Dodgy/underpowered amplifier?

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E3xtc

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#191242 29-Jan-2016 07:36

Is the following scenario indicative of a broken amplifier, or an amplifier that just doesn't have enough <something> or something else:

I started to write this out but it got too confusing with different TV's - we have 3 in total. So lets reference TV-A and TV-B in the story :)

I noticed that the reception on TV-A was horrible on most of the channels (some channels are fine) - running with DVB-T. When watching on another TV (TV-B), the reception is fine.

The cable on TV-B has the power source for the masthead amp running through it. So I unplugged the amplifiers power source and moved it to TV-A's socket (I know I was able to do this as the person installed one that didn't need the amp to be located on a specific outlet). Plugged it all in, and TV-A is now working fine.

I go back to the TV-B and plug in the aerial (which now has no amplifier power attached), and it works fine. Returning to TV-A I find this is now no longer working :\

So I think this is a bit weird. So I power off the amplifier power supply, remove the other TV-B's aerial cable from the wall plate and sit down to have something to eat and think about it a bit. Then after about 30 min I turned the power back on to the amplifier power supply (still in TV-A's wall plate), and TV-A is back to working fine.

So does this indicate that the amplifiers power supply can't supply enough signal strength to be split over 3 (ie the total number of plugged in TV's in the house) wall plates? Any thoughts on how I could resolve this? Its not that much of a big deal tbh because with TV-B it's used primarily for movies, gaming, and we can stream from our main DVB-T receiver to it anyhow, but it just makes me wonder

Thanks

RunningMan

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#1481029 29-Jan-2016 08:15

The weak link is plugging in TV-B.

When this is connected, TV-A stops working, regardless of where you have the power injector plugged in. When you disconnect TV-B, then TV-A starts again.

You said 3 TVs - what happens with the third as you connect and disconnect TV-B?

With DVB broadcasts, you hit a wall where the signal is too weak and you lose picture. It is likely that your signal is very weak, and connecting more than 1 TV at a time is enough to drop the signal below a usable level for TV-A.

If this is a recent development, go back to basics - has the antenna moved in the wind, cable got water in it recently - that sort of thing.

EDIT: Spelling

E3xtc

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#1481036 29-Jan-2016 08:32

I knew you were going to ask about that third TV - and tbh in my shagging around last night I ignored it as it was close to where a baby was sleeping. But will have another play and find out.

One thing I didn't mention earlier is that, even after unplugging TV-A (after realising re-plugging it back in degraded TV-B again), TV-B still didn't work. Only did it start working again after the amplifier power supply was turned off for a while. I tried turning it off and on immediately, but this made no difference - ie TV-B was still not working.

Your assumption with our signal being weak is probably pretty accurate. Am wondering if it is worthwhile to change from the type of aerial that looks like an arrow (X Type??) to a phased array one...

The situation has been progressively getting worse this year to the point where most channels were knocked out, and is consistent with last year in that it gets worse when the weather gets hot and fine.

bales

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#1481064 29-Jan-2016 09:38

sounds like you need a signal test done to check strength and quality what area are you in.

keithbayly

E3xtc

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#1481067 29-Jan-2016 09:44

I know signal is marginal - no argument there - am in Titirangi, Auckland - so in a valley with no direct line of sight.

But yeah, just trying to understand the behaviour of the components in place, as it sort of seemed to me as though the amp was unable to feed to all 3 outlets.

Another question - why would physically unplugging the TV-B aerial (ie reducing connected TV's to 2 from 3) make a difference (even TV-B wasn't actually turned on)?

B1GGLZ

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#1481189 29-Jan-2016 12:53

E3xtc:

I know signal is marginal - no argument there - am in Titirangi, Auckland - so in a valley with no direct line of sight.

But yeah, just trying to understand the behaviour of the components in place, as it sort of seemed to me as though the amp was unable to feed to all 3 outlets.

Another question - why would physically unplugging the TV-B aerial (ie reducing connected TV's to 2 from 3) make a difference (even TV-B wasn't actually turned on)?

Sounds like there could be a problem with the splitter or even the cables you are using to connect TV to wallplate may be inferior quality.

Have you thought about installing more than one antenna? i.e. one antenna and amp for each TV. More complicated but does away with the need for a splitter.

Another option would be a decent distribution amp. Something like this

http://matchmaster.co.nz/domestic/amplifiers/10mm-dda24

E3xtc

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#1481194 29-Jan-2016 13:05

I did have a dude come around and check cables/wallplates/splitter about a year ago - not to say that he didn't miss something, but I would hope he would have found something amiss at that time :\

The idea of multiple antenna isn't going to roll sorry - but thanks for the idea.

