Univolt HUMMING!

[markparker22]

I have a 1984 Excella and the original Univolt system has a noticeable hum when connected to the 110V AC that bothers me. Is this normal or is this a result of aging parts, like capacitors or the transformer?

[67caravel]

My '67 hummed. I don't think it is something to worry too much about...

[71tradewind]

The reason your Univolt hums is because the varnish in the transformer has become brittle and allows the plates of steel to viberate causing the noise u hear.Its really more annoying than anything,You can take it apart and re-coat the transformer with varnish it if becomes too annoying.

[markparker22]

Thank you Tradewind for that advice.

[87MH]

Originally Posted by 71tradewind

The reason your Univolt hums is because the varnish in the transformer has become brittle and allows the plates of steel to viberate causing the noise u hear.Its really more annoying than anything,You can take it apart and re-coat the transformer with varnish it if becomes too annoying.

Has anyone actually done this?

Did it work?

In hindsight, would you do it again?

[Janets Husband]

Your Univolt hums because it is a ferro-resonate charger. The technology is very old. I have worked on this type of charger that dates back to the early 40's. They hum is because the circuit sets up the transformer in resonance, hence; ferro (iron core) resonance.
If you want quiet you will have to go the the newer switched mode supply which raises the resonate frequency up in to about the 200kHz frequency range where you can't hear the components ring.
Another advantage to changing out your old Univolt is the newer chargers have multiple charge modes which help to take better care of your battery banks. (Last Longer)
I changed mine out and am happy as a clam that I did. Quiet, and my battery does not boil dry.

[TomW]

Originally Posted by 87MH

Has anyone actually done this?

Did it work?

In hindsight, would you do it again?

I have not done this, but the idea has merit. But, between what I understand about transformers, and what I have read about Univolts in general, there will always be a hum.

I believe the individual plates which make up a transformer's core are "varnished" before assembly. Disassembly will be a chore. IMO, the amount of hum reduction would probably not offset the labor involved to perform the task.

Tom

[Ken J]

On my 75, during the day I really don't notice it, at night I turn if off.

Ken

[markparker22]

Here is a link to Inteli-Power 9100 Converters which has a link to a lay-man's tutorial on the various types of converters:

http://www.progressivedyn.com/rv_power_converters.html

[drivo]

Gary
Read your thread with interest. Just purchased a 1976 Tradewind and was wondering about the hum. What newer units do you recommend and is it a difficult task to replace it?

Thanks for your time

Ivo

it is a ferro-resonate charger. The technology is very old. I have worked on this type of charger that dates back to the early 40's. They hum is because the circuit sets up the transformer in resonance, hence; ferro (iron core) resonance.
If you want quiet you will have to go the the newer switched mode supply which raises the resonate frequency up in to about the 200kHz frequency range where you can't hear the components ring.
Another advantage to changing out your old Univolt is the newer chargers have multiple charge modes which help to take better care of your battery banks. (Last Longer)
I changed mine out and am happy as a clam that I did. Quiet, and my battery does not boil dry.[/QUOTE]

[TomW]

Originally Posted by drivo

...and is it a difficult task to replace it?

It is an easy, wire-for-wire replacement. Many people will probably offer a much better, care-free replacement.

I, on the other hand, am someone who would milk the cow in the morning for fresh milk. I enjoy the challenge of running the Univolt while not overcharging the battery.

Just another point of view,
Tom

[john hd]

they hum 'cuz they can't sing!

john

[Kistler]

Mine hums sometimes.....I thought the thing had a fan and cooled itself off once in a while.

[RivetED]

I guess you now have an Airstream & a hummer!

[guy99]

Originally Posted by markparker22

Here is a link to Inteli-Power 9100 Converters which has a link to a lay-man's tutorial on the various types of converters:

http://www.progressivedyn.com/rv_power_converters.html

Airstream is using now? If they're still using the UNIVOLT does anyone know why?

[JohnG]

Mine hums too. Funny how you really don't notice things like that during the day but thay become an annoyance at night.
During the day other noises fill the air and in effect they drown out the ever-present hum of the Univolt.
What's the solution that we can all live with? I turn on the radio at night to a station that plays soft music without too many interuptions or put on a CD.
Once asleep that hum has no effect...............................

[ALANSD]

We run our fan at night, the one in the bathroom. It covers any univolt noises.

[markdoane]

Originally Posted by guy99

Airstream is using now? If they're still using the UNIVOLT does anyone know why?

All the new units I saw at the show last year had Parallax converters.
http://www.parallaxpower.com/

[Janets Husband]

e

Originally Posted by drivo

Gary
Read your thread with interest. Just purchased a 1976 Tradewind and was wondering about the hum. What newer units do you recommend and is it a difficult task to replace it?

Thanks for your time

Ivo

It is not difficult to replace an old Univolt with the newer switched mode style chargers. One for one swap in my book, but I work with it every day. A little thought and anyone should be able to perform the replacement.
I used the Intellipower 9100 with the Charge Wizard, 65amps of smart charging.
Go to their web site and look around.

It is stone quiet unless the fan is on and the fan only comes on under very high load situations.

I noticed others have said their Switched Mode Chargers are making noise. If so, they should have it looked at. The only thing you should hear is the fan.