Check that you are getting the correct amount of incoming AC voltage. It should fall between 103 and 130 volts AC. High or low voltage can damage the converter and other electrical appliances. Next, check the polarity and make sure it is correct. Be sure to see that the battery isn't the problem and is working properly. All the electrical connections must be clean, dry and tight. Analyze the systems closely. Systematically consider the whole DC system in general.
Consider the problem area from all angles. Look at the components in order. Then accurately measure and record the incoming AC line voltage, the voltage in the battery through an open circuit test, and the voltage going out of the converter without the battery being connected. Next, test the converter output voltage with the battery connected. With all this information in hand, the mechanic will appreciate the help if you take the power converter in for service.
Due to the advancements in today's power converters, it is probably best to ship the converter in for repairs if there's a problem inside the converter. Some RV service centers may be able to repair problems inside the converter, but most don't have the necessary equipment. Most parts are not repairable in the field. It could be cheaper to by a new one.