So how is that distribution amp different from a masthead amp. If I got the distribution amp, would I still need to retain the masthead one?

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B1GGLZ

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#1481254 29-Jan-2016 14:50

E3xtc:

So how is that distribution amp different from a masthead amp. If I got the distribution amp, would I still need to retain the masthead one?

Your masthead amp boosts the signal then your splitter undoes all the good work depending on how many TVs you plug in and how lossy it is. The distribution amp takes the antenna input (from masthead amp in your case) then outputs at constant level on all outputs. Probably fairly pricy though. The brochures here under the downloads tab give lots of info. No guarantee it will work if the antenna input is dubious to start with but worth a try. Shouldn't make it any worse.

http://matchmaster.co.nz/domestic/amplifiers/10mm-dda24

richms

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#1481266 29-Jan-2016 15:13

If you have an all ports power pass splitter so you can move the power adapter to wherever, then you in theory should have power blockers on any TV's that are not using the power adapter. They may be shorting out the power adapter making the amp not get the amount of power it should be.

That is why generally you have a splitter that has a specific power pass port, and the rest all have the capacitors in them to allow the signal thru but no the AC/DC for the amplifier.

If the splitter isnt made for power pass at all and is just relying on the wire in the transformers in the splitter, then the DC current thru it can cause them to not work properly. A proper power pass splitter blocks the DC from the transformers with capacitors, and then puts inductors in to allow the DC a direct path from input to output.

Richard rich.ms

E3xtc

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#1481311 29-Jan-2016 15:52

richms:

If you have an all ports power pass splitter so you can move the power adapter to wherever, then you in theory should have power blockers on any TV's that are not using the power adapter.

Hmm okay - a power blocker...never heard or seen one of those....where would I get one?

richms

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#1481316 29-Jan-2016 15:58

I used to get all my antenna stuff from clayworth but they seem to have gone now. Anywhere that sells masthead amps should have them available. Also used when you have an IR over coax system to block it from going into the TV's

Richard rich.ms

E3xtc

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#1481323 29-Jan-2016 16:03

B1GGLZ:

E3xtc:

So how is that distribution amp different from a masthead amp. If I got the distribution amp, would I still need to retain the masthead one?

Your masthead amp boosts the signal then your splitter undoes all the good work depending on how many TVs you plug in and how lossy it is. The distribution amp takes the antenna input (from masthead amp in your case) then outputs at constant level on all outputs. Probably fairly pricy though. The brochures here under the downloads tab give lots of info. No guarantee it will work if the antenna input is dubious to start with but worth a try. Shouldn't make it any worse.

http://matchmaster.co.nz/domestic/amplifiers/10mm-dda24

So its possible to use one of these with a masthead amp, and the distribution amp, just passes the power through (to the masthead amp)? They both need power by the looks of things, so not quite understanding how that might work....hmmm...sorry you can tell I have no idea really :)

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RunningMan

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#1481431 29-Jan-2016 19:07

richms:[snip]

I used to get all my antenna stuff from clayworth but they seem to have gone now.

They're still selling on TradeMe http://www.trademe.co.nz/Members/Profile.aspx?member=192159

richms

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#1481439 29-Jan-2016 19:23

RunningMan:

richms:[snip]

I used to get all my antenna stuff from clayworth but they seem to have gone now.

They're still selling on TradeMe http://www.trademe.co.nz/Members/Profile.aspx?member=192159

Ah sweet. Sign was gone on hillside rd and the websites dead so I assumed the store was too.

These are what you want on any unused output if you are keeping on using the same splitter http://www.trademe.co.nz/electronics-photography/tvs/terrestrial-receivers/auction-1024959364.htm just to be sure that the other devices are not loading down the DC at all. Really you want to swap the splitter out for a single port power pass and ensure that the amps power adapter is connected to that port.

Also terminate the other outputs that you are not using on the splitter. I have had that help at a relatives place with grotty multipathed signal. Not an issue at home with multiple 8 way splitters with unused runs.

Richard rich.ms

B1GGLZ

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#1481440 29-Jan-2016 19:24

E3xtc:

So its possible to use one of these with a masthead amp, and the distribution amp, just passes the power through (to the masthead amp)? They both need power by the looks of things, so not quite understanding how that might work....hmmm...sorry you can tell I have no idea really :)

As far as I can tell from the documentation the distribution supplies power for the masthead amp if fitted as well as for a dish's LNB on the other input port. The picture of the unit indicates switches to select power off or power on to antenna, dish or both. No need for separate power supply for the masthead amp. And no splitter in-line to attenuate the signals.

bales

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#1481809 30-Jan-2016 14:58

yes the dist. amps from matchmaster have a switched feed for m/h amps

keithbayly