topic Why both LMBs in Sky Q

Why both LMBs

Stuart3394 — Wed, 11 Dec 2024 10:43:15 GMT

Im completely confused. I moved the woring of my sky box and reconnected after a while and i couldnt get much of a signal. Whats confuses me is if i connected LMB 1 i get channel 2 and 4 perfectly and nothing more so thought it was a wire problem and handt terminated cables right or something. Then i tried LMB 2 and i got something like channel 1 and 7 perfectrly so i presume the same. I had understood that each LMB went to a differnt tuner and two tuners were necessary to record and play at the same time. Because of the aforehand i called sky - coming next week. Then i decided to coneect bith LMB1 and LMB 2 wire at the same time and it works perfect with channel 1.2.3.4.5.6.7...................all working perfectly. Why is this? See,s nothing to do with view or record? My next step is to do box text further down the cable route since there is a splitter etc.. Any clues apprecaited

Re: Why both LMBs

TimmyBGood — Wed, 11 Dec 2024 10:51:54 GMT

@Stuart3394

Is this Sky+ or Sky Q? There's a fundamental difference in how the two platforms use the LNB (Low Noise Block downconverter)

Re: Why both LMBs

Stuart3394 — Wed, 11 Dec 2024 11:29:54 GMT

I have Sky Q

Re: Why both LMBs

oldfella — Wed, 11 Dec 2024 11:51:43 GMT

Hi @Stuart3394

The Sky Q LNB has two cables.

One is for horizontal polarisation and one for vertical polarisation.

Using only one cable will only give you half the available channels.

Re: Why both LMBs

Stuart3394 — Wed, 11 Dec 2024 12:35:08 GMT

"half available channels"

I can understand that a little but thats not quite what happened...Connecting LMB1 only gave eg 2,4 ONLY, connecting LMB2 only gave eg 1, 7 ONLY; connecting LMB1+2 gave me 1,2,3,4,5,6,7,8,9......................................aka all channels

Re: Why both LMBs

nigea99 — Wed, 11 Dec 2024 13:36:04 GMT

@Stuart3394 wrote:

"half available channels"

I can understand that a little but thats not quite what happened...Connecting LMB1 only gave eg 2,4 ONLY, connecting LMB2 only gave eg 1, 7 ONLY; connecting LMB1+2 gave me 1,2,3,4,5,6,7,8,9......................................aka all channels

hi @Stuart3394

I can't think of any reason why a single cable connected would result in a significant loss of channels (below the approx half as mentioned)

As @oldfella says the different cables used by Q carry approx half the channels as one is used for the Horizontal polarised transponders & the other the vertical. Being a wideband feed, all frequencies used should be available (unlike the older Universal LNBs which are split by low & high bands)

Thus if you are getting some channels you should get all channels using that polarity unless there is a dish alignement issue - but the latter is disproved by comment stating you get them when both cables are connected

Don't forget that channels in the guide are not ordered by either polarisation or frequency

Re: Why both LMBs

nigea99 — Wed, 11 Dec 2024 13:26:43 GMT

@Stuart3394

Can I just double check that you have your own dish with the twin cables & you aren't fed by a communal system with wall points labelled Sat1 & Sat2

If you do have the latter then the behaviour is still not as expected and more likely to be a power supply issue to the electronics in the system

Re: Why both LMBs

Stuart3394 — Wed, 11 Dec 2024 13:45:10 GMT

yes my own dish and the wires im using are coming direct from the LMB (no distributors in the way). Previously i 'diagnosed' using the wonder sky help which ended with an engineers apointment. Now im thinking its working so not worth it. But probably since its 'weird' i will let them come to offer inspiration