12v Stereo "hum" from 110v converter

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kjb8000

Member
Joined
Apr 10, 2010
Posts
5
I wired in a 12v car deck. When the 110v power is plugged in, I get a noticable "hum". The noise will stop when I unplug the 110. Has anyone had this problem?
I'm aware that there is an automotive filter to eliminate spark plug noise. Does that work or is there another soloution to this?
 
Try a filter for alternator noise, or add a electrolytic capacitor of several thousand micro farads across the output and if neither help than may have to get a new converter if that does not work.
 
Do you have a Magnetek 6300 series converter?  If so, there are two outputs.  The main output is unfiltered and will create the hum you're hearing.  But there's also a battery charging output that is filtered and won't hum.

Look at your fuse board - you should see the fuses spaced in two groups.  The filtered outputs are to the right and will probably include the TV outlet.
 
By the way the best thing to do with a 6300.... UPGRADE.  At one time this was a very good converter.. But today there are much better ones out there

http://www.bestconverter.com sells upgrades.. And you can use info from their site (Scroll down to "Extra Info" frame) to walk into any RV store and pick an upgrade if you would rather shop brick and mortar type stores.
 
If the Batery is hooked up t shouldn't hum the batery acts as a filter. If youwant to ptop hum get a filter from Radio shack.
 
tvman44 said:
Try a filter for alternator noise, or add a electrolytic capacitor of several thousand micro farads across the output and if neither help than may have to get a new converter if that does not work.

+1

A 4700uF, 35v capacitor between power and ground will solve your problem.  Get it as close to the stereo as possible, and be sure you get the + and - right or it will blow up and make a big mess.

 
IF the original poster has a Magnetek 6300, or another unfiltered converter (likely because of the hum), you can't just add a large capacitor to filter the output. 

The converter is putting out half a sine wave with a RMS value of 13 volts.  Add a large capacitor to this and it will charge to close to the peak value of the unfiltered waveform, raising the DC output to that level.  16-18 volts is way too high for most 12 volt loads.
 
Really?  They don't have series chokes or anything?  The battery would do the same thing, if it's just unfiltered, unregulated chop.
 
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