Virgin Media Engineer - gawd bless em

[Robojin]

A friend called me up said that their TV in Kitchen was doing weird things, basically randomly changing the V-Box channels, that they had Virgin engineer (hmmm) come round swap out the box and this seemed at first to solve it.

So... I get this call as my friend is concerned, because the problem was back and didn't know what to do next, and since AV was my thing (as well as electrics) perhaps I could help, she also enlightened me to one of the comments from the engineer that had worried her. This had me ROTFWL , this dope explained that he had heard that this might be down to a fault on the earth side (e.g electrial) and she might need to get the electrics checked.

After I'd picked myself up, I explained that he was talking utter bol&*ks, since the V-Box had no earth path and was two core mains plug, as was the TV. So I popped round, plugged in my kewtech fault tester in to the local DGSS to show as expected no fault (cpc present).

Then went about seeing if I could explain what was going on, checked the remote for sticky buttons (e.g. Ch+/-), clearly no prob here, and all was behaving normally. As I left and walked passed the TV, the V-Box did it's mental channel and menu changing, and after a while I could get it to do this almost on demand.

The fault is quite simple (and nothing to do with a missing earth), the TV is an LCD/LED, the V-Box IR reciever is based on LED tech, so anyone walking within a foot or so of the screen is reflecting the light from the TV back at the V-Box IR, the random nature is down to the fluctuations in brightness, being interpreted by the box as differing commands, the box will often continue for a while, sometimes needing a complete reset.

I've covered the sender temporally with a moveable barrier (so they can move to change ch) and told them to give me feedback after a week.

I'm aware of issues of Plasma output messing with IR, but had never seen it in the wild, just one of those odd ones you might get and need to solve

 

[steptoe]

:slap

well I never,

have seen similar things before, but never the tv being 'reflected' back at the sensor.!!!

 

[Andy™]

ive never heard of that happening either!

 

[Robojin]

It surprised me, but as I said there are known issue with Plasma output messing things up with IR, and if you think about it, IR is just light at a different wavelength, so it may be that some of the light output from LCD/LED is also outside visible spectrum.

I was watching a BBC prog that talked about the blue light from LCD computer screens can effect your circadian rhythm, e.g. not good before you go to bed

 

[galaxy]

A friend called me up said that their TV in Kitchen was doing weird things, basically randomly changing the V-Box channels, that they had Virgin engineer (hmmm) come round swap out the box and this seemed at first to solve it. So... I get this call as my friend is concerned, because the problem was back and didn't know what to do next, and since AV was my thing (as well as electrics) perhaps I could help, she also enlightened me to one of the comments from the engineer that had worried her. This had me ROTFWL , this dope explained that he had heard that this might be down to a fault on the earth side (e.g electrial) and she might need to get the electrics checked.

After I'd picked myself up, I explained that he was talking utter bol&*ks, since the V-Box had no earth path and was two core mains plug, as was the TV. So I popped round, plugged in my kewtech fault tester in to the local DGSS to show as expected no fault (cpc present).

Then went about seeing if I could explain what was going on, checked the remote for sticky buttons (e.g. Ch+/-), clearly no prob here, and all was behaving normally. As I left and walked passed the TV, the V-Box did it's mental channel and menu changing, and after a while I could get it to do this almost on demand.

The fault is quite simple (and nothing to do with a missing earth), the TV is an LCD/LED, the V-Box IR reciever is based on LED tech, so anyone walking within a foot or so of the screen is reflecting the light from the TV back at the V-Box IR, the random nature is down to the fluctuations in brightness, being interpreted by the box as differing commands, the box will often continue for a while, sometimes needing a complete reset.

I've covered the sender temporally with a moveable barrier (so they can move to change ch) and told them to give me feedback after a week.

I'm aware of issues of Plasma output messing with IR, but had never seen it in the wild, just one of those odd ones you might get and need to solve

thats not quite correct,virgin tv box's have a problem with energy lamps,i get this problem all the time with virgin tv in my house be it 240v lamps or 12 v lamps,the box locks out on a command screen saying press ok you have to restart it and switch the lamps off,its a pain..

 

[Robojin]

thats not quite correct,virgin tv box's have a problem with energy lamps,i get this problem all the time with virgin tv in my house be it 240v lamps or 12 v lamps,the box locks out on a command screen saying press ok you have to restart it and switch the lamps off,its a pain..

Eh? no it's very correct, but yes it's my hypothesis in regard to this particular installation, the channels and menu randomly change only when there is a close by surface for the TV to reflect off, there were no lights on at the time as it was daylight, your installation may have an emitted light related sensitivity problem e.g. the box IR is sensitive to certain wavelengths of light.

 

[galaxy]

Eh? no it's very correct, but yes it's my hypothesis in regard to this particular installation, the channels and menu randomly change only when there is a close by surface for the TV to reflect off, there were no lights on at the time as it was daylight, your installation may have an emitted light related sensitivity problem e.g. the box IR is sensitive to certain wavelengths of light.

that maybe so,all my vtv problems arise at night when lights are on,its a known problem with virgin tv,but if walking within a foot of a tv causes a problem this would bring problems to far more people,im not aware the body reflects ir more absorbs it,my vtv does this around twice a week,surely mr branson could come up with a fix..

