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 > Transfer switch buzzing

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cm2785

So Cal

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Posted: 02/13/18 11:16am Link  |  Quote  |  Print  |  Notify Moderator

Hey guys I have a 96 Bounder 34j with 11k miles and it has a PowerTek PDC-1001 distribution box. I have already read that the transfer switch is attached to the back of the box. When I am plugged into shore power I get a constant buzzing noise. For the next few months I’ll be full timing in the rig and I would like to fix this before I lose power all together and to get rid of the buzzing. I am hearing so many different things though. Some say transfer switch, some say relay, some say normal, some say it’s a sure sign of going bad. I just want to replace it or whatever is bad and be done with it but I have no idea what I need. Can anyone help? Thanks!

rgatijnet1

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Posted: 02/13/18 11:23am Link  |  Quote  |  Print  |  Notify Moderator

It could be many things from low voltage to dirty contacts to a loose wire. If you are not comfortable working with the transfer switch find someone who is.
Basically you take the cover off, clean all of the contacts, and check to make sure all of the wire connections are tight.

dougrainer

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Posted: 02/13/18 12:08pm Link  |  Quote  |  Print  |  Notify Moderator

Does the transfer switch at different plug ins? Or, are you just hearing the noise where you have it plugged in right now. Voltage and Frequency will have an affect on older transfer boxes and make them hum/buzz. You need to verify that you 120 power is within spec(110 to 128) and the frequency is correct. Are you using any adapter from the shore cord? Doug

pianotuna

Regina, SK, Canada

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Posted: 02/13/18 02:13pm Link  |  Quote  |  Print  |  Notify Moderator

Call Randy at Best Converter. Get a new power center with a more modern converter.

The buzz in mine was a relay to prevent the (lousy) converter from frying the starter battery.


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MrWizard

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Posted: 02/13/18 05:19pm Link  |  Quote  |  Print  |  Notify Moderator

the transfer switch IS a 'relay'

on a 30 amp RV the shore power is normally the selected line and the switch should not be buzzing

the generator is on the open side that closes and makes switch/relay contact after the generator starts

if you don't know anything about electrical
get an RV tech or friend who does, to look at it


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garyemunson

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Posted: 02/13/18 06:39pm Link  |  Quote  |  Print  |  Notify Moderator

Transfer switches buzz because the two metal armatures are not 'sealing up' tight together. Dirt will find it's way in and AC relays do not like anything between the two surfaces. If an AC relay does not 'seal up', it's coil will draw extra current and a buzzing relay will be much more likely to burn up. If you feel capable, you can take the relay apart and clean the two laminated surfaces. Putting a piece of fine sandpaper on a flat surface and rubbing each armature across it to clean and flatten the surface will help. When the surfaces get really beat up, you'll need a new relay. Just something else that will last much longer if you maintain it by keeping it clean. If it isn't buzzing, it's not getting damaged.

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Posted: 02/14/18 07:50am Link  |  Quote  |  Print  |  Notify Moderator

I used to have a buzz occasionally that I thought was the ATS, turned out it was the converter nearby. There was a set of old batteries I was hanging onto trying to squeeze as much use out of them that I could and when they were inadvertently depleted like during a long road trip with some dry camping, when I'd plug into shore power, the converter would buzz because of the heavy draw caused by those batteries as they charged up. Once they approached full charge, the buzz would fade.

So check to be sure it's your ATS buzzing and not your converter.


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BigRabbitMan

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Posted: 02/14/18 10:47am Link  |  Quote  |  Print  |  Notify Moderator

My transfer switch default is to the generator so when plugged into shore power there is a buzzing sound as it holds the contact closed to keep the shore power connected. It has been that way for 17 years and the coach is always plugged in when i am not on the road. I expect that it is normal for the age of your coach. Mine is a '76 model with the original transfer switch.


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garry1p

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Posted: 02/14/18 11:50am Link  |  Quote  |  Print  |  Notify Moderator

Many transfer switches have a 110VDC relay coil if the DC has a ripple from a bad capacitor or rectifier diode you can get an ac hum.


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MrWizard

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Posted: 02/14/18 12:27pm Link  |  Quote  |  Print  |  Notify Moderator

is the hum coming from over the fridge

or under the floor/kitchen area

my converter is in the outside storage bay, under the kitchen sink

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