Abstract: The power supply includes a transformer situated in an enclosure having a movable cover. The transformer is immersed in oil and the electronic components associated therewith are affixed to a support connected to and movable with the cover. To eliminate the necessity for an independent external cover lifting mechanism, normally required to move the cover to permit access to the interior of the enclosure because of the weight thereof, a counterbalancing mechanism, situated wholly within the enclosure, is provided to facilitate servicing of the electronic components. The mechanism includes a pair of planar counterbalancing members, each of which is mounted for movement along a different interior wall of the enclosure. Each member is connected by cables to the cover, the cables cooperating with sheaves, rotatively mounted to the enclosure wall. The counterbalancing mechanism requires no additional space within the enclosure and is comprised of simple, inexpensive and reliably operating parts.