Missing channels DVB-S

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AnotherDummy

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#283941 22-Mar-2021 04:00

Hi, I’m after some troubleshooting help.
Recently bought a house, came with satellite dish.
Bought a DishTv satellite decoder. We’re missing TVNZ channels and a bunch of others.
Receiving breeze, bravo and a couple others with no quality issues (finding something like 4 tv and 5 radio channels or vice-versa)
Have tried factory reset and all manner of scanning options found under the menu.
What should I be looking for/trying?
There are no markings on the dish or LNB so I don’t have a clue what the specs are for anything.
The place is in Diamond Harbour, christchurch if that makes any difference.
Appreciate any advice! Thanks.

Rikkitic

Awrrr
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#2678176 22-Mar-2021 08:59

Channels are broadcast in bundles called muxes. Each mux operates at a different frequency. You are missing the TV NZ mux which contains the channels you can't receive. It is possible that your LNB is faulty though I can't say for sure. It is also possible that there could be a problem in the cable connection that is only affecting the TV NZ frequency. Or maybe your receiver just isn't tuning all the frequencies for some reason. The fact that you are receiving some channels suggests there is no problem with the dish or TV. There are people here more knowledgeable than me who may be able to suggest some diagnostic steps. Otherwise I would try eliminating things one by one to pinpoint the problem. If possible try borrowing another receiver to see if that works. Run a temporary cable directly to the dish if you can. Replace the LNB (they are not hugely expensive).

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fe31nz

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#2678888 23-Mar-2021 00:38

This can happen if you put in the wrong local oscillator frequency settings for the LNB. I can just happen that one multiplex is on a frequency that will tune with the wrong settings. You need to know what sort of LNB it is. Is it a Sky dish? If so, then the most likely setting is 10750 for the lower local oscillator, and there is only one LO so you set the switch frequency to the maximum value that the field will accept and the second LO frequency then does not matter - set it to the same as the lower LO frequency. Other settings you might need:

Modulation system: DVB-S (not DVB-S2)

Symbol rate: 22500

FEC: 3/4

Polarity: Horizontal

Tone: Off

You should then be able to tune two Freeview frequencies:

12456000 (Mediaworks and miscellaneous)

12483000 (TVNZ and Maori TV)

and also the Sky frequency where they broadcast their free-to-air DVB-S channels such as Prime:

12519000

It looks like you are currently only getting the 12456000 frequency - check that it says that is the frequency it is receiving. If it gives you a different number, then the LO frequency is wrong.

The way the LO works is that the frequency generated by the LO is mixed (heterodyned) with the incoming signal in the LNB and that results in two signals at incoming+LO and incoming-LO. A filter then blocks all the higher frequencies including the incoming frequencies leaving only the incoming-LO signal. The LO frequency is chosen so that mixing it with the incoming signal will result in the incoming-LO frequencies being in the range that the tuner in your receiver operates on, which are dramatically lower that the frequency of the incoming signal and are easy to receive with standard electronics. Trying to receive the incoming frequencies directly is impossible with normal electronics.

So if your receiver is receiving one frequency with the Mediaworks channels on it, and it is not on 12456000, then the difference between the reported frequency and 12456000 is the difference between the LO value you are using and the correct LO value.

Rikkitic

Awrrr
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#2679013 23-Mar-2021 09:40

fe31nz:

This can happen if you put in the wrong local oscillator frequency settings for the LNB.

This is good advice. I didn't know you could still receive anything if the LO was wrong. LNBs are usually either 10750 or 10300. Just trying changing one to the other to see if it makes a difference.

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Oblivian

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#2679033 23-Mar-2021 10:13

*11300

Rikkitic

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#2679036 23-Mar-2021 10:18

Oblivian:

*11300

Thanks. Typo. I make a lot these days.

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AnotherDummy

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#2679481 23-Mar-2021 19:25

Thanks very much for this, I won’t be out there until the weekend but very keen to try some things out! Much appreciated. Will post an update once I’ve investigated further.

Dyson

Shop now for Dyson appliances (affiliate link).

AnotherDummy

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#2705469 10-May-2021 12:59

Hey, just thought I'd post an update since I was back on here.

Checked all the parameters suggested and ended up replacing the LNB ourselves (had also ordered a new bracket as we suspected this was an older sky dish).

Worked a treat, just lined it up as close as possible to what the previous one had been and we were away :-)

Thanks for the advice.