60 cycle feedback/Surround sound

figallegro · 10-20-2009, 02:45 PM

Whenever I use the surround sound with the television, I get a 60 cycle feedback. This is true whether using shore power or the generator. Any idea how to troubleshoot this? I thought about using a filter on the surround sound, but don't know where to try one.
Tony

lakewoodpaul · 10-20-2009, 07:46 PM

had a similar problem in my 03. I ended up adding a seperate ground from a coax connection. A good ground seems to be very important.

mrschwarz · 10-20-2009, 08:01 PM

Have you tried reversing the polarity of the 120v plug?

figallegro · 10-20-2009, 09:06 PM

Not sure what you mean by reversing the polarity of the 120V plug. Are you referring to a plug for the surround sound and if so where would it be?

figallegro · 10-20-2009, 09:07 PM

Lakewoodpaul;

What coax location did you ground?
Tony

Theberrys · 10-20-2009, 09:32 PM

This got rid of most of my 60HZ noise. It's cheep enough to give a try.
You may need some adapters to get to the 3.5 mm connectors.
Dick

PAC Audio SNI-1/3.5 Ground Loop Isolator & Noise Filter - eBay (item 200387348869 end time Oct-23-09 17:06:37 PDT)

SCVJeff · 10-20-2009, 10:13 PM

Technically speaking there is no such thing as 60Hz feedback, but I get the drift. You have a ground loop as mentioned above and it can be one of the biggest PITA's you've ever seen to chase it down, often being nothing more than a loose PC board screw in a piece of equipment. The ground loop isolator mentioned above is a band-aid, but it works and causes no problems down the road.

DAN L · 10-21-2009, 12:52 AM

Quote:

Originally Posted by figallegro

Whenever I use the surround sound with the television, I get a 60 cycle feedback. This is true whether using shore power or the generator. Any idea how to troubleshoot this? I thought about using a filter on the surround sound, but don't know where to try one.
Tony

on my moho, there is a "filter" laying loose on the bottom of the compartment behind the tv. when this object moved just right, i got the same noise.
i installed some velcro on the bottom of the compartment and on the filter to keep it positioned in a good place. this has been working fine for about 1.5 years. you may have to use a mirror to find this filter.

grtharris · 10-21-2009, 07:54 PM

I agree with DAN L, move the filter as far away from the TV has you can with out it hanging out.

lakewoodpaul · 10-21-2009, 08:16 PM

If you recently made any changes to your sound system ie tv converter box,try grounding that or your entertainment center switch box the more grounds the better.

wa8yxm · 10-21-2009, 08:21 PM

First, it's not feedback, it's somethign else.. Second. you said it only happens when you use the Surround sound WITH the TV,, May I safely assume that if you are playing a CD or the radio it does not happen?

If so.. See if you can re-arrange the TV and the Amplifier.. Move cables or such.. There is a component in the television which generates a very strong electro-magnetic field, I have seen this part take out computer disk drives in fact. In fact there are TWO such components though only only works when you first turn on a CRT television (Neither of these parts exist on a LCD simular)

As I recall. (And this is very old memory) it is normally on the left side (As you look at the TV) near the rear. IT's called the Flyback trnasformer.. Off this device comes the high voltage lead to the CRT

The solution is to get the other stuff away from it

Cables, Amplifiers and such

Theberrys · 10-21-2009, 09:32 PM

wa8yxm is correct if your TV is a Glass tube. The flyback transformer creates the anode voltage, as high as 20K volts, for the CRT. The other device is the degaussing coil that is energized for a few milsec. at startup to remove any magnetism from the CRT, this is unlikely to be your problem unless the thermistor that controls it has failed. But you'd know right away as the picture would be distorted.

Dick

figallegro · 10-22-2009, 06:28 AM

Thanks for your help. I moved some of the wires around that are behind the TV and it stopped the noise. What a great site for getting a problem resolved.