Advice needed

[nivenj]

Hey all,

Not an electrician so be gentle.

Strange problem and need some advice. My local pub has asked me to fit a multi TV setup so the can show media from a single source to multiple TV's round the pub. Current setup has the media player out put going into an amplifier/splitter which then goes to 3 TV's around the pub. 1 TV image was perfect, 1 was so-so and the other unwatchable with wavy lines all over the place however this is only when watching the single media source, all TV's are perfect image when tuned to their own individual TV station.

After much investigation and a few extension cables I deduced that depending what power socket the TV is plugged into determines what the picture was like. If I run everything from the same power point the media player is on, all screens are perfect.

I know that TV's get their sync from the frequency of the mains power, so it would seem to me that the frequency of mains supply to the media player is different to the mains power feeding his TV's, and to some extent these are different to each other as well.

Any ideas how we can solve this? He's talking about getting a "clean" circuit put in to feed only these devices. Would this help? Is there a simpler solution?

thanks guys

 

[Sintra]

Hey all,

Not an electrician so be gentle.

Strange problem and need some advice. My local pub has asked me to fit a multi TV setup so the can show media from a single source to multiple TV's round the pub. Current setup has the media player out put going into an amplifier/splitter which then goes to 3 TV's around the pub. 1 TV image was perfect, 1 was so-so and the other unwatchable with wavy lines all over the place however this is only when watching the single media source, all TV's are perfect image when tuned to their own individual TV station.

After much investigation and a few extension cables I deduced that depending what power socket the TV is plugged into determines what the picture was like. If I run everything from the same power point the media player is on, all screens are perfect.

I know that TV's get their sync from the frequency of the mains power, so it would seem to me that the frequency of mains supply to the media player is different to the mains power feeding his TV's, and to some extent these are different to each other as well.

Any ideas how we can solve this? He's talking about getting a "clean" circuit put in to feed only these devices. Would this help? Is there a simpler solution?

thanks guys

Yes a clean circuit for the TV's could help.

Do you know if all the TV's and media player are plugged into sockets on the same phase?

 

[sparks1234]

I would agree there could be a phasing issue here

 

[nivenj]

I not sure i'm afraid. When you say phase, do I understand that to be fed from the same elctrical circuit. ie, fed from the same breaker on the fuse panel? If so, then no, they are on different breakers. One of the TV's, the worst one, is actually fed from a spur coming down from the upstairs circuit, another is fed from a circuit that was put in for a building extension and the third from the origonal downstairs circuit.

As an aside, there does seem to be a history with his electrics. He has one freeview box that sometimes looses power. If he unplugs it and plugs it back into the same socket the power still wont come on. He has to unplug take it to a different socket, plug it in, power comes on, unplug then take it back to the origonal socket and the power then comes on. That just baffles me that one

 

[Sintra]

I not sure i'm afraid. When you say phase, do I understand that to be fed from the same elctrical circuit. ie, fed from the same breaker on the fuse panel? If so, then no, they are on different breakers. One of the TV's, the worst one, is actually fed from a spur coming down from the upstairs circuit, another is fed from a circuit that was put in for a building extension and the third from the origonal downstairs circuit.

As an aside, there does seem to be a history with his electrics. He has one freeview box that sometimes looses power. If he unplugs it and plugs it back into the same socket the power still wont come on. He has to unplug take it to a different socket, plug it in, power comes on, unplug then take it back to the origonal socket and the power then comes on. That just baffles me that one

No phase is nothing to do with the breakers. If the pub has a 3 phase supply ie 400v then each phase gives 230V phase to neutral and 400V phase to phase. If this is the case and the sockets are on different phases the freqeuncy cycles would be 180 degrees apart and could cause interference.

Normally on a 3 phase installation every 3rd circuit breaker would be on the same phase.

Hope this helps a bit.

 

[nivenj]

No phase is nothing to do with the breakers. If the pub has a 3 phase supply ie 400v then each phase gives 230V phase to neutral and 400V phase to phase. If this is the case and the sockets are on different phases the freqeuncy cycles would be 180 degrees apart and could cause interference.

Normally on a 3 phase installation every 3rd circuit breaker would be on the same phase.

Hope this helps a bit.

Ah yes, I understand what you mean now. I'm not sure if he has 3 Phase I'll ask and get back to you. If it is phasing issue, am I correct in thinking the only solution is to get them all on the same phase? If so, probably just as easy getting a new clean circuit installed as the positions of the TV's are fairly fixed?

 

[Sintra]

Ah yes, I understand what you mean now. I'm not sure if he has 3 Phase I'll ask and get back to you. If it is phasing issue, am I correct in thinking the only solution is to get them all on the same phase? If so, probably just as easy getting a new clean circuit installed as the positions of the TV's are fairly fixed?

Yes you could change all relevant circuits to the same phase in the distribution board if this can be achieved without disrupting the balance of the phases.

 

[Davey101]

People in the AV world recommend not putting AV stuff on a 'Ring main', as you can get ground loop 'hum'. The best advice seems to be to run a radial circuit to the relevant bits of kit. I'd doubt that this is your problem though, just something to bear in mind.