Satellite box problem

[Juswundrin]

Hi

Our satellite box (non-Sky) has started to act strangely, and I wondered if it's simply on the way out (it's almost six years old) or if the problem could be elsewhere (dish, LNB...)

When we switch on, BBC News is always OK and the BBCi streams are OK; all of the other channels (with, sometimes, the exception of whichever channel we'd been watching last the previous day) show as "No Signal".

After a time - from a few minutes to over half an hour - the channels come to life, usually spontaneously but once or twice with a period of 'static' interference (the type we sometimes get during a downpour of exceptionally heavy rain).

After that, it's fine. It's almost as if the box needs to 'warm up'.

I'd be grateful for any advice.

Thanks

[Northender]

When you say switch on , do you mean powering the Sat box up?

They are normally left switched on or in standby.

Having said that when you first switch on can you obtain a signal strength reading? (on a Sky box its under Services)

If you can , monitor it over the "warming up" period.

Could be a loose/bad conection at the LNB or Sat box , check the co-axial connections.

I once "pieced" out a lead with 50 ohm instead of 75 ohm , only a couple of metres , but the difference in signal strength was substantial.

[Juswundrin]

Hi

"When you say switch on , do you mean powering the Sat box up?"

Sorry, I meant turning on the TV, the box is always on standby.

"when you first switch on can you obtain a signal strength reading?"

During the initial period, it switches around something like 18%..46%..18%..46% (with the occasional 0% in there too)

"Could be a loose/bad conection at the LNB or Sat box , check the co-axial connections."

Thanks, I will check them out, but - and this is why I hesitated to use the term "warm up" - a bad connection would surely remain bad, there's no reason for it to improve after a few minutes?

Thanks again

[Northender]

The boxes do output a dc voltage (around 18v) I think on the co-axial to power the lnb , I'm not sure if this is switched off when the box is in standby.

If it is switched then that could explain why your signal is up and down during warm up.

[Martin963]

You could do a bit of detective work here.

If you've always got BBC News and the BBC streams it's just possible that your LNB and receiver are happy on vertical polaristion but not on horizontal.

You can check this very easily - can you get ch 4 + 1 but not ch 4 itself?   Or are both versions not working?

If you can get vertical but not horizontal transmissions it suggests that either the power supply in your box is dying or that the LNB has gone faulty.    I was called to a box (on Astra 1 for German fare) where the the output volts were a mere 2 V but that was enough to power the LNB for vertical polarisation,  but of course horizontal was quite impossible.

If however you can't get ANY ch 4 programmes,   or indeed other BBC channels at all,   then it's more likely that your dish has moved slightly from the optimum 2D orientation and is still working OK on 2B.   This may have been exacerbated by poor skew setting in the first place.

Report back if you'd be so good on ch 4 and ch 4 + 1 and we'll go from there,   unless others have any other thoughts of course.....?

[Juswundrin]

Hi Martin

"can you get ch 4 + 1 but not ch 4 itself? Or are both versions not working?"

Neither seems to have a stronger signal than the other, and they both seem to 'wake up' after more or less the same length of time.

"If however you can't get ANY ch 4 programmes, or indeed other BBC channels at all, then it's more likely that your dish has moved slightly from the optimum 2D orientation and is still working OK on 2B. "

So apart from BBCNews and the streams everything comes back to life at more or less the same time (would it complicate things if I mentioned that ITV3 seems to come back ahead of the rest?)

So the most likely cause, then, is simply that the dish has slipped off its alignment slightly?

Thanks again, much appreciated.

[Martin963]

Well it doesn't *sound* like a voltage problem then.

Is the signal strength  (or better still quality) steady on BBC News?   I ask because the values you gave for the other channels are jumping around an awful lot,  and with a dish that's off beam a bit it doesn't follow that the levels would jump to that extent,  one just expects them to be down.   So I'm a little puzzled   (you can tell I was hoping it was going to be a polarisation voltage problem can't you??!!).

To be honest I think it's time to try your box on someone else's working Astra 2 dish (if you can) and try someone else's box on your dish.  

Sorry I can't be more specific,   I'd be inclined to think dish orientation problems but I'm loath to say definitely because there's no point in shinning up a ladder until we're certain.

[Juswundrin]

Thanks again Martin

The signal is absolutely fine on BBC News, the streams and (hadn't realised because there's nothing actually broadcast at the moment, I don't think) Rockworld.tv.

All other channels have now gone ciompletely; which has made us realise... all of the channels which still work are on 27500, and we've downloaded some new channels on 27500 and they all work fine (both H and V channels).

And all of the channels which we've lost are on 22000.

Does that help?

[Martin963]

Pretty much suggests that it's your reception specifically of 2D causing the problem. 

You've noticed a piece of evidence that seems to confirm your other observations - Astra 2D frequency allocations are slightly closer together than the rest of the fleet,   and because of this the symbol rate is restricted to 22000 kbps - that's putting it simply but in essence it's correct.

Now it therefore seems likely that something minor has happened to your dish.  It probably has moved a smidge,  but it may also be that the skew of the LNB was never quite right.   Basically the LNB - viewed from in front of the dish - needs a twist clockwise of about 15 to 30 deg from its "natural symmetrical tidy " position  in order to favour 2D.   It's best done while observing the quality meter.  If your skew wasn't optimised for 2D  (home of most of the important FTA channels) and if the dish has then budged a bit you're probably suffering the consequences you've described.

