There can be many reasons for power to go on and off mostly because of faulty equipment or parts of equipment .
Any "ideas" you get from here based on the info you supplied will be just that - ideas.
Do you really want to spend money for parts based on that ?
Get a cheap simple multimeter and read the manual and do some investigating into what exactly is going on .
Are you loosing the park AC input or just the DC output from your converter ?
Some very sharp folks read this forum and with some facts could certainly advise you .
Good Luck, Mike