All posts by jb38
Below are all of jb38's postings, with the most recent are at the bottom of the page.
G Dixon: The 4 sockets fitted on the amplifier used on this aerial are of a "one way" input nature as far as DC voltage is concerned, meaning that no matter which socket you connect the power supply into on the amplifier the 12volts DC voltage from the power supply will "not" (or should not!) appear on any of the other three outputs, the only thing that will do is the boosted signal from the amplifier.
If the aerial you bought as a replacement is exactly the same model as the one you are using, then the problem is more inclined to be caused by something connected into one of the output feeds, like for instance a TV or PVR capable of supplying power via its aerial socket to operate such as a mast head amplifier, because if any are? and the facility is switched on, then this will feed voltage up the coax and into the amplifier in exactly the same way as from the power unit, something which could cause problems if (as would be expected) the voltages are at different levels.
Therefore try this test. Switch off the mains to the aerials power supply followed by connecting the 4 coax cables back into the amplifier, then disconnect the TV's or boxes coupled into the various outlet point locations in the rooms and switch the aerial amps power supply back on, if the power supplies LED is illuminated, this indicates that your wiring is OK.
The next stage is to reconnect each of the TV or boxes used in the various locations "one at a time", checking after connecting each of the devices that the indicator on the power supply is still illuminated, if its not, remove whatever you have just reconnected and move onto the next device until they are all coupled up, the device you have removed being the culprit, therefore check its set up menu and look for "antenna power" being mentioned, needless to say disabling this facility if its seen mentioned.
Further advice dependant on feedback.
PS. By the way, if your replacement aerial is exactly the same as the one presently used, its assumed that you have tried swapping the power units over?
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yvonne cooper: Without knowledge of which brand model of Freeview box you are referring to, however nomatter which brand it might happen to be, the symptoms as described are suggestive of its operating system having failed, the fact of you having said that its already been powered down and disconnected from the mains (the ultimate test) and yet it still does not respond to commands, in most cases (especially so in lower priced devices) being an indication that the device is beyond repair.
It wouldnt do any harm to try powering it down again, but leaving it disconnected from the mains for about an hour or so to let its components thoroughly cool down.
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Davy Graham: If you are referring to a Sky box? try disconnecting it from the mains for 20 seconds or so before reconnecting it again, if this doesnt resolve the issue, then water might have gained access into the "F" connector on your dish partially shorting out the band switching commands sent out by the box to the LNB, this seriously restricting what you can view, as of course will also be the case if the dish has moved slightly out of alignment.
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G Dixon: The best way to look at the problem is from the angle that the LED on the power unit will "only" go out (but see undermentioned) if a short circuit occurs on the 12 volts that's connected into the aerials amplifier.
Secondly, as the 12 volt power fed into the amplifier is contained "within" said amplifier, it is not, or should not, be present on any of the other sockets used to feed the amplified signal into the various locations its required, therefore if any short circuit should occur on any of these outputs the LED should not be affected in any way.
However, leaving this aside for the minute I would like to know the result of the following test, the reason for the request being that if any short circuit occurs on these Labgear power units (the ones generally supplied with these aerials) the LED turns red but not actually go out, therefore with the aid of a small piece of wire I would like you to try shorting out the "in" socket on the power unit, i.e: the one that runs to the aerial, the easiest way being by holding one end of the wire onto the threaded part of the "in" socket and touching the inner part of the socket with the other end, does the LED turn red or go out altogether?
By the way, the power unit will not be harmed in any way by this test, as its protected against being damaged by a short circuit.
Also, if all the sockets on the aerial amp are coupled up but with nothing being connected into any of the outlet points located in the various rooms, is the LED illuminated or not?
As far as you not having changed anything is concerned, if any of your devices have carried out an automatic update at some point, (mostly occurring in the early hours of the morning) then this can in some cases result in various settings being altered.
As before, further assistance dependant on content of reply.
