Hewlett-Packard 711A Tube Power Supply Restoration

In the vacuum tube era, an engineer’s bench would often include a power supply able to provide the hefty voltages those devices required. The Hewlett-Packard 711A [PDF], introduced in 1954, was a particularly robust and versatile example, sourcing up to 500 volts at 100 milliamperes with output protection and excellent regulation. This unit, built in 1960, is in pretty good shape for its age, but needs some work to be rejuvenated to power vintage tube circuits in the 21st century.