Problem with masthead power supply

realdanbreen

I have a 12v masthead power supply in the attic which takes in a cable from the rte aerial outside and has a cable going out to a splitter to several rooms. Every so often(and lately more frequently) the power light goes out. If i leave it unplugged for a good few hours it comes on again. Someone said it appears to be shorting out but how do i correct this?

byte

You'll need to find where the potential short is.

That could be a joint or break in the cable allowing water ingress. Or the masthead amp itself could be faulty (the power supply can't be ruled out as being faulty either).

Do you find the issue more likely in rainy weather?

realdanbreen

byte wrote: »

You'll need to find where the potential short is.

That could be a joint or break in the cable allowing water ingress. Or the masthead amp itself could be faulty (the power supply can't be ruled out as being faulty either).

Do you find the issue more likely in rainy weather?

TBH I thought it occurred more often in hot weather. I have changed the PSU but have the same problem.

Cerco

Is the power supply connected to a resistive splitter?
If so then you need to isolate it using a diplexer.

Feed the mast head amp directly and split the signal using a diplexer. After the diplexer you can use resistive splitters if you wish.

Mooshroom

Cerco wrote: »

Is the power supply connected to a resistive splitter?
If so then you need to isolate it using a diplexer.

Feed the mast head amp directly and split the signal using a diplexer. After the diplexer you can use resistive splitters if you wish.

Not sure what your point is here.

If the PSU is in the attic, it's most likely directly connected to the amplifier, with the splitter 'downstream'. Actually, this is how it's described in the OP.

Does the resistive element in RF signal splitters affect DC power passing anyway?

realdanbreen

Cerco wrote: »

Is the power supply connected to a resistive splitter?
If so then you need to isolate it using a diplexer.

Feed the mast head amp directly and split the signal using a diplexer. After the diplexer you can use resistive splitters if you wish.

It's like this. I have a satellite dish from which I get all the bbc's, ITV'S, young wans half stripping off ete etc, no problem,no bills.
I also have an aerial to receive the RTE,s TV3'S etc and that is where my problem is arising with the psu. I would have thought it should be pretty much a plug & play situation in this day and age, in other words I just want to receive RTE etc. How do I do this without having to go through a big rigmarole with a TV installer?

The Cush

realdanbreen wrote: »

I also have an aerial to receive the RTE,s TV3'S etc and that is where my problem is arising with the psu. I would have thought it should be pretty much a plug & play situation in this day and age, in other words I just want to receive RTE etc. How do I do this without having to go through a big rigmarole with a TV installer?

The PSU is in the attic, is the masthead amp located on the aerial mast?
How long has the masthead amp been in use, pre-Saorview days?
Do you still require the masthead amp, I removed my one last year and just use a distribution amp in the attic fed direct from the aerial.

Mooshroom

realdanbreen wrote: »

I also have an aerial to receive the RTE,s TV3'S etc and that is where my problem is arising with the psu.

Is there an amplifier on the aerial at all, or did you just plug the cable from the aerial into the PSU for an amplifier?

Maybe you're just getting a partial failure of reception, you check & see the PSU is off & assume that's the problem, even though it might have been off for days & the reception problem is completely unrelated?

Cerco

Mooshroom wrote: »

Not sure what your point is here.

If the PSU is in the attic, it's most likely directly connected to the amplifier, with the splitter 'downstream'. Actually, this is how it's described in the OP.

Does the resistive element in RF signal splitters affect DC power passing anyway?

The splitter must be isolated from the dc voltage provided by the psu. This may be done by the positioning of the psu or by using a diplexer. If the splitter is not isolated then current will flow through the resistive elements, loading the psu.

Mooshroom

Ah right, feed power to the amplifier through 1 leg of a diplexer, with the 2nd going to the splitter?

I'd just swap the splitter for the type intended for line-powering use.

Cerco

First thing to do is determine if the psu is feeding into the splitter. If so then determine , as suggested above, if the amp is still required. After that op can look at the diplexer option if required.

Mooshroom

As I mentioned already, I wouldn't be surprised if there's no amplifier at all.

With no way of assessing the OP's competence in this area, I don't think it does any harm to ask questions that might even seem a bit insulting.

realdanbreen

Mooshroom wrote: »

As I mentioned already, I wouldn't be surprised if there's no amplifier at all.

With no way of assessing the OP's competence in this area, I don't think it does any harm to ask questions that might even seem a bit insulting.

You needn't worry about insulting me as I haven't a clue about this kind of thing,nor do I have any interest in it. If I were to start from scratch-how do I receive RTE,TV3 etc? I live out from the city,no cable TV, and have the saorview box etc. I also have the proper aeriel on the chimney.

The Cush

realdanbreen wrote: »

I also have the proper aeriel on the chimney.

