From: John De Armond Subject: Re: New Q about Leaving converter plugged in Date: Tue, 12 Oct 1999 03:06:46 EDT Newsgroups: rec.outdoors.rv-travel bobreg@my-deja.com wrote: > > Hi, > I also has the hum coming from the converter. I installed the > transformer on rubber bushings realizing that the louder noise was not > coming from the transformer but from the contactor. I had to remove the > converter again and to install the contactor on rubber bushings. It > reduced the noise but it did not desappear. Contactors should not ever buzz. The buzz is usually caused by crud being between the solenoid pole(s) and the moveable armature. Such crud will cause buzz. It will also make the solenoid coil draw more current which will shorten the life of the coil. Sometimes the crud is a little coil varnish on the pole piece. A close examination will usually show why it is buzzing. > > And what about the fan? The noise is a lot louder than the hum. Did you > get rid of it or does your converter/charger not have a fan? Another one of my pet peeves. I *hate* fan noise. I address it by putting the fan on a thermostat. I use a gas furnace fan thermostat. This fixed-setpoint Klixon-type thermostat typically closes at about 130 degrees and opens at about 120. While a thermostat you buy from an name brand dealer probably won't be marked with the setpont, the universal thermostats normally sold at appliance and maintenance supply warehouses usually are. Try to find one that trips as low as 110 degrees if possible. To install, find the hottest part of the unit, normally the heat sink for the transistors or diodes. Mount the thermostat to that object and connect the fan in series with it. If you cannot identify a hot spot, mount the thermostat inside the top of the case. My converter does not have a fan but my welder and my 60 amp battery charger do. The welder's fan never runs unless I'm welding continuously for a long period of time. This is good because that fan sounds like a Hoover! The battery charger's fan only runs when either fast-charging a completely dead battery or using the charger to boost start a car. A slightly more sophisticated solution is to use a variable speed muffin fan that contains a built-in temperature sensor. The fan's speed varies according to the temperature the sensor sees. The fan will normally run at a constant but slow speed. This is better than the on-off operation of a thermostat, particularly when the fan has to cycle under normal conditions. These fans are available from Ametek/Rotron (http://www.rotron.com) and Papst Mfr (http://www.ebm.com) among others. MCM Electronics and Newark Electronics are two distributors that stock these fans. John |