ELECTROPARTقیمت انواع مولتی سوئیچ آنتن مرکزی در الکتروپارت برای دریافت لیست قیمت , پیامک بزنید3893 866 936
How can we test and Maintenace LNC?
The only way to fully test an LNB is to fit it to a suitably aligned dish and connect a satellite receiver. Then check to make sure every channel is there. If no channels are missing and if it continues to work through a hot day and a cold night, the LNB is fine.
However, if some channels still appear to be missing (with a known good LNB), this could be the fault of the cable (bad connection, water ingress or kinked or wrong type), the receiver or the dish (distorted or misaligned) or local interference (DECT phone, car radar detector, etc.). So then you need to use a process of elimination by swapping the dish, the cable and the receiver (for a different make/model as some receivers won't work correctly with some LNBs). Note that some wall-plate connectors can also cause "channels missing" problems and some electronic devices (DECT 'phone base stations, "Snooper" type radar detectors and microwave ovens) can cause similar problems. I've even had it reported that a bad battery connection in a laptop computer wiped out some channels!
Can't I test it with a meter?
You can NOT test an LNB with a multimeter.
A cheap Satfinder meter is more useful but it simply looks at the average strength of all frequencies. It will not tell you if some frequencies are missing. An expensive meter looks at a specific frequency (sometimes more than one) but it will not tell you if some frequencies are missing.
Also, most meters rely on battery power. If the battery can not supply enough current to the LNB, it may give a false reading.
In short, you can not fully test an LNB with any meter but you can perform a partial test.
Faulty LNB? Could my LNB be damaged?
A "universal" LNB is designed to operate normally with an input voltage of up to 20 volts. At a somewhat higher voltage, you can expect the LNB to fail. The time taken to fail depends on the applied voltage and duration. It would take a highly unusual fault to cause a Digibox to provide more than 20 volts and any digibox that did so would almost certainly emit expensive smoke within seconds.
So it's simply not possible to "blow" an LNB with overvoltage. The receiver will always die first (and it's extremely rare).
The usual causes of "failure" are:-
1. Bad connection at the LNB.
2. Bad connection at the LNB.
3. Bad connection at the LNB.
4. Bad connection at the receiver.
The causes are:-
1. Incorrect F plug fitting.
2. Moisture ingress caused by incorrect weatherproofing and/or lack of silicone grease.
3. Using RG6, which has a steel core wire that has a very high resistance compared with copper AND is prone to rusting.
4. Using thin "shotgun" cable where the core wire is thin and doesn't create enough contact pressure.
There's also a possibility of cable damage, although it would usually be obvious that this was the cause (unless the installer is ignoring it and blaming the LNB for the fault, knowing that he'll make an LNB sale AND get called back).
The reason that LNB replacement often "cures" the fault is that it disturbs and cleans the bad connection, which returns a short time later as the connection goes bad again. So it's sensible to clean the connection and try again before replacing an LNB.
Is my LNB causing Grainy Pictures?
No.
Because the signals for digital channels are "multiplexed" together, the satellite TV receiver has to decode them and piece them back together. This means that neither the LNB nor the cable connecting it to the receiver can cause "noisy" or "grainy" pictures. Digital is an "all or nothing" system. You either see a perfect picture (as perfect as the original transmission) or else an extremely broken picture or no picture at all. There is no inbetween stage as there was with analogue. So, if you are seeing "grainy" pictures, the fault must lie in the receiver (rare) or the TV (rare) or in the cable connecting them together. It could be caused by interference in your house or it could simply be your imagination.
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