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Post Info TOPIC: Failed LNB's...


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Failed LNB's...


Hi all;

       Ok time for a bit of a gripe.... But first a bit of background history. Sorry to bore you. 

I've installed television antennas for over 30 odd years now and started of in Melbourne before SBS moved to the UHF band. As well  as a electronics teck repairing anything with a 3 pin plug on the end of it. Besides the work shop duty i could also put my had to PA's systems and Video surveillance, pay tv MATV both big and small and also i also have a amateur licence ( full call ) so I've been around a while !!! Been there, done that !!!

Now the wife and my self like to travel and for the last 8 odd years have in joyed the life style that traveling this big country has to offer. The wife isn't to bothered but i like to watch a little television and only travel with a satilight dish and vast decoder, been that way for ages. Tryed a few free to air antennas in the early years but gave way to satilight.

So over the last couple of years I've had to replace the LNB on my dish, I'm on my third one now and didn't check it be fore we left for Tassie. Normally i have a s/h austar dish on roof of my house just for the vast decoder in the caravan, this allows for any up dates etc. As for when we travel we travel with a 80cm dish and tripod. Good quality coax cable, connectors and a good satilight meter. The coax is stored ( rolled ) in the front boot of the caravan, As for the dish/LMB that is transported on top of our double bed and never moves while we travel. while @ home the dish/LNB are stored in front of the caravan and under cover and out of the weather. If a LNB is meant to stay out side and in all types of weather.

So on this trip check the decoder, yep all good. Go and set the system up in Tassie and  no good . Have 13 Volts @ the end of the coax were it connects to the LMB.  compass reading ( spot on ) elevation and skew  also spot on . I've only done this a couple of hundred times before. I do not have a spare LMB ( bad mistake ) , but will have to wait till we are in Hobart and will get a couple more LMB's , cheap insurance @ about $25 each.

My question is why the failure and this would be aimed at the brain trust, why am i the only one ( and this frustrating ) that has problems. When i first started with satilight television for the caravan, i started off with a s/h austar dish and LNB and this worked fine up till i traveled north and had a few problems, tured out that a 80 cm dish was the answer. 

Over the course of a few years the Austar LMB failed. This was replaced with a Aerial industries LNB and then when that failed that one was replaced with a Satking LNB this one was bought on our last trip over to Tassie in August 2015 and now it looks like it also has failed. So when I it Hobart in a couple of days time, guess what I'm going to buy !!!

OK so over to the brain trust, and thanks

 



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Steven we experienced the same problem on our 6 months trip in 2013. First failure at Cunnamulla where local techie diagnosed fault to LNB. New unit problem solved. About a month later at Winton same again and new LNB worked fine and no more problems for trip.

 On returning home still puzzled I refitted the original unit and it worked fine, so tried the second unit and it also worked fine. I still have no idea why we had problems with reception but the original LNB is still working so now have two spares.

Can only think it may have been a satelite problem, but really don't know. I would be interested if you also found your old units now also work by switching them when everything is set up and working and the only change is the LNB.

Alan



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Possibly bad connection ?

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Guru

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installed sat tv for around 15 years, only ever seen 2 dead lnbs, most were faulty connectors. replaced a lot more as it was a genuine fault code we got paid for. My first guess would be alinement, then fittings.
cheers
blaze

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Graeme  our connections were done to death before we went into Cunnamulla  with the whole kit and caboodle. the local techies diagnosis was faulty LNB. Took the lot back to campsite , fitted new LNB with the original cables etc. and worked fine. Second time left everything setup went into Winton bought new LMB, returned to camp changed LMB and hey presto signal. Still don't know what the problem was.