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Phil S: Have you tried disconnecting the box from the mains for 20 seconds or so before reconnecting it again and allowing it to go through the usual searching for listings procedure? should though this not resolve the problem then it could be caused by water have gained access into the dishes LNB "F" connector and partially shorting out the band switching commands sent by the box to the LNB, this type of thing seriously restricting what you can view, as of course will also be the case if the dish has moved slightly out of alignment through having been blown by the wind, it only taking the merest fraction of movement to do this, the best way of knowing if this is applicable or not being to have a look at the signal check screen, both levels (strength / quality) being a minimum of 60% and with the quality never being under the strength, this indicating that the dish is slightly out of alignment.
However, more detailed advice can be supplied with knowledge of the type of Sky box being referred to, e.g: Standard, Sky+, or Sky+HD.
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G Dixon: In addition to that said in my earlier posting, once you have tried the power unit test referred to, couple the power unit into the aerial amplifier (on your spare aerial) using a short "F" connector jumper lead, then try shorting out each of the three outlet ports on the amplifier whilst observing the power units LED.
Needless to say, if the Megaboost system is operating OK, the LED should not be affected in any way by creating a short circuit across the output ports.
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G Dixon: Many thanks for the update, your findings indicating that the amplifier is indeed defective by allowing the 12 volts supplied by the power unit to appear on its output ports, whereas if working properly it should be isolated from them by only allowing the amplified signal to travel down to your various outlet point locations, the fact that its not, meaning that power is being fed into the aerial connector points in your rooms, likewise anything connected into them.
By the way, and although you may have already tried this, but as one of the four ports on your aerial amplifier is connected into the power unit, (whereby being "in-out") did you also try the short circuit test on the lead that comes from the TV socket on the power unit?, as in this case the DC isolator (a small ceramic capacitor) is located inside the power unit.
Although it probably will not make any difference to the situation, but as the lead from the power unit can be connected into any of the 4 ports located on the left of the actual "aerial input" port on the amp, (connected into the aerial elements) I would like you to check if the situation remains the same by changing the port being used by the power unit.
The reason for the request being, that I cant quite remember if the amplifier uses a single isolator capacitor to feed the amplified signal into all ports at the same time, or each port has its own isolated output, although I do believe its the former due to the "shorting the output" test being active on all three outlet ports, the fourth port obviously being used by the power supply.
I will say though, that if you have outlet plates or boxes fitted in any room that the Freeview signal is fed into and you were in any way electrically inclined, you could get over the problem by fitting a small ceramic capacitor inside each outlet plate or box to block the 12 volts, the coax middle core being loosened off and the capacitor being fitted in series between the middle core and the point it was just removed from.
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Abbey: Good news then!!, pleased to see that you have managed to resolve the magic eyes I.O. port problem.
Thanks for the updating us on this.
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Wednesday 28 January 2015 9:26PM
Alan: In addition to that said by Dave Lindsay, should that reported be repeated this evening and you have drawn a complete blank as far as trying to find the cause of the problem, I would be inclined to give a company AT800 a quick phone call to find out if any 4G transmitters are being tested in your area, as your findings (re: Humax signal check) are in line with what would be expected if located in "close proximity" to a 4G transmitter, as these transmitters are capable of seriously affecting Freeview reception by swamping (desensitising) the input stage on Freeview receivers. Its not by any means a commonly experienced problem, but it can and does happen in certain situations.
The only reason I mention this aspect over that of possible interference from some domestic equipment operated via a timer, is that initial testing of a new 4G transmitter is not necessarily carried out during daytime hours.
That said, AT800 have up to date information on new 4G installations, and if you haven't received a "free" 4G filter though the post then the aforementioned is not likely to apply.
Just out of curiosity, are you using a roof mounted aerial?, also is the junction box referred to purely a passive (unpowered) device?
AT800 contact details can be seen on the link, should they be required!
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