Mastech power supply fuse blows intermittently

[Vytautas]

Hi, guys.

Could someone help me with my Mastech power supply problem? I got a power supply Mastech 3005-2, similar to this:

Mine has only one difference, - it does not have a separate constant 5V/3A output.
The schematic that I found is this:
http://img-fotki.yandex.ru/get/5701/dinamicvolt.61/0_48280_bd1a55c7_orig

The power supply works OK. I have an oscilloscope and have tested the outputs - there is no overshoot or undershoot upon powering on. But occasionally the fuse (4A) blows when powering on. What could be the problem? Is it an inherent design fault or something else? Could I fix/improve it somehow? Thank you.

[SeanB]

If it is the mains fuse replace with a slow blow 3.15A one, which should cure this. Most likely it is the surge current at switch on doing this.