Puzzle

[andyb32]

Hi, there seems to be an electrical problem in my house; the cause of which eludes me.

Basically, it is causing my TV screen to appear tinted blue before cutting out, and my hi-fi amplifier cuts out (there is a message "Protect" that appears on the display before it cuts out). This normally happens after the equipment has been operating normally for anything between 30 minutes to several hours (so I wonder if it's heat-related?).

I've even tried using another TV (I did think my TV was faulty, so I sent it to a repairer who told me there was nothing wrong with it) which also cuts off (the "standby" LED pulsates on/off). I've also tried a different amplifier and that cuts out too, so I'm pretty sure it can't be the equipment that is faulty.

Also, my DVD player stopped working (will play CD's but not DVD's), so I wonder if the laser is damaged. All rather strange.

I have had an electrician call round to the house to check the supply in the garage, and all seems normal. He asked me whether the lights go dim at all in the house, which they don't.

Also, he checked the double plug socket in the lounge and concerned that it may be overloaded by high frequency TV/HI-FI gear, he suggested fitting a few (5) double plug sockets.

I followed his advice and told him to go ahead and fit the plug sockets. The problem still persisted (only happens to that equipment in my lounge), so I connected the TV up via an extension cable and plugged it in upstairs. Still the same problem.

I contacted the electrician again and told him the problem was still apparent. He did mention that it might be my dual electricity meter (has an on/off peak time clock), so I've arranged for the electricity board to come out and fit a standard electricity meter. They're going to do this next week.

It seems to be a very strange intermittent problem I've never experienced before. I've been living there for nearly 2 years and it has only recently become a problem.

If fitting the standard electricity meter doesn't do the trick, then perhaps mystic meg will have the answer, who knows.

I wonder if anybody on here has a similar experience and can shed some light on this mystery?


Thanks,

Andy.

 

[Lectrician]

My only thought would be over voltage.

 

[andyb32]

Apparently, the voltage supplied from the grid is 242 volts, but I'm told that the appliances will tolerate between 220 - 250volts.

Andy.

 

[plugwash]

electricians DON'T have the test equipment to troubleshoot theese kinds of problems

all that electricans carry round with them is a few very special perpose testers for doing the tests the wiring regs require and possiblly a multimeter.

you need equipment that can both see the problems and log its results over a period of a week or so this equipment does not come cheap. Sometimes the electrcity board will supply it if you complain enough but its likely to be difficult to persude them to do so.

I STRONGLY suspect that the problem is not in your house.

 

[jtaunton]

Grasping at straws, but you haven't got a neighbour who has a knackered microwave, or is a radio ham or russian spy or something ??

 

[andyb32]

I must admit, I did suspect that the cause of the problem is not specifically in my house, so I spoke to one of my neighbours, but he doesn't have this issue.

It seems strange that after nearly 2 years, it is only an issue now.

Maybe I should nag the electricty board.


Andy.

 

[Big_Spark]

Do you have a microwave oven reasonably near to this equipment? What you are describing sounds unerringly like Electromagnetic interference, and the obvious cause of this is a Microwave. The Magnetrons can develope faults that cause supply issues, and the microwaves will interfere with TV pictures and electronics if the leak from the oven is sufficient...it need not be a big leak either.

One way to check the supply is to plug a surge and transient voltage protective extension into the socket, then plug the equipment into that. If it is transients and surges, this will kill them.

 

[andyb32]

The microwave is in the kitchen -which is not near the TV/Hi-Fi in the lounge.

Interestingly, I did have the TV/Hi-Fi plugged into a 6 gang surge extension, and the problems were apparent then.

My electrician thought that this setup may be exerting a high load, and suggested that I have him install the separate double sockets.


Andy.

 

[supersparks]

try your neibours 2 doors up from yours and 2 doors down.

electricity is distributed in 3 phases

for example a street with 9 houses will run like this

house1 phase 1
house2 phase 2
house3 phase 3

house4 phase 1
house5 phase 2
house6 phase 3

house7 phase 1
house8 phase 2
house9 phase 3

so, find neibours on the same phase and see if they have similar problems.

other thing it could be, at a long shot is a thermal fault
i.e. after a long period a wire someware is "breaking" when it heats and deforms and as it cools down it makes the connection again...