Regarding my questions above where is the masthead amplifier located, is it on the aerial mast?

realdanbreen wrote: »

If I were to start from scratch-how do I receive RTE,TV3 etc? I live out from the city,no cable TV, and have the saorview box etc. I also have the proper aeriel on the chimney.

If the signal strength/quality is good enough at the aerial run a cable directly from the aerial to a distribution amplifier in the attic and from there to the various TV points.

Using the Saorview coverage checker what is the nearest Saorview transmitter and how far away is it?

Mooshroom

realdanbreen wrote: »

If I were to start from scratch-how do I receive RTE,TV3 etc? I live out from the city,no cable TV, and have the saorview box etc. I also have the proper aeriel on the chimney.

Who installed your current TV reception setup? Do you know is the terrestrial side completely separate from the satellite side, no shared cables? You know that the thing you refer to as a "masthead power supply", is just that: a device for injecting power (usually 12 volts, maybe 100 milliamps max. current) into the coaxial cable?

The power supply doesn't provide any amplification, the amplifier is a separate device that is typically mounted as close to the aerial as possible (hence the "masthead" name), so you need the remote power supply if you want to put the amplifier outside.

If there is indeed no actual amplifier in your system, you could just replace the PSU (& splitter) with a distribution amplifier, as mentioned in the previous post, & see how it goes.

realdanbreen

Mooshroom wrote: »

Who installed your current TV reception setup? Do you know is the terrestrial side completely separate from the satellite side, no shared cables? You know that the thing you refer to as a "masthead power supply", is just that: a device for injecting power (usually 12 volts, maybe 100 milliamps max. current) into the coaxial cable?

The power supply doesn't provide any amplification, the amplifier is a separate device that is typically mounted as close to the aerial as possible (hence the "masthead" name), so you need the remote power supply if you want to put the amplifier outside.

If there is indeed no actual amplifier in your system, you could just replace the PSU (& splitter) with a distribution amplifier, as mentioned in the previous post, & see how it goes.

OK, a recognised installer set it up
The terrestrial is seperate from the satellite-which is working fine
The device which is causing me problems is a ' 12v DC Mashead power supply' thats what is written on it. it works sometimes and other times doesn't-the power on indicator goes off.

Mooshroom

realdanbreen wrote: »

OK, a recognised installer set it up

... The device which is causing me problems is a ' 12v DC Mashead power supply' thats what is written on it. it works sometimes and other times doesn't-the power on indicator goes off.

Well, if the original power supply was installed by a "professional", I think it's safe to assume that there is an amplifier on the other end of the cable. How long ago was it installed?

If you don't want to get the installer back, the next step would be to examine the cable between power supply & amplifier, & the amplifier itself. You'll probably just end up swapping those out too, trial & error, as a fault might not be obvious.

Mooshroom

The Cush wrote: »

... Do you still require the masthead amp, I removed my one last year and just use a distribution amp in the attic fed direct from the aerial.

That's just replacing one kind of amplifier with another, & a distribution amp. will usually have a worse noise figure than a masthead type, not to mention that the masthead gets the amplification in as soon as possible, before any cable losses between aerial & distribution point, though the latter wouldn't be a big problem in most domestic installations.

Some people seem to regard mastheads as a separate species to other amplifiers, that the problems they can cause are somehow different to those that can be caused by any amplifier. The old problem was interference picked up (& radiated) by the amplifier itself, made worse by being outside & high up, but modern mastheads should be well screened against this.

Cerco

Mooshroom wrote: »

That's just replacing one kind of amplifier with another, & a distribution amp. will usually have a worse noise figure than a masthead type, not to mention that the masthead gets the amplification in as soon as possible, before any cable losses between aerial & distribution point, though the latter wouldn't be a big problem in most domestic installations.

Some people seem to regard mastheads as a separate species to other amplifiers, that the problems they can cause are somehow different to those that can be caused by any amplifier. The old problem was interference picked up (& radiated) by the amplifier itself, made worse by being outside & high up, but modern mastheads should be well screened against this.

I think you are confusing the remedy suggested. Cush was asking if the masthead amp was required now presumably because of the increased power of the transmitters on Saorview.
The distribution amp would not replace the mast head amp, it would just amplify the split signal.

If the system was professionally installed then I would look for damage to the feeder cables and check for moisture in the masthead amp. Would not suggest you climb poles or go up ladders unless you are experienced at that.

The Cush

Mooshroom wrote: »

That's just replacing one kind of amplifier with another, & a distribution amp. will usually have a worse noise figure than a masthead type, not to mention that the masthead gets the amplification in as soon as possible, before any cable losses between aerial & distribution point, though the latter wouldn't be a big problem in most domestic installations.

