The 3350 Power Supply is a switch Mode Power Supply. Because of the nature and technology of a switch Mode Power Supply, certain precautions are to be taken:

1.    Do not power on without load, as the PSU needs load to function, correctly.

2.    Do not power OFF/ON in quick successions, this is because the reservoir capacitors decay in the
       PSU over a period of time, whilst the PSU is in use. These capacitors are only used when the PSU
       is powered on.

3.    When installing a PSU replacement, leave to acclimatise before power on.