TV signal dies when a light is turned on - stumped! (1 Viewer)

[The Lobster]

I'm getting a problem with my TV - any ideas to diagnose/fix it? It works fine and picks up all expected freeview channels (including the HD ones)... until some of the interior lights are turned on. Depending on which ones are turned on the signal either disappears completely, or reduces enough to cause occasional picture drop-out.

• I've checked the TV on both 12v and 240v, and on different sockets - no difference.
• It works fine on other sources (e.g. DVD or USB), and fine if I take it into the house and try it on Freeview or satellite.
• Inserting an "earth break" aerial connector makes no difference.
• The signal booster was fitted by a previous owner and is spliced into existing wiring - if I disconnect the signal booster power lead this makes no difference.
• Removing the separate signal booster (and just connecting the aerial directly to the TV via an inline aerial connector) makes no difference.
• The aerial and aerial cabling signal or shield is showing no shorts and no voltage against earth, whether the lights are on or not.

However I'm still thinking that this might be some sort of earthing problem - if I simply touch/hold the aerial cable near the aerial (even on an insulated area) the signal is restored - although not if I try that near the TV.

Stumped!

 

[Barclaybasher]

Had a problem with my tv, sound would go off if I used a tap,

cause..... leisure battery going flat

 

[hilldweller]

Are the lights LED ?

Some kick out electrical noise that could be the problem.

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[Flamenca]

Are the lights you switch on fluorescent? If so they might be feeding interference back into the 12 volt circuit.

 

[DBK]

Are the lights LED ?

Some kick out electrical noise that could be the problem.

Are the lights you switch on fluorescent? If so they might be feeding interference back into the 12 volt circuit.

I would have thought it was something like that. It might be possible to fit a suppressor across the inlet terminals to the lights which cause the problem. You may have to disconnect the lights first then reconnect them one by one until you can isolate the one causing the problem. Then either replace it, it may be about to fail anyway, or fit a suppressor. Car accessory shops should sell them though they will probably be big.

 

[The Lobster]

Are the lights LED ?

Some kick out electrical noise that could be the problem.

Yes they are - I did a test by swapping one back to the old halogen bulb and the problem wasn't present! I monitored the TV signal strength with halogen vs LED and could see a very marked difference... this would also explain why putting my hand near the LED bulb reduced the interference. I also re-discovered how hot halogen bulbs get - ouch!

Full marks for diagnosing the issue within seconds of me posting... now I'm wondering what to do about it. A judiciously placed ferrite bead? Hope I don't have to replace all the LED bulbs... perhaps a little 1.5nF capacitor across their legs might help. Might try that.

From what I understand these small LED bulbs typically require a switching current regulator (which causes the interference) but do not include radio interference suppression components because of the package size... although apparently some bulbs use a "linear" regulator (no switching so no radio noise)... but I can't find any

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[The Lobster]

So now that I start searching for "interference from LED bulbs" it's clear that this is a major issue with the technology - and yet I never spotted it before replacing the halogens in my MH, which is annoying. It also appears to be difficult to identify which LED bulbs will cause interefence, and which won't - this doesn't necessarily appear to be price related, for example. Super!

 

[hilldweller]

although apparently some bulbs use a "linear" regulator (no switching so no radio noise)...

Yes they use resistors to regulate the current. Any advertised 8..24V will be switch mode. Something like 12..15V will be resistors and cheaper.

 

[Lenny HB]

Yes they are - I did a test by swapping one back to the old halogen bulb and the problem wasn't present! I monitored the TV signal strength with halogen vs LED and could see a very marked difference... this would also explain why putting my hand near the LED bulb reduced the interference. I also re-discovered how hot halogen bulbs get - ouch!

Full marks for diagnosing the issue within seconds of me posting... now I'm wondering what to do about it. A judiciously placed ferrite bead? Hope I don't have to replace all the LED bulbs... perhaps a little 1.5nF capacitor across their legs might help. Might try that.

From what I understand these small LED bulbs typically require a switching current regulator (which causes the interference) but do not include radio interference suppression components because of the package size... although apparently some bulbs use a "linear" regulator (no switching so no radio noise)... but I can't find any

The cap may work might be easier to fit a ferrite core on the TV power lead if it hasn't already got one.

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[The Lobster]

Yes they use resistors to regulate the current. Any advertised 8..24V will be switch mode. Something like 12..15V will be resistors and cheaper.

They were all advertised as 12V only un-dimmable... looking at the adverts again gives no indication at all as to the regulator type.

 

[The Lobster]

I

The cap may work might be easier to fit a ferrite core on the TV power lead if it hasn't already got one.

I've got some clip-on ferrite cores coming tomorrow - I'll try them at both ends...

 

[hilldweller]

I've got some clip-on ferrite cores coming tomorrow - I'll try them at both ends...

