Hum in the ZX700

poodlepeople · 09-23-2010, 12:49 PM

I have had my trailer and ZX700 for about 9 months and had no problems until yesterday. I tried to use the radio and found a strong hum (60 cycles in my experience) not just on the radio function but all functions. I disconnected the AC power at the park where we are staying and the hum goes away. I will test this at the next park but does anyone have an idea what is happening? Is this a new failure or just something with the shore power at this park?

**Bob Fields** · 09-25-2010, 07:43 AM

I will ask the techs what they think.

Emptypockets · 09-25-2010, 08:44 AM

I had the same hum you describe when plugged into shore power. To fix it I bought two separate chokes & installed one on the power wire & one on the coax. Problem fixed! Total cost $8.88 at Radio Shack.

poodlepeople · 09-25-2010, 04:43 PM

Yeah, it occurred to me that the problem may not be with the radio but possibly the converter or something that is allowing 60 Hertz to get into the DC circuit at a level that the radio (actually its stuff that drives the speakers) can't deal with - thus hum.

Where/how exactly did you install the chokes on both the shore power line and the coax (I assume the external TV connection)?

I am going to try the situation with the shore power at the next park along our route and see if it makes any difference. I will also contact technical support for both Concertone and for the converter to see if anyone has anything to say.

Emptypockets · 09-25-2010, 06:19 PM

Quote:

Originally Posted by poodlepeople

Yeah, it occurred to me that the problem may not be with the radio but possibly the converter or something that is allowing 60 Hertz to get into the DC circuit at a level that the radio (actually its stuff that drives the speakers) can't deal with - thus hum.

Where/how exactly did you install the chokes on both the shore power line and the coax (I assume the external TV connection)?

I am going to try the situation with the shore power at the next park along our route and see if it makes any difference. I will also contact technical support for both Concertone and for the converter to see if anyone has anything to say.

Yes, the one on the coax it the one that runs from the antenna to the radio. Go to Radio Shack & ask for suppressors & or chokes. The are made to open up & form around the power wire & coax. To me the inside material looks like it is carbon like you see in lead pencils.

I don't have the parts numbers however if you look at my profile & go to my statistic's then look for post started by Emptypockets if you go back far enough you will see where I posted a full report on what I did.

revrnd · 09-25-2010, 08:42 PM

Here's the thread w/ the PNs:

http://www.forestriverforums.com/for...date-6539.html

poodlepeople · 09-28-2010, 11:26 PM

At our next stop there was no hum! I got a response from the converter manufacturer (of course no word from Concertone!) and there is suggestion that poorly conditioner AC power could be the problem in the park where I first found the hum.

Does anyone understand this? I understand a power conditioner is valuable because of voltage drops and fluctuations but could this be responsible for hum in a DC powered radio?

yvesm · 09-29-2010, 06:11 AM

Our concertone hums all the time, we don't use it.

Emptypockets · 09-29-2010, 09:34 AM

Quote:

Originally Posted by yvesm

Our concertone hums all the time, we don't use it.

Does your Concertone have a hum in it when you are not plugged into shore power? That is how if figured out what was causing my hum - one day with no electric service I turned the radio on & it didn't have any hum.

yvesm · 09-29-2010, 10:17 AM

Battery or shore power, it hums. Something I will take out this winter and work on. The concertone is not a show stopper on our 2011 Rockwood, its all the other stuff that needs repair

**Bob Fields** · 09-30-2010, 08:13 AM

Quote:

Originally Posted by yvesm

Our concertone hums all the time, we don't use it.

Have you had the wiring checked for proper connections? A bad ground may cause this. While you are at it, you should double check all the wiring including the quality of connections.

Lastly, as seen on other threads this could also be caused by several other electrical systems that puts a "hum" on the entire electrical system (which is in turned picked up and played by the Concertone). There are several suggestions for installing NOISE FILTERS which have solved the problem.

Let me know if you have any specific questions and what ends up solving the problem.

OR if there is still a problem after all the above.

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