Discussion in 'Electronics & Electrics' started by WooKiE_MaN, Feb 26, 2008.
I should add that I believe its environmental as the interferance is worse when it is raining.
I had this problem. I got rid of it with a power supply Filter
what did u get? and on which devices did u put it on?
Dragging up a year old thread I know but no point in a new one for the same issues.
Did the OP solve his issues?
I have had these kind of issues for years now, being an early adopter and all, and I am yet to solve the issue.
We have nice strong signal ( Kellyville in Sydney North West) with a two story house so the antenna is nice and high, a 1 year old digital only antenna, and quad shielded coax throughout the house.
I am using quad shielded patch leads and everywhere is an f-type connector except for into the STB's.
Yesterday I got some LED downlights to see what they were light and to potentially reduce 90% of the lighting power consumption from our loungeroom.
The lights are OK, just. They are not nearly as bright, but you dont really need it that bright.
I got 4W 12V downlight replacement globes, replacing the 50W ones that were there.
OK so to the relevant issue.
Whenever a downlight is turned on that has the LED globe, the TV is totally unwatchable.
It 100% locks up ch 7 and 9.
Freezes the picture on the screen until such a time as you turn the light of then it comes back 100%.
There is no doubt that this is caused solely by the LED lights as it happens when they are turned on and goes away when they are off.
Has anyone else experienced such interference before?
At $30 a downlight globe it is an expensive issue if there is no solution.
At least I only got 4 globes, but I was going to bit the bullet and replace all 30 globes in the house. That would have sucked right about now if I did get them all.
I really dont think that digital tv in Australia has ever been properly thought through and refuse to accept that the it is standards fault.
If an old car drives down the street, or the guy across the road starts his boat, or someone mows their lawn, or if someone uses a power tool, we lose tv reception. This has happened in two different houses now so it isnt the setup.
It's got nothing to do with your LEDs. Either your antenna cables, fittings etc are far to close, and parallel to, mains wiring, or your STB is dodgy.
Ahh, no, it has EVERYTHING to do with the LEDS.
It is 100% repeatable and suffers total lockup whenever the LED downlights are switched on.
I am curious as to your assertion.
If you've managed to pin it down to something that happens only when the LEDs are on, the LEDs are incidental. They're a very low powered, low noise load. You're looking in the wrong place, and there's something else going on.
Halogen Downlights in use
Halogen bulbs replaced with LED bulbs
Interference on digital TV
How can that be incidental and I be looking in the wrong place?
There is nothing different between Situation 1 and 2 except the LED downlights.
If your mains, the downlight transformers, and the downlight sockets were all wired correctly, LED downlights could not physically cause the problem you're seeing. The problem, I say again, is elsewhere.
The LED fittings are producing line noise (probably in combination with the halogens electronic transformer) on your 240V which would be on the same/nearby circuit to the STB.
try plugging things into different house circuits
buy a 240v regulator - I would use this on the STB to avoid noise from other sources too
buy iron core transformers for the LEDs instead of electronic ones (check compatibility)
buy a quality 12v regulated power supply to replace transformer/s (may actually be quite a cheap option)
buy better lamps/use the old lamps/use fluoro (also noise on startup)
buy a STB with a high quality PSU/line filter circuit
try a cap upgrade on your STB
theres more on proper earthing of devices, the list goes on. Have a look at DTVforums too, tell us how you go.
If your getting interference in the antenna only when certain devices are turned on or off then the coax cable is running too close to a power cable. The other option is that one of the connections (behind the wall plate) is too close to a power point or power cable.
You need at least 50mm separation between the 240v cable and the coax (legal requirement) and 150mm separation between a coax face plate and power point (legal requirement). The exception to both of those is if there is a physical barrier between them.
Another possible interference is if the coax cable is running parellal to the power cable (even though it may be 50mm away).
You will need to inspect all of your coax cable to ensure it is adequately separated from the power.
Suspect you've got water ingress into a cable (probably coax), and/or moisture is providing an alternate intermittent connection somewhere...
Do your signal levels change much when it rains as well? If so then first thing I'd be suspicious of is your coax cabling.
These types of problems are often caused by the use of cheap coax.
Replace it with quad shield RG6 would be my first suggestion.
yep, an old thread
but still same problems here, not as bad as it used to be, but here and there it still happens
Nah, I'm good now.
Thanks for asking.
The area you need to look at is not so much the power supply side but actually the RF side. Sure the power supply does like to be clean but the issues is caused not but line pulse (surge) but actually the RF noise generated by arcing contacts and back-EMF from inductive loads (Fluro's, figdes and Microwaves). Sure you can place a good choke style filter on the mains but it isn't going to help the issue of induced RFI on the RF circuit (coax and antenna).
The best method is to actually improve your TV signal from the antenna to the point that the set-top-box )STB) doesnt need to add gain to the incomming RF and it can actually start attenuating the signal to push both the high drive and noise floor down.
You will find you don't have a strong signal and the STB is having to boost the received signal (and subsequent noise floor) to be useable. Unfortunately, it wont help if there is RF noise, especially if it's pulsed in nature.
I have given up in replying as I dont know who everyone is replying to.
I was the second OP that dredged the thread up, but the replies have had nothing to do with my issue.
Just incase people were replying to me...
without the LED downlight globes installed, with the halogen globes, I have no issues.
I can flick the lights on and off to my hearts content and get no interference whatsoever, so there is no issue with the antenna, the cabling, the power or the light circuits.
When I take the halogens out and put the led's in, it goes to hell in a handbasket. the TV picture actually totally locks up, freezes. No sound, no picture.
turn the lights off and back it comes perfect.
turn them back on and out it goes again.
The only thing that i can think of is that the downlights use electronic transformers that are somehow not compatible with the LED lights and are putting out some horrid electromagnetic RF interference. (although the led globe manufacturers tell me that that wont be the case)
I will put one of the trannys out on the weekend and replace it with an iron core one, see if that helps.
Is 'second OP' like 'slightly pregnant'?
I'd guess the LEDs are not providing enough load to prevent the PSU from oscillating.
Further - if you put several LEDs onto a single PSU (electronic transformer is a term arts students use), I'll bet you find no interference at all.
You answered your own question. You have a noise source so either control it or eliminate it.
Hence my post regarding noise floor.