Fired up the HP 226519 50V 57Amp power supply for the first time. The connectors are Unobtainium, but I didn't want to damage them by soldering to the terminals. So I soldered to the AC inlet board for now.

• Take the cover off to expose the boards and wiring
• Remove the small AC input board with connector and filtering
• Solder 240 line cord to back of board, including green to middle
  
• Connect green wire to ground mounting hole with 6-32 screw and nut
• Tape the assembly for safety
• Sacrifice a floppy disk power connector per the k3hkr page
  

It might be possible to do this and reinstall the board.

On plugging it in, the fans run and the floppy disk switch works, the output shows 50.4V on my meter. The fans run 10-15 seconds after unplugging...fair amount of energy storage there.

The power supply consists of a AC line board and an output and control board. The power interface between them flows on three relative heavy wires. Putting the scope on those wires shows about 800V square wave at 100 kHz on each. This power apparently flows into some transformers on the output board that have the label "Hi-Pot".

The output board has "Astec" printed on it, lending some support to the idea that HP buys them from Astec. If so, the Larcan site has a manual.

I'm trying to understand the design for this supply to see if it's useful for other purposes. My thoughts so far...

• Input power factor correction generates a filtered 400V DC bus
• 100 KHz H-bridge inverter from 400VDC generates the 800V square wave
• Not clear why 3 wires at 100 kHz, 3 phase? But there's only two transformers
  
• The two stages have no line isolation, producing +/-120V AC offset
• 100 kHz feed two transformers on the output board, providing isolation (and lower voltage)

How to use this for other things...

• 5X Voltage multiplying from 800V square wave to run an 8877, GS-35B
• 400VDC at 7.5 amps for ???
• 3KW induction heater power supply