 

[Robojin]

that maybe so,all my vtv problems arise at night when lights are on,its a known problem with virgin tv,but if walking within a foot of a tv causes a problem this would bring problems to far more people,im not aware the body reflects ir more absorbs it,my vtv does this around twice a week,surely mr branson could come up with a fix..

It was a surprise to me I'd have thought the same, but if you think about it, light (particularly IR) will bounce of any surface, some materials absorb more of the light (or wavelengths) than others so it's all very feasible, and in this case can be repeated time after time. Perhaps we have a member with a PhD in Particle Physics who could explain the detail

It's possible that it has happened to others, in this situation it just happens that the TV is close to to Kitchen door and is in effect a walkway to the main part of the Kitchen

 

[galaxy]

It was a surprise to me I'd have thought the same, but if you think about it, light (particularly IR) will bounce of any surface, some materials absorb more of the light (or wavelengths) than others so it's all very feasible, and in this case can be repeated time after time. Perhaps we have a member with a PhD in Particle Physics who could explain the detail

from ge lighting,philips say the same,as do virgin tv,which annoys the hell out of me,whats the point of having energy lamps that were told to have to save the world when you cant watch tv,granted its rare as they say but it happens to me...and loads of others..i see a baby boom coming.. :x

ge.

Can compact fluorescent bulbs create interference with electronic equipment, such as radios?

Many electronic devices, such as radios, televisions, wireless telephones, and remote controls, use infrared light to transmit signals. Infrequently, these types of electronic devices accidentally interpret the infrared light coming from a compact fluorescent bulb as a signal, causing the electronic device to temporarily malfunction or stop working. (For example, your television might suddenly change channels.) Fortunately, this only happens when light is produced at the same wavelength as the electronic device signals, which is rare.

To reduce the chance of interference, avoid placing compact fluorescent bulbs near these kinds of electronic devices. If interference occurs, move the bulb away from the electronic device, or plug either the light fixture or the electronic device into a different outlet.

 

[steptoe]

plug either the light fixture or the electronic device into a different outlet.

:slap

and thats going to stop the ir light,

 

[Sidewinder]

Steps,

No it won't stop it but, it "could" change the frequency enough to move it from the interference band.

 

[steptoe]

even on the same phase?

or are you saying it 'may' hit the wave at a slightly different point?

a bit beyond me this sort of stuff.

 

[Sidewinder]

Yes mate even on the same phase.

You are talking about quite subtle phase shifts and the inductance and capacitance of the cabling between the 2 different outlets could shift the f enough to remove the issue.

 

[Robojin]

I think you will find that there is also a relationship between the wavelength of the IR emitted (periodically) from the TV to the distance of the reflective surface and back to the IR receiver on the V-Box (in my scenario), something along the lines of the harmonics you have with sound (another waveform), by moving the light emitting source (or receiver) you would change the harmonic (or frequency pattern) possibly wrong terminology, but you get the gist. My solution may be as simple as moving the V-Box back by a small amount which would alter the conditions therefore the resulting interference would cease.

I think my head hurts know

 

[Theorysparky]

:slap well I never,

have seen similar things before, but never the tv being 'reflected' back at the sensor.!!!

When i was with NTL 5 years ago things like this were common

Thomson tellys,,,,,florries all did weird things causing channel hopping

blaming the electrics is a fob off,,,,,,before i left we were issued with socket testers to ensure the supply to the kit was ok

before digital we used to get 'hum bars' which was electrical...........

 

[ProDave]

This is also a know issue with Sky HD boxes. Particularly Samsung Sky HD boxes and Samsung LCD tv's used together.

There, it's not so much a case of interfering with the IR sensor, but swamping it so nothing works.

My Mother (85 this year) had a fault on her tv. it was stuck on BBC2. No mater what she did, it went back to BBC2. My Sister who lives near went for a look and couldn't understand it, and phoned me as she thought "something was sending a signal"

Anyway after getting nowhere, mum went and bought new tv, identical to the faulty one. Unpacked it, tuned it in, only to find that too was stuck on BBC2.

Further investigation, found the "2" button of the original remote was stuck down, and that was still in the room with the new set.

 

[col]

Years ago we had a TV & could randomly change channels by rattling a bunch of keys.

No idea how, thought at the time maybe it was ultrasonic, it was in the early days of remote controls.

 

[ProDave]

Could well be.

I once had a tv with ultrasonic remote. I thought it was brilliant. Not directional at all (like IR) you could even change channel etc from the next room.

But then it did only have 8 channel buttons, volume up, volume down and on/off.

 

[col]

1980s - 4 channels but no repeats,

2012 - 400 channels repeating the same old stuff

Somebody shoot me, I'm turning into Jeremy Clarkson

 

[RB2004]

just like to correct here.. the box does have an earth path!

the metallic chassis of the box, is connected to the outer braid of the coax cable feeding it.. which in turn goes back to a pit or cabinet feeding every other house also connected to the outer braid via the splitters / taps.

Everything inside the green boxes are earthed.So

effectively it can go back to earth... not through the house, but through the green cabinets, linked via coax.

its actually a question ive been trying to find answer to.. because of how the coax drop cables are linked to other houses and their green boxes.. should the drop cable be equipotentially bonded back to the MET in the same way as the Gas and Electrics

a number of times I have disconnected the coax from the box and felt a tingle, and as you connect it sometimes you can see tiny blue arcs.. so theres definitely a potential difference there.