Static interferance on tv's

[palehorse89]

When the refg./freezer in the basement kicks on in the ac mode all the tv's (3 of them) get interferance on them. When I go out and unplug the refg./freezer the static interferance goes away and it is now running on the 12 vdc side. Any ideas on what I can install or do to fix this problem?

[KSCRUDE]

Are these the old box type tvs or the new flat screens? Might try a new flat screen in the coach and just plug it in to power and ant. And see if it makes a difference. May still do it , who knows without trying. There may be a problem with the freezer as it does it on AC and not on DC.

[wa8yxm]

What is the make and model of the fridge? Some refrigerators have serious control board issues with FCC part 15 (Whichi is to say the cause radio frequency interfernece.

Another possible cause is a loose screw, I've found many RVers have a few screws loose,,, When it's the screw that holds an electrical wire, like the ones in your breaker box.. When current is drawn arcing can happen and that too casuses Radio (And television) Interference.

A hand held AM radio can help find he problem.

Also, if you power the fridge off an inverter... MSW epically.

[palehorse89]

It is a dometic basement model on slide rails, and no it plugs into a basement outlet and when no shore power it runs off 12 vdc. I will see what I have to do to check the connections. No inverter. I do not remember this doing it a year ago it is something that has started in the past year or so, good advice in using a a/m radio. Thank you

[VanDiemen23]

I'd check the chassis ground on the TV and the circuit as well. I haven't had a TV since the 80's that was affected by ANY power line interference - the power supply filters are that good. I guess if you have a piece of equipment somewhere with a DC-CD converter running @ 15KHz or so you would see that in the video, but I still have to think it's a bad ground somewhere.

[Libero]

The AM radio is a good idea that may help to isolate spurious RV emissions if you do not have access to more precise instruments. Interference can also be carried on power lines so checking with an oscilloscope might help in this regard if you have ruled out RF radiated sources. Batteries are very good filters but it is possible to get spurious line interference.

Below are some thoughts and actions you might wish to consider, look at or try:

You note "static interference" on your TV 's. Is that both audio and video interference?

Is the interference there when playing a DVD or when some source other than RF is used?

Is the interference there when you remove anything connected to the TV antenna/RF input?

If you put a short on the TV RF input, is the noise still there?

As others have said, bad connections can often be a problem source but I have never seen a direct Chassis Ground connection on TV,s. Other than direct 12Dc powered units, TV,s. are fed by 2 wire ac lines or by a 2 wire DC line from a power brick. (no ground wire) TV.s that operate direct off the battery would have one side grounded to chassis of course through the power connection.

Good luck, please post the solution.

[palehorse89]

Originally Posted by Libero

The AM radio is a good idea that may help to isolate spurious RV emissions if you do not have access to more precise instruments. Interference can also be carried on power lines so checking with an oscilloscope might help in this regard if you have ruled out RF radiated sources. Batteries are very good filters but it is possible to get spurious line interference.

Below are some thoughts and actions you might wish to consider, look at or try:

You note "static interference" on your TV 's. Is that both audio and video interference?



Is the interference there when you remove anything connected to the TV antenna/RF input?

If you put a short on the TV RF input, is the noise still there?

As others have said, bad connections can often be a problem source but I have never seen a direct Chassis Ground connection on TV,s. Other than direct 12Dc powered units, TV,s. are fed by 2 wire ac lines or by a 2 wire DC line from a power brick. (no ground wire) TV.s that operate direct off the battery would have one side grounded to chassis of course through the power connection.

Good luck, please post the solution.

Is the interference there when playing a DVD or when some source other than RF is used?
1. just interferance on video
2. I dont remember, I dont think so
3.how do I short the rf input?

[Libero]

To short out the RF input Just take a paper clip or safety pin etc and connect the center pin on the coaxial connector to the outer casing of the RF input on the TV. This is a bit of shot in the dark, but if the interference is still there when the RF input is shorted out the interference is more likely being introduced through the power source. (but not necessarily - depending on the TV,s design.)

I believe you mentioned your Freezer operates on 120vac by default when this power source is available, and there is no inteference when in this mode. Am I correct on this?

Another test you might try is connecting your freezer to an independent DC source such as a battery not connected to the RV house batteries. You could just run a jumper from your car etc for example to your freezer DC input while it is disconnected from all RV electrical sources and see if the interference goes away.

This won't fix the problem, but it will help to isolate the source.

A quick note or phone call to the freezer manufacturer might be worthwhile also.

I would not rule a bad connection somewhere though as others have noted. This is often a source of a problem. Suggest you undo and clean all physical connections. Even a small amount of corrosion can cause electrical interference.

I have no experience with these freezers so my opinions and suggestions are soley based on my training and experience on other systems. I would use an oscilloscope on the DC line to see if it was clean, but most people don't likely have one sitting around. I have one and use it when I tinker with electronic systems.

Hope I was able to help. Please post your findings and eventual fix solution. Good luck.

[Wayne M]

Worth a try is going t an electronics store and asking for a toroid core, even a couple. You would make several of the TV electrical cord wraps around the toroid (usually a hole in the toroid to do this) and then plug it in. Increase or decrease the number of turns of the electrical cord. Do this near the end that plus into the TV.

The above would be for an electrical source distributing down the ac line.

For RFI (Radio Frequency Interference) explain to the electronics store manager (he knows more) your problem and ask if he has an RFI Filter. You may be able to look that up on-line and make one.

Eliminating or fixing the source would be the best method, but may be to expensive.

[palehorse89]

QUOTE:
I believe you mentioned your Freezer operates on 120vac by default when this power source is available, and there is no inteference when in this mode. Am I correct on this?


No, the other way around, when I unplug from the 120vac the static goes away. I am going to take the ideas that have been posted and see if I can figure it out. First thing is to plug it into a outlet in the garage and see what happens and then go on from there. I will let you all know what happens along the way.

[Libero]

Thanks.

Sorry I misunderstood the circumstance, It makes more sense that the interference would come from an AC source vs DC that have batteries on the line. Batteries make very good line filters but bad connections can cause spurious emissions.

Good luck,

[chuckinthebus]

Does this interference move horizontally up or down on the screen and continue to move? This only happens when outside freezer compressor comes on or continuously while running? Check the ground where freezer plugs in.
Home Depot or similar will have one of these .

[palehorse89]

Originally Posted by cnkinthebus

Does this interference move horizontally up or down on the screen and continue to move? This only happens when outside freezer compressor comes on or continuously while running? Check the ground where freezer plugs in.
Home Depot or similar will have one of these .

Hello, just static, no movement, and has static the entire time the compressor in the fridg.is running. While it is running if I unplug it tv is clear.
I have one of those outlet testers in my garage, I did not think to use it, I'll try it and see what lights up.

[Gary - K7GLD]

Worse static generator in both our RV's are the bathroom vent fans - THOSE suckers can really disturb the TV picture, but no big deal, since they aren't used a lot...

DC motors can be bad RFI generators because of the motor brushes arcing when operating,...