cause some reduction in the signal strength.  However I don’t think they are the cause of my problem. At the last visit by the installer, after replacing the LNB the SBS signal strength went up from just over 60 to 76%. And a few days later and literally from one day to another it dropped back to around  62-64% and no one had messed with the cabling.

256 posts

Ultimate Geek
+1 received by user: 3


  Reply # 561573 26-Dec-2011 17:03
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jkbrennan: Thanks Dontpanic42 for your continued interest in the post.

As far as LNB skew, I have to trust that the installer did the right thing up top. I intend to call him tonight and will ask about the details of the LNB and dish.

There isn’t any splitter but there are a couple of joins in the cable that the installer noted cause some reduction in the signal strength.  However I don’t think they are the cause of my problem. At the last visit by the installer, after replacing the LNB the SBS signal strength went up from just over 60 to 76%. And a few days later and literally from one day to another it dropped back to around  62-64% and no one had messed with the cabling.



SBS has been down in power for a while now 




 

1929 posts

Uber Geek
+1 received by user: 129


  Reply # 561599 26-Dec-2011 18:43
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As the LNBs keep deteriorating after install, which is normal due to aging components, then surely the logical answer is to replace the co-ax with new high quality co-ax and install a larger dish. Obviously the decoder is OK as it produces a signal as soon as the strength reaches a certain level which in your case seems to be only with a brand new LNB. Bigger dish = more gain therefore increased signal strength. I was under the impression that a 1m dish is considered suitable for SBS and a 65cm (Sky) dish is barely adequate?

256 posts

Ultimate Geek
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  Reply # 561605 26-Dec-2011 19:15
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jkbrennan: , after replacing the LNB the SBS signal strength went up from just over 60 to 76%. And a few days later and literally from one day to another it dropped back to around  62-64% and no one had messed with the cabling.




The power levels have been up and down lately on SBS, which might coincide with your signal problems, levels were down last time i looked so possibly has nothing to do with faulty LNB and more like the dish being too small, 16000 installs sounds like a Sky tech




 

256 posts

Ultimate Geek
+1 received by user: 3


  Reply # 561607 26-Dec-2011 19:20
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what brand LNB is it and what are the input frequencies ? Should be written on the LNB




 



7 posts

Wannabe Geek


  Reply # 561641 26-Dec-2011 21:09
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Thanks guys for your input.

I didn’t manage to get through to the installer tonight, so no update on the type of LNB. It’s a very steep tiled roof, so can’t take a quick look. It is also a rental property, so was trying to avoid replacing the dish (already paid to replace the LNB).

“SBS signal down in power…”   umm Not sure if that can explain the behaviour as recorded above in regard to the time the installer replaced the LNB a few weeks ago.

Finally I’m off to the beach tomorrow so may not be checking in for a few days.

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