 

[theshogun]

Doe's this occur at specific times of the day or night ?

 

[HDRW]

Andy,

I think you need to find what the cause is and attack that, rather than changing things willy-nilly. I'd bet folding money that changing the meter doesn't help!

It sounds like it could be either EMI, or some sort of glitch on the mains where the voltage is either going high or low suddenly. You can get meters that monitor the mains and report this sort of thing ("Dranetz" is one make) but you wouldn't want to buy - or even hire - one because they are seriously pricey! See if you can get the electricity board to put one in for a while.

As a quick cheap thing you can try, get a plug-in RCD apaptor - the type that drops out if the mains fails - and plug it in next to the TV. Activate it, and see if it stays engaged long-term. If there's a momentary voltage dip, it should disconnect, so you'll at least know that's happened. This is rather crude, but for seven or eight quid (assuming you don't already have one) it's about all you can do!

As for EMI, have a look round and see if any of your neighbours have transmitting equipment (spot-the-antenna). Also see if a mobile phone tower has recently been commissioned (up to a few hundred yards away). Oh, and another thought: TETRA: the new radio system the emergency services are (or are soon) starting to use. See if you can find out if there's a mast for this nearby.

Cheers,

Howard

 

[delmel]

Screen going funny colour def sounds like EMI. How close are your speakers and are they shielded. The screen and turning off problem may not even be connected could be seperate issues.

 

[andyb32]

I'd really like to thank everybody who has replied to this thread so far. You have each raised valid and valuable points that will definitely help my process of elimination in trying to ascertain the cause of this phenomena.

As regards the EMI; I do have some surround sound speakers which are nearby the equipment, but are shielded by design for this reason.

I don't believe that changing the meter will help with this particular problem, but I do believe that it will reduce my electricity bill somewhat, and it's one more possibility to strike off the list.

The RCD adaptor sounds like a good idea. I don't believe I have one of those devices, so I'll browse the web & hopefully buy one.

Ah yes, I forgot, a mobile phone transmitter has recently been installed in a field up the road from my house (a couple of hundred yards or so). Perhaps this is causing it -although I would imagine that there are strict regulations that they must adhere to, and that the engineers would have tested that the emissions, etc. comply with the regulations -I would hope!

Might be worth me checking the neighbours 2 doors up from me (to address the 3-phase wiring).


Cheers,

Andy.

 

[felix]

Simple question. If you turn off your TV at the wall switch, does the screen go blue just before the thing goes off? I ask that merely to eliminate the blue screen clue from the enquiry.

This all sounds like a brown-out; a momentary voltage DROP. We know it's not a surge because the anti-surge extension didn't stop it (unless that's faulty of course). The RCD test might pick it up but here's another, free test. Flip the TV's wall switch off and on again as fast as you can. Does the TV come back on or drop into standby? What about the amplifier? If you can't simulate the fault this way I think you can eliminate brown-out - unless you've got the fastest switch finger in the West!

You say your lights don't go dim but that's an unreliable test because they'll be on a different circuit. Plug a wall lamp into the ring and see if that flickers when the fault happens.

 

[andyb32]

I've already tried switching the TV to standby mode, and the screen went black straight away, but I can try switching it off at the wall socket, and back on again straight away just to eliminate that from being the cause.

I take it that when I return power to the TV/amplifier, I am expecting it to come back on again? I think that Sony TV's (mine is a Sony) automatically go into standby mode though -if the power is switched off and then resumed (that is normal standby mode without the LED pulsating).

I'll also try plugging in a table lamp into the wall next to the TV/amp, to see if it goes dim at the point when the relevant appliance cuts out.

I am really worried though that it might be a mobile phone mast causing this (EMI), and what the potential effects could be on my health! -Especially if it's a 3G one, because even less is understood about the effects they could have on nearby residents.

I do have a TV aerial guy calling round next week though, so he may well be able to detect some interference if that is the cause.


Cheers,

Andy.