Power problem with Behringer eurodesk audio mixing desk

[jmackenzie]

I have a Behringer SL3242fx-Pro mixing desk , which has recently developed a strange fault. About 5 mins after switching it on, the power starts to cycle off and on every few seconds, with resulting pops in the audio output. If I switch on the phantom power section of the desk the frequency of the cycling off and on increases.
Has anyone ever seen this type of thing with power supplies? (I am guessing that it is a power supply problem.) I have disconnected all audio outputs and inputs .
This mixer does not have a power amp built in.
Any ideas would be welcome as I am unable to find a service centre nearby.