Fix for missing channels

There are 11 replies in this Thread which was already clicked 4,123 times. The last Post () by bigalan.

    Hi Guys theres been lots on missing channels on this box and I am sure there are several reasons for some of them. The two boxes I have set up both experienced missing HD channels particularly on the Vertical frequency. I measured my output voltage whilst on Sly sports 3 HD ( a missing one) and it was 14.75 volts There are other channels as well like Sly movies 1 Premiere HD etc.
    I ordered a voltage reduction kit off fleabay for £8.55 which fixed the problem. So I decided to make my own and share it with you guys for a fraction of the cost so here goes.


    Kit needed...


    1. some coax cable about 2 ft.
    2. F plugs and a cable joiner (F type)
    3. NP diode or signal diode from maplins QL71N really small little sucker
    4. some connector block. (not needed if u want to solder


    OK just put an F connector on each end of the coax and screw the cable joiner to one end (to Dish end). Now cut the cable in the middle and strip back cable to expose core and screen. Connect as per diagram making sure the positive end of the diode is connected to the reciever end. No big deal if you get it wrong as the output vols will be zilch. Just turn the assembled cable around and put the Cable joiner on the other end. remeasure volts. This should give you around 13.5 to 13.7 volts and all the channels should now pop up. Hope this helps guys. Just made one and tested successfully.


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    PS forgot to add lads. diode is about 59p

    Might have to make one of these as am having the same issues as you , good tutorial m8 ;)


    Mutz

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    Well if it works it works cant argue with that but i would be really surprised if at some point you dont start losing other transponders after doing this because as soon as you start hacking into any cable like that you will lose signal,the dielectric is the part that actually carrys the signal from the lnb to your receiver and in this case its the foam insulation that carrys your signal and as you can see its been disconnected! Mate have a look at your BER (bit error rate) and see if its showing anything as it should be at 0.


    Not slagging anything here its just an obsrvation steve thats all and i,m glad its working.


    Also has anyone tried an inline amp with these boxes as i know that was a specific inline amp that cost about a fiver that sorted all the dm800,s out with the dodgy tuners.


    romman

    Hi Rommam, this has nothing to do with signal level the switching voltage for the LNB between Horizontal and vertical frequencies is as follows...Polarisation switching is controlled by DC voltage supplied by the receiver. 12.5v to 14.5v gives vertical and 15.5 to 18v gives horizontal polarisation. The openbox supplies 14.7 so it never switches from H to V on some channels well at least both mine did. An inline amp wont fix this.


    Dont understand how you think foam insulation carries the signal as this is not the case you need a good quality cable with screen and and shield for instance WF100 the foanm dialectric is an insulator. Take the fact that you use cable joiners the foam dialectric is cut on those. Sorry mate appreciate your input but question your facts anyway BER is 0 and working fine:caz:

    Quote from steve67474

    Hi Rommam, this has nothing to do with signal level the switching voltage for the LNB between Horizontal and vertical frequencies is as follows...Polarisation switching is controlled by DC voltage supplied by the receiver. 12.5v to 14.5v gives vertical and 15.5 to 18v gives horizontal polarisation. The openbox supplies 14.7 so it never switches from H to V on some channels well at least both mine did. An inline amp wont fix this.


    Dont understand how you think foam insulation carries the signal as this is not the case you need a good quality cable with screen and and shield for instance WF100 the foanm dialectric is an insulator. Take the fact that you use cable joiners the foam dialectric is cut on those. Sorry mate appreciate your input but question your facts anyway BER is 0 and working fine:caz:


    Steve i have been on more training courses than i care to remember over a very long period of 18 years and i can assure you the dielectric insulator carrys the db signal from lnb to receiver and any disruption in this causes signal loss! Even an f type barrell is not recommended as it will still introduce some signal loss although i have used them in the past myself but if you look at these barrells they are specifically designed for the job of joining cables to allow a continual flow for the dielectric,albeit your fplugs have to be fitted correctly for the barrell to work correctly, by allowing the foam or plastic insulator to rise out of the tip of the f plug by a couple of mm so it touches the the solid plastic dielectric on the barrel when both fplugges are fully tightened.


    Electrical connector blocks are most definately not designed for this!!


    Outer sheath = obviously to stop water/moisture ingress


    Sheild = an interference barrier to prevent unwanted noise distorting the data!


    Braiding = Acts as a ground and helps the inner core do its job correctly


    Inner core = Voltage!


    I have explained what the dielectrics job is on co-axial cable already!!


    This is why its not a good idea to crush cables or introduce sharp bends on the cable while installing as it crushes the dialectric causing signal problems although foam is the best cable to use as the plastic dielectric crushes easily...


    I,m sorry but i would not recommend anyone does this modification and look for another solution to remedy your openbox problems.


    romman

    Hi Romman,
    I will have to agree to disagree with you on this point as the inner core carries voltage and signal it may propogate into the dialectric and I know that the more joints you have decreases the signal level etc plus avoid 90 degree bends etc etc. we could go on ad infinitum. a quote from many online papers....


    The RG6 is thicker than the RG59, possessing a larger center conductor (which transmits satellite/cable signals and voltage) and a dual or quad shield to reject radio frequency interference that adversely effect satellite and cable installations. The RG6 also has a larger dielectric insulator, which greatly reduces the cable's ability to conduct electricity. Indeed, it can operate to as high a frequency as 1.5 Gigahertz (GHz). Thus, as a thicker cable, the RG6 has better signal quality than the RG59; and is perfect for CATV, satellite and cable applications.


    I appreciate your input and am sure members may find our chat interesting but at the end of the day guys just want to watch their tv. This issue on the openbox affects a lot of hd channels including the new FI and as I said sly movies premiere and ss3hd. This 59p fix sorts it and at the end of the day all I am trying to do is save people some money. This fix has been used on several forums and has been successful and there is a guy selling lots of em on fleabay with 100% feedback on them for this issue and no one has come back saying they have had other problems. Other people have replaced their LNB and Dish and cabling to find that they still have the problem


    If there are the issues that you describe then people can remove it. At the end of the day its a 59p diode and it isn't going to bring your dish system crashing down. I put it up for info for the community, if they use it or not is up to them. The PN diode or signal diode has a characteristic of reducing voltage by about 0.7v this is enough to sot the problem.


    By the way good result for Chelsea last night although a bit lucky Barsa didn't put a few away LOL


    PS. To support your point I did find this...
    Electrical or Radio?
    Cable TV signals are a rather unique phenomenon. They are at the same time an electrical signal and a AM RF signal. When looking at a piece of coaxial cable, the electrical part of the signal is travelling down the center conductor(or more precisely on the outer surface of the center conductor). This electrical signal is very weak comparitively speaking... Where your automobile runs at 12 volts dc and your household electrical at 110 volts ac, we are dealing with 1 mV (milli-volt), that's 1/1000 of a volt across a 75 ohm load with a power of 13 nW(nano-watt = 1 billionth of a watt). So what good is an electrical signal that weak? Answer: it induces, or drives, the RF signal along the dielectric(insulator) core that separates the center conductor from the outer conductor(shielding) of the coax cable.


    I still have to say that if the dielectric was the sole carrier then how do we explain the fix as it works!!

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