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Yea had the same . Was correct frequency setting right ? I guess it was registered ? Lol

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Just a thought on the Failing lnb when holidaying in some remote areas especially in summer a person would focus their satellite dish usually to optus C1 Sat which resides around 156deg not far from north when peaking for best signal don't forget that not only are the radio signals focused on the LNB but also a concentration of Summer heat is reflected off the Heat absorbing Matt black Dish which could lead to temperatures  exceeding Lnb Tolerance Standard cheap Lnb usually has a Temperature Rating of -40c-+60c before catastrophic damage better quality higher temp rating I have been outback with a 90cm dish and measured after noon with IR thermometer temps in excess of 75c at dish face, anyhow just a thought and also I am not looking for any arguments or disputations or peoples life stories, I just offer this as a possible reason as to WHY 



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The amount of times we set up camp . To find a tree across the road is stopping the signal ! At Broom camping ground it was a steel street light . Moved 300mm ., perfect signal !! Mind is auto so no issues finding signal if everything else is ok .

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Guru

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The amount of times we set up camp . To find a tree across the road is stopping the signal ! At Broom camping ground it was a steel street light . Moved 300mm ., perfect signal !! Mind is auto so no issues finding signal if everything else is ok .

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Guru

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I am not an Electrician

On my manual sat dish set up, my meter (wife saver) box, is connected to the LNB
This is before any connections to the TV end of the cables

If no signal then it means
LNB problems
Satellite problems
Tree, in line of sight
Overcast, or water in the atmosphere blocking the signal

If signal at LNB but no TV, then it means
Cable connections
Sat box
TV had been left on DVD mode

There may be other problems that I am not aware of



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Tony

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For those people who experience Lnb Not working then replace Lnb working then fit original Lnb and working again, next time it plays up throw a bucket of water over the Lnb and dish and  see if that works after cooling down, as for using the Satellite Meter to determine that the Lnb is ok is not 100% proof that the unit is ok inside the Lnb there is Low noise amplifier, local oscillator mixer and final amplifier which mixes with a signal from satellite to give appropriate frequency output to produce a picture on tv, all those separate modules within the Low Noise Block Downconvertor (LNB)are affected and tend to drift with heat resulting with no sig at tv   



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pinballpat wrote:

For those people who experience Lnb Not working then replace Lnb working then fit original Lnb and working again, next time it plays up throw a bucket of water over the Lnb and dish and  see if that works after cooling down, as for using the Satellite Meter to determine that the Lnb is ok is not 100% proof that the unit is ok inside the Lnb there is Low noise amplifier, local oscillator mixer and final amplifier which mixes with a signal from satellite to give appropriate frequency output to produce a picture on tv, all those separate modules within the Low Noise Block Downconvertor (LNB)are affected and tend to drift with heat resulting with no sig at tv   


 Thanks for this info pinballpat, is there any way of determining if a LNB is faulty, with just normal Grey Nomad traveling tools



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Tony

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With the normal G/Nomad setup There isn't anything a Satellite Meter which is as Broad as a Barn door and will let anything through and peak the meter without good quality test equipment hard to tell what is coming out of LNB but with your Receiver in test mode and on correct transponder you should see a peak in strength and Quality, I only responded to one of the posts which explained that his LNB died and he replaced it and all well then tried the original and it worked my only explanation for that is that the LNB overheated when I set my system up I always look for a shady spot with a clear view to the North hope this helps the guy with the "Lazarus" LNB which keeps getting raised from the dead



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Thanks for that info pinballpat, as I was unaware that heat would affect the LNB

I normally set my dish up, so that the shade of the dish covers the lower fridge vent

The fridge vent mostly faces to the east, so that in the afternoon sun, the sat dish would be shaded by the campervan

I shall remember your trick of cooling the LNB down, if I have TV, and someone else in that camp, does not



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Tony

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Hi guy's /brain trust;

                               Well to day we drove into Hobart and picked up a new LMB, $19.00 so all good. Any way will i was waiting to get served, i got talking to another  antenna teck  and was talking to him about things in general ( shop talk ) and after only being able to buy only one new LMB, the other teck gave me a couple of s/h LMB's 

So the afternoon was spent playing with the dish and LNB. It did turn out that my original LNB had indeed failed and the main cause of my greif. As for the second hand LNB's, one was ok and the other one was also faulty, so one goes into the bin and the second one will be used as a spare. But when i get back home in a few weeks i will get another new LNB

The new one is connected and works fine.  So maybe some think of and some think else to carry in the spare's box. So lessons learnt !!!

 

So thanks every one for the reply's and comments.



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