converter buzzing...a little guidance appreciated

[fourboysdad]

Heyo gang. I have a 2010 jayco 26bh travel trailer. there is a distinct buzzing sound coming from the breaker panel. I don't believe it's the fan. Here is what I know:

1. When connected to shore power with no lights on, there is a buzzing noise.
2. When disconnected from shore power and drawing from battery with lights both on and off, no buzz.
3. When disconnected from shore power but connected to TV, no buzz.
4. The battery is topped off and fully charged and the multimeter shows 12 volts.
5. When connected to shore power, the outlets are at 120vac according to mister multimeter.

Here's where it gets weird:

6. When connected to shore power with no lights on, there is a buzzing noise which stops immediately when i turn a light on. That's the weird one for me.
7. When connected to shore power and I turn off the converter breaker, the buzzing immediately stops, but the lights still work so I'm assuming they draw directly from the battery if the converter is off?
8. I made sure the converter, when on, is distributing power by disconnecting the battery and checking the lights...they work.

Whew...all that to ask this: i'm thinking either my converter is damaged, or the breaker supplying its power is damaged. Am I on the right track?

btw...the converter is pretty hot to the touch when it's buzzing.
btw2...a few weeks back, we were at a festival and drew power from a large generator the festival brought in to power the rv section. I did not use a surge protector...hindsight is 20/20.

Anybody have thoughts? Thanks very much!

[MEXICOWANDERER]

Sounds like it's mad.

[Gene_Ginny]

Wayne Dohnal wrote:

MEXICOWANDERER wrote:


There are a hundred million variations possible when using the word "Buzz".

Exactly why I said "all sorts of noises" 🙂 I wouldn't describe any of what I hear as buzz. More like gurgling and fizzing, not very concise either.

True. To me it really sounds like an old tube type TV flyback transformer breaking down ... but how many people here have ever even worked on an old TV or even know what a high voltage flyback transformer is. Buzz seems generic enough so everyone understands, "all sorts of noises" also works.

You probably can get rid of "the noise" if you:
. Turn off the converter
. Disconnect the battery
. Open the converter
. Find the round donut shapped thing with heavy copper wire wrapped around it
. Squirt in enough silicone sealer to encapsulate the heavy copper wire
. Put it all back together and turn it on

[Wayne_Dohnal]

MEXICOWANDERER wrote:


There are a hundred million variations possible when using the word "Buzz".

Exactly why I said "all sorts of noises" 🙂 I wouldn't describe any of what I hear as buzz. More like gurgling and fizzing, not very concise either.

[MEXICOWANDERER]

Too little fact, far too much speculation.

There are a hundred million variations possible when using the word "Buzz". Frequency and loudness. No converter, no electronics likes it when temperatures get "hot". Uncomfortable to touch and maintain contact.

Time to do more serious investigation. Start off by finding out from the manufacturer WHEN that fan MUST be running.

IMHO

[DiscoStu]

I've got a PD4560 in my unit and it does the same thing. I agree it's annoying. In our last trailer you could never hear the converter unless the fan turned on, this one has the loud buzzing which goes away if some lights are turned on. If there is a way to fix it I would happily try it out. I mentioned it to the dealer and, not surprisingly, was told that this is normal.

[Gene_Ginny]

fourboysdad wrote:
...
6. When connected to shore power with no lights on, there is a buzzing noise which stops immediately when i turn a light on.
...

From what I have seen, that is normal with many switching mode converters. The key is, turning on a light causes the buzzing to stop. Many, like the Prgressive Dynamics 4000 series, will change frequency as a load is applied. The switching frequency is normally well above the audible frequency range but it can still cause the laminations in the output transformer to buzz and be heard. As the load changes so does the frquency and the laminations no longer resonate or "buzz".

The voltage at your battery seems normal.

[wa8yxm]

I believe the PD 4600 series is a switching converter, Thus it likely is not the source of the buzz, but the cooling fan that cools it MIGHT BE.

You got to pull it out without disconnecting to be sure.

There are older units that had transformers, Big, HEAVY transformers. and those, after so many years, buzz.. Annoying, but not a sign of defect.

[fourboysdad]

yup, it moves freely.

[rrupert]

fourboysdad wrote:
I rechecked the voltage this morning. the output leads on the converter were 13.7. The battery leads showed 13.2. I also verified that the supply breaker to the converter is working correctly.

[COLOR=]The converter fan doesn't run at all and I'm thinking it should. Might that be part of the problem?

If the battery is bad, is it possible that would make the converter work harder and more frequently to charge the battery?

I plan to disconnect the battery today and then take periodic readings to see if it's losing charge. I'll report back. Thanks for all the insights thus far. Sounds like I don't have a dangerous issue which is my main concern.

Thanks,
D

Did you check the fan/s to see if it is turning freely? If seized up I could see that it could buzz if it runs off of AC.

[fourboysdad]

I rechecked the voltage this morning. the output leads on the converter were 13.7. The battery leads showed 13.2. I also verified that the supply breaker to the converter is working correctly.

The converter fan doesn't run at all and I'm thinking it should. Might that be part of the problem?

If the battery is bad, is it possible that would make the converter work harder and more frequently to charge the battery?

I plan to disconnect the battery today and then take periodic readings to see if it's losing charge. I'll report back. Thanks for all the insights thus far. Sounds like I don't have a dangerous issue which is my main concern.

Thanks,
D

[Roadpilot]

I think the converter is going into discontinuous mode of operation at no load. With any reasonable load it's in continuous mode. Continuous mode is when the frequency of operation is fixed or at least stable. At no load though the output current gets so low that the converter has to skip pulses in order to maintain control over the output voltage. It's normal for many converters and not harmful. The only thing you could do is keep a little load on it.

My experience is that most time transformer buzzing is caused my the metal EI laminations vibrating. They try to minimize this by taping and gluing the laminations. But it usually occurs with heavier loads.

[cochise49]

Always had a 12v system buzz in our last rig. Reason I say 12v is that is was there even when not connected to AC and continued after replacing convertor twice. So, not the convertor. I always thought it was an isolator in the chassis battery compartment. It never caused problems. New rig...no buzz.

[rockhillmanor]

When mine started buzzing it was a blown capacitor. It managed to run with only one capacitor but it was boiling the batteries because it could no longer regulate the voltage. When we took it out the capacitor looked like someone shot it with a 22!

Check your output on the converter AND leave the meter on 'after' it reaches what the specs call for to see if it climbs or falls.

[WyoTraveler]

ScottG wrote:
Sounds like the metal laminations of the converters transformer are vibrating. An annoying but not dangerous condition that happens to xfmr's sometimes. the noise changes with items turned on because it changes the xfmr's load.
More troublesome is the battery voltage. 12V is rather low, is it really just 12V or is it more like 13.2 or more with the rv plugged in? If it's only 12.0 then the converter is shot.

Agree. This happens a lot. Mine also has a transformer buzz.