Worth a try and cheap.

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[Don Quixote]

If your 12volt cable from the TV to the supply socket is very long this can acted as an aerial. Try making the cable as short as possible or at least less than 3 feet or 1 metre. Ferrite cores may work, but make sure they are coiled (cable) a few times around the core. Good luck

 

[WillH]

We have a digital radio in the kitchen at home and it is very sensitive to our led lights. I suspect that this may be a problem.

 

[The Lobster]

So, results so far: the TV already had a ferrite core in it's power lead, so adding one there made no difference. Adding clip-on ferrite cores to the smaller (G4) bulbs solved the problem completely for them However the bigger MR16s weren't fixed by this - possibly because I can't position the ferrite cores as close to the bulbs. I have some small capacity capacitors on order, so I'll try those instead when they arrive.

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[The Lobster]

We have a digital radio in the kitchen at home and it is very sensitive to our led lights. I suspect that this may be a problem.

If you read the threads around the web regarding "interference from LED bulbs", most refer to problems with DAB and LED down-lighters

 

[Don Quixote]

Well I have both DAB and TV running fine without problems and the MH is full LED'd which I fitted 90% myself, must be very lucky.

 

[SuperMike]

As already, mentioned it seems that it is simply down to the quality of the LED's and their associated circuitry. Were they cheap ones like those sold on Ebay ? If so, I would not fiddle around with them, take them out and put in decent ones, like from Aten Lighting.

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[tonyidle]

As already, mentioned it seems that it is simply down to the quality of the LED's and their associated circuitry. Were they cheap ones like those sold on Ebay ? If so, I would not fiddle around with them, take them out and put in decent ones, like from Aten Lighting.

It may be that the 'decent' ones, that have regulators, are the cause. LEDs on their own do not cause interference. Switching regulators can and do. My van is full of Chinese eBay LEDs that have no effect on either DAB or TV. Two failures so far out of 16 modules installed.

 

[SuperMike]

It may be that the 'decent' ones, that have regulators, are the cause. LEDs on their own do not cause interference. Switching regulators can and do. My van is full of Chinese eBay LEDs that have no effect on either DAB or TV. Two failures so far out of 16 modules installed.

Perhaps you are right, but it would be worth changing one to see what happens. Just an idea. Aten Lighting, no failures so far out of 33 modules installed.

 

[The Lobster]

Perhaps you are right, but it would be worth changing one to see what happens. Just an idea. Aten Lighting, no failures so far out of 33 modules installed.

From other threads there doesn't seem to be a strong correlation between price and level of RFI --- more to do with design. You can pay a lot for bad design! Unfortunately you can't tell from the info given on the adverts, so recommendation is the best way forward IMHO. I'll give Aten Lighting a go...

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[mitzimad]

we have a similar problem when i plug the phone into a wired usb socket the dab radio sound goes any suggestions i assumed they may be on the same circuit and voltage drops

 

[Jaws]

Re telly interference .. I would try a 1000 pF capacitor across the light sockets first..

 

[tonyidle]

we have a similar problem when i plug the phone into a wired usb socket the dab radio sound goes any suggestions i assumed they may be on the same circuit and voltage drops

Interference again. The socket uses a switching regulator so the same suppression methods apply.

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[bubble63]

I had exactly this problem last year, DAB radio completely debilitated by them, TV only at night !!
You can easily tell which bulbs are the cause, by trail and error
They came from the supplier at the peterborough show, he sells from the cattle shed and has the most stock,in a gazebo. Took them back, he denied they had ever had a problem
different supplier , no probs

 

[The Lobster]

So I received some "test" bulbs that I bought from Aten and they worked fine, not causing any interference. However... the G4 bulbs were really large diameter and didn't fit my down-lighters without some "adjustment" to the reflector (we have a Bürstner). They now just fit in - but quite a squeeze as they are also very long. I assume that as they are such large bulbs they have the space to fit a suppressor... my last test will be using tiny capacitors soldered to the offending bulb leads, but these haven't arrived yet...

 

[The Lobster]

So I received some "test" bulbs that I bought from Aten and they worked fine, not causing any interference. However... the G4 bulbs were really large diameter and didn't fit my down-lighters without some "adjustment" to the reflector (we have a Bürstner). They now just fit in - but quite a squeeze as they are also very long. I assume that as they are such large bulbs they have the space to fit a suppressor... my last test will be using tiny capacitors soldered to the offending bulb leads, but these haven't arrived yet...

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[The Lobster]

If I could work out how to delete a post I'd remove that duplicate...

 

[DavidG58]

If I could work out how to delete a post I'd remove that duplicate...

you cant delete a post, that facility went some time ago, helps to keep up the post numbers , only seems to happen to me when we have very low internet signal or I have been drinking

 

[bubble63]

Alten bulbs have been fine.
People in Derby had the issues

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