I'd still try and engineer a swap of box and dish with a friend if you can to check,   but the fact that both H & V are working correctly but 2D with its 22000 kbps have gone does lead me to think that a dish movement problem is the most likely explanation.  Why it should improve after warm up I can't explain,   although signal levels do regularly vary on the satellites and it may be that you switch on at roughly the same time of day and this happens to co-incide with an approaching peak of output level on 2D - I just don't know.

You can see the symbol rate situation I've described here if you're so minded.

http://www.lyngsat.com/28east.html

with 2D transponders being about 15 MHz apart and 2A and 2B being about 19 MHz apart.

[HoneySuckleDreams]

sorry to jump in on this discussion.

We have a problem where we are missing certain channels. But I think it's the reverse to the OP 2D missing problem. I think we are having problems with the 2B signal, as we can get all the BBC channels, but are missing BBC Radio 1,2,3,4,4LW and sometimes the red button doesn't work. Looking at the lyngsat link you posted Martin963, it looks like the ones I am missing are on 2B, including some of the BBC streams.

Would this point to a Skew problem? I've tried turning the LNB to what I think is around 19degrees, but i'm not sure. Could this be a voltage problem as well. Is this easy to test at the LNB end (i have a voltmeter and ladder at the ready)?

regards

[Martin963]

When the BBC radio services (apart from R5) and BBC News 24 (as it was then) moved from 2D onto 2B a couple of years ago there was a storm of complaint,  both from Europe (which should have got a BETTER signal from 2B) and indeed from Britain.

It may indeed be that you're over-skewed!   No one at Astra will admit it,  but the polarity of 2D is skewed in relation to the other satellites co-located at 28.2 deg E.    So you may find that if you turn the LNB back towards the natural symmetrical position you improve the 2B signal.

Of course the other factor is that each satellite is at least 100 km from the next one even though they are "colocated".   Normally this makes no practical difference on a dish, but if a dish is set up poorly it may favour some of the cluster over the others.  The classic one is that dishes set up in the early days for 28.2 deg E had trouble with Eurobird a 28.5 deg E and a very very gentle nudge eastwards would solve the problem.

What size dish have you got?  Where you are a bigger dish often is necessary,  and the bigger the dish the better the focus and the more likely that a slight problem with orientation will upset reception of one sat in a cluster.

If your problems have appeared recently then it's likely the dish has shifted a tiny bit.   But give the skew idea a try as well,   being careful not to go too far to knock out your 2D reception (ie twist anticlockwise a little bit as viewed from the front of the dish,  in order to favour 2B over 2D).

Mark the positions so that you can get back to where you were if it doesn't work.

You can easily measure the voltage,  13V (+ve on the inner) for vertical pol,  18V for horizontal.

What's harder to measure is the 22 kHz switching tone and as that's only required to jump up above 11.7 GHz (BBC radio is on 11.954 GHz) it's just possible that either the LNB has started to fail to respond to the tone or that the sat box has stopped providing it.   Do you get ANY signal on 11.954 GHz or is it completely dead?  (Harder to measure on a Sly box,  have you got that or a bog standard?)

You can soon tell with the 22 kHz by looking at the Lyngsat list and seeing if you're getting any channels above 11.7 GHz,  eg S4C digidol....

[HoneySuckleDreams]

I will try some more investigation. We have friends in the village who get perfect reception, and they are only 400m away. I borrowed their box and have the same problem, so I will try my box on their system to remove the box as an issue. We have both 80cm dishes so it would either be an LNB issue, cable or direction. I think I will leave the voltage tests for when my brother visits. I'm more of a draggy, droppy, clicky pointy sort of person when it comes to electronics and stuff and he knows a bit more about that side of things. But hopefully, it will be just a skew/direction thing. (as an asside, i've NEVER managed to get classicfm radio, it is always "blocky", or whatever the audio equivalent of a blocky picture is)

I'll post back a solution for other forum members (if I find one!)

[Juswundrin]

Hi again Martin

We finally got a day warm enough to stand up a ladder with the house doors open, and played around with the dish.

Moving the dish around showed us that it had been aligned OK (we could get a worse, but not better, maximum signal strength). So we decided to buy a new box, and the new Humax arrived yesterday.

We set it up, and we now have an absolutely excellent signal strength / quality immediadely on startup, so clearly it was a problem of some sort with the box.

Many thanks again for your help.

[Martin963]

Glad you're sorted,  although ultimately I don't think I was of much help!!!!

[HoneySuckleDreams]

...thought I would report back.

Spent an afternoon with my bro trying to re-adjust the dish to get the optimum signal strength, but with no luck. Maximum we got was 75% strength, 60% quality, and still missing stations.

However...after the big storm at the weekend I'm now at 90% for both, and all missing channels are there..and for the 1st time in 5 years I can get ClassicFM by satellite. I'm of up the ladder tomorrow to tighten a few bolts.

Bizarre...every cloud etc....

[Martin963]

Very odd.    The storm couldn't have blown down a tree or a branch that was gradually growing into the path of the signal could it....?

Other than that I'm at something of a loss.....

[Pierre ZFP]

So, the wind didn't bring down a big tree in front of your dish by any chance? [:D]

 

[HoneySuckleDreams]

Nope. All trees present and correct.

However...today...strength 90%, quality 60%...missing channels.

[Théière]

I had a problem last year with signal strength and quality, turned out to be wasps nesting inside the LNB. Have you looked to see if water or bugs have got inside?