Check the battery to make sure it is good. Sometimes this is the most simple, but often overseen, problem.
Check to see that the incoming current to the converter is from 103 to 130 volts AC. If it is at any other level, it could ruin the converter or anything else it is running through.
Look on the converter to make sure the polarity isn't reversed. If it is, you need to adjust it.
Look to see whether all the connections are dry, cleaned and tightened.
Analyze the system closely. Carefully consider it from every different angle.
