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Masthead amp failed (mother-in-law driving me nuts!)

Discussion in 'Audio Visual' started by Newboy, 26 May 2017.

  1. As the title says, masthead amp has failed (4 feeds into 4 rooms). The mast location is v. difficult to get to.

    It is possible to add a local signal amp in one of the rooms as a solution to no TV signal?
     
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  3. oldbutnotdead

    oldbutnotdead

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    If it is that hard to get to, how do you know it has failed?

    Are you getting any channels at all (even radio) in any of the rooms? If not then no a local booster probably won't help, you'll be amplifying no signal so you'll just get a load of noise
     
  4. Lucid

    Lucid

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    More likely to be a failed (or disconnected) power supply. That's better news as it is easier to deal with.

    You've either got something like this masthead amp power supply, or one of the TVs or a set top box / PVR has an option to power an amp via coax. If you have the little plug in box (that most people mistakenly think of as a booster ) then check it is still plugged in and switched on. It's worth also checking the fitment of the plugs on the coax cables. If they're the screw-on type then something as simple as vacuuming "behind the telly" might have knocked something loose.

    If you know that your MILs install uses a TV or STB to power the amp then double check the menu settings and of course that the TV is still powered on at the wall socket. It's not out of the ordinary to find someone switched off the socket for the TV in the spare bedroom, or changed the main TV or replaced a STB and now the system doesn't work.


    As for adding a booster somewhere else, no, that won't work. Without power the masthead amp is dead, and dead it doesn't pass any signals at all. If there's no signal then it doesn't matter how powerful an amp you fit somewhere else, it has nothing to amplify. Game over.


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  5. No signal in any room, power supply to amp seems to be working (power light/indicator lit).

    Worth swapping over to a new power supply?
     
  6. Lucid

    Lucid

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    Check your cables and connections first. You particularly want to look at the cable going to the "AERIAL" or "RF IN" side of the power supply. This is where the power is coming from. If the plug end has been poorly fitted and there's even a single strand of the shield braid touching the centre core then that's enough to stop any power getting to the masthead amp.

    If you have a multimeter and know how to set it to DC range measuring up to 20V then you can check there's a voltage coming from that socket. Unplug the aerial cable connection, use a clothes/sewing pin to make a contact in the centre connection, red (+ve) probe to that, black probe (-ve) to the threaded outer part. Read the measurement from the PSU. You should get a reading of around 12V. If you do then the power supply is probably fine. The issue could be the masthead amp or it could be a short in the cable running up to it.
     
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  7. Thanks - a couple of things for me to check then.

    Another question - the power supply to the amp - can this be connected to any of the 4 coax feeds?
     
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  9. Lucid

    Lucid

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    I'm tempted to say yes because ProCeption, Wolsey, Labgear, Vision-Optima and Antiference all accept power on any output. However, I'm sure there'll be some make somewhere that bucks the trend. What I'd suggest is try it and see. If it is a cable fault then choosing a different output means you'll be powering by a different cable and that might be enough to get you by.
     
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  10. Many thanks - looks like a fun Saturday at the MIL's!
     
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  11. ericmark

    ericmark

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    I also have a problem with a mast head amp where we can no longer access it, next door built a garage where we would have put ladder, I have had aerial fitter around with his box, which showed great signal, but within a short time of him leaving the TV again failed, I went into TV menu and set TV to output power instead of using the power supply, this seemed to work fine.

    When the TV was replaced found new one did not have output to aerial so bought a new power supply. Started to get problems again, both with old and new power supply, I removed the aerial wall plate and connected direct, same results what ever I do works for so long then fails, I have noted the power supplies are 12 volt, but the TV output was 5 volt, it does seem with the 12 volt something is failing after some time, but with 5 volt it just runs and runs. I will guess there is a fault with the mast head amplifier and something is over heating in it?

    I have given up and had a satellite dish fitted on the wall low enough that I can reach from a set of steps, I have given up with freeview as also other issues with the TV asking to be re-tuned every couple of days. However since my mast head amplifier seems to work better from the 5 volt output of TV than the 12 volt power supply, maybe yours will be the same?

    Before living with my mother it was really a pain, as soon as power removed and re-instated the mast head amp would work, so seemed impossible to find the fault. Could even be a little water in the amp and it stays as water with 5 volt but becomes a saturated mist inside the box at 12 volt, but what ever was happening it worked on 5 volt 24/7 but not on 12 volt which was the voltage of the original power supply that was supplied with the mast.
     
  12. bernardgreen

    bernardgreen

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    It might be a themally protected regulator in the mast head that has somehow lost its ability to dissapate the heat produced when regulating down from 12 to the working voltage for the amplifier. Hence it over heats and shuts down. Maybe corrosion has affected the heat sink and teh regulator is detached from it.

    Some mast heads have a small anti condensation heater fitted inside the case and some use waste heat from the regulator for that function.
     
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  13. Sam Gangee

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