He appears to have a problem somewhere between the power supply and aerial. He said earlier he replaced the power supply but the fault remains so the problem may be closer to the aerial, masthead amp maybe or cabling or connection somewhere.

It would simplify the setup if he were to remove the masthead amp from the aerial feed if the signal is good enough and simply install a clean cable direct from the aerial and distribution amp to feed the various TV points.

realdanbreen

I probably should also mention that sometimes everything works fine! I could go home this evening, plug in the power supply and bobs your uncle.
Alternatively I could plug it in and zilch! nothing happening. What I am trying to achieve is just a constant reception of RTE etc.

Mooshroom

Cerco wrote: »

I think you are confusing the remedy suggested. Cush was asking if the masthead amp was required now presumably because of the increased power of the transmitters on Saorview.
The distribution amp would not replace the mast head amp, it would just amplify the split signal.

The OP's masthead amp is feeding a passive splitter. It's performing the same function as a distribution amp.

As I said, mastheads are not some special device, apart from all other amplifiers. Getting the amplification in as soon as possible is to improve the signal to noise further downstream. Mightn't be necessary for satisfactory viewing: might just be a choice of configuration. Indeed, if all cables have to be run externally & amplification is needed, you wouldn't have much choice but to use an external amp, with the PSU at 1 of the TV points.

The Cush

realdanbreen wrote: »

I probably should also mention that sometimes everything works fine! I could go home this evening, plug in the power supply and bobs your uncle.
Alternatively I could plug it in and zilch! nothing happening. What I am trying to achieve is just a constant reception of RTE etc.

Intermittent fault that's difficult to diagnose and even more difficult over an internet forum.

If you don't feel competent getting up on a ladder to the aerial to check/repair/replace the cable/masthead amp it might be better to get the professional installer back.

The Cush

Mooshroom wrote: »

The OP's masthead amp is feeding a passive splitter. It's performing the same function as a distribution amp.

As I said, mastheads are not some special device, apart from all other amplifiers.

Yes I'm aware of all that but now someone has to get up on the roof the to sort it out the current setup. If the Saorview signal is good enough from aerial to attic why not replace the existing setup with a distribution amp in the attic so he won't have to go thru all this at some point in the future. If the distribution amp was to fail in future it would be a simple DIY job without having to call in an installer again.

Mooshroom

realdanbreen wrote: »

The device which is causing me problems is a ' 12v DC Mashead power supply' thats what is written on it. it works sometimes and other times doesn't-the power on indicator goes off.

What's the make of the PSU? Ones I can think of, the power light will change from green to red if there's a short, like could be caused intermittenly by moisture, it doesn't just go out.

I don't know if this PTC fuse can trip with excessive ambient temperature but 0 - 40C is typically given as the operating temparature range for these PSUs.

The masthead amplifiers typically work away just fine. Most modern ones are in a sealed metal box inside a weatherproof cover that should protect the cable connections too.

realdanbreen

Mooshroom wrote: »

What's the make of the PSU? Ones I can think of, the power light will change from green to red if there's a short, like could be caused intermittenly by moisture, it doesn't just go out.

I don't know if this PTC fuse can trip with excessive ambient temperature but 0 - 40C is typically given as the operating temparature range for these PSUs.

The masthead amplifiers typically work away just fine. Most modern ones are in a sealed metal box inside a weatherproof cover that should protect the cable connections too.

I dont know the make offhand.When its working a red indicator light is on.
When the light goes off, no RTE etc.If I leave it for 24 hours or so and plug it back in it works again until the next time the light goes out.

Mooshroom

The Cush wrote: »

If the Saorview signal is good enough from aerial to attic why not replace the existing setup with a distribution amp in the attic so he won't have to go thru all this at some point in the future. If the distribution amp was to fail in future it would be a simple DIY job without having to call in an installer again.

Of course that's worth considering, given there is already a power outlet in the attic & all. (Even if there wasn't, you could still move the masthead amp., or install any type that can be line-powered, in the attic, & continue using the prior powering arrangement, i.e. the PSU plugged in at a TV point, feeding power to the amp. through a suitable splitter.)

I think it was the fuss about TETRA interference a while back that gave some the idea that all masthead amplifiers are "trouble", rather than just the unscreened, unfiltered types.

realdanbreen

Sorted at long las folks. I opened the psu,even though its a sealed unit. The brown live wire was badly pinched (it could have happened when the back was being screwed down in the factory)I feel like a kid in a sweet shop now,watching ads and everything! Thanks for all the help folks.

Bayonne

realdanbreen wrote: »

Sorted at long las folks. I opened the psu,even though its a sealed unit. The brown live wire was badly pinched (it could have happened when the back was being screwed down in the factory)

Same problem with both dodgy PSUs? Is a pinched wire even a problem, as long as it hasn't been partially cut?