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Dummy Load for DEC PDP computer Power Supplies


Dummy Load for DEC PDP computer Power Supplies

A while ago I made this dummy load for testing the H777 power supplies in my PDP 11/04 and 11/34.

And I have three other PDPs that have power supplies that need to be tested. But I was too lazy to allow for