LNB/Cable fault? wtf?

alan767

I have a dish thats only 6 months old and I lost all satellite channels several weeks ago.

I got hold of a Horizon USB DSM which has a LNB/Cable test feature.

I've run this test with the meter connected to the dish and connected to other cable from the dish coming to the box at the TV.

It fails everytime.

Can a LNB this new really and suddenly fail for no reason?

banie01

alan767 wrote: »

I have a dish thats only 6 months old and I lost all satellite channels several weeks ago.

I got hold of a Horizon USB DSM which has a LNB/Cable test feature.

I've run this test with the meter connected to the dish and connected to other cable from the dish coming to the box at the TV.

It fails everytime.

Can a LNB this new really and suddenly fail for no reason?

Yes....
While LNB's are a generally reliable piece of kit.
Any electronic item is subject to the possibility of manufacturing defects or sudden unexplained component failure.
But it would be rare.
Have you tried testing a known working LNB to see if the test feature of the meter gives the correct result on that?
Are you testing the LNB at the dish? Or are you testing at the receiver end of the cable?
Testing at the dish with a patch cable direct from the LNB to the meter will rule out a cable fault and let you know if it is the LNB.
Testing at receiver still leaves the possibility that your cabling is at fault and the LNB could be fine.

alan767

Hi banieo1,

Great minds think alike lol as I have tested a working LNB next door which passes and I tested with meter connected directly to LNB and then indoors with receiver is.

Where does the LNB draw its power from?

Is it from the receiver box?

Thanks

alan767

Doh I've just found out that the LNB does in fact draw its power form the receiver through the co-ax.

This posslbly explains the test result. I'll have to get up of the roof and run it again to verify.

The Cush

alan767 wrote: »

I've just found out that the LNB does in fact draw its power form the receiver through the co-ax.

Basic LNB info here - https://en.wikipedia.org/wiki/Low-noise_block_downconverter#Universal_LNB_.28.22Astra.22_LNB.29

Peter Rhea

alan767 wrote: »

Doh I've just found out that the LNB does in fact draw its power form the receiver through the co-ax.

This posslbly explains the test result.

How would it explain the test result?

alan767

The Cush wrote: »

Basic LNB info here - https://en.wikipedia.org/wiki/Low-noise_block_downconverter#Universal_LNB_.28.22Astra.22_LNB.29

Good info there thanks!

alan767

Peter Rhea wrote: »

How would it explain the test result?

Hi Peter,
I didn't have the receiver connected initially. Does the LNB draw power from the meter if the receiver is not connected?

alan767

Update: Some positive progress has been made lads

I now have the receiver connected and it will remain so.

I went back up and connected the meter to a different output from the LNB and the LNB/Cable test passes ok.

There are 4 outputs in total from this LNB [but only one in use for the receiver atm] so it would seem we have identified a faulty output.

The meter indicated that it found the satellite and the 2nd bar appeared [Q]below the top one but after a couple of seconds it seems to loose it again?

Any thoughts?

thanks

Peter Rhea

alan767 wrote: »

Does the LNB draw power from the meter if the receiver is not connected?

Yes, provided you haven't set 'LNB voltage' to 'off'. ('LNB 0V' would appear on the display.)

alan767 wrote: »

The meter indicated that it found the satellite and the 2nd bar appeared below the top one but after a couple of seconds it seems to loose it again?

If you can't see any obvious damage & you have made decent connections & you're not doing something daft like moving in front of the dish & blocking the signal, I would be inclined to just try a replacement lnb.

alan767

OK I made some slight adjustments and got the Q value to 100% so tightened all bolts. Ran a scan but the receiver still does not find any channels? It seems I will have to switch the receiver cable to the known good output I had the meter connected to.

I was under the impression that if I had the dish aligned with the meter that all working outputs would be ok?

Is it however standard procedure to connect the receiver to the output that you had the meter connected to when aligning the dish?

Thanks

Peter Rhea

It shouldn't matter which output you connect to.

If it does make a difference, you either have a faulty output or your connections aren't good enough & swapping outputs is just giving the impression of curing the problem, when all you've really done is temporarily make the bad connection functional, simply by moving the connector in relation to the cable.

alan767

My connections are always exemplary so thats ruled out. Ok success at last it turned out that the coax connector from receiver to LNB was actually broken due to a combination of being tightened too much [ by the original installer] and possibly the strong wind.

Hence the reason why that output was showing a fault on the meter.

I replaced the connector and switched to another output. Ran scan - All channels back.

The outputs seem to be corroding from exposure to rain etc and one outermost output no longer works at all now possibly for this reason.

Should I try to cover these in some way to protect them from the elements?

Thanks for your help lads! Much appreciated

The Cush

alan767 wrote: »

Should I try to cover these in some way to protect them from the elements?

I always use amalgamating tape e.g. http://www.tvtrade.ie/10m-self-amalgamating-tape.html.

You could also use LNB rubber boots e.g. http://www.satcure.co.uk/accs/page1a.htm#boot

Info here - http://www.satcure.co.uk/tech/boots.htm

alan767

Great links Cush thanks!

Cantona's Collars

Found the problem.

Liameter

You should always protect the copper wires with grease:
http://www.satcure.co.uk/tech/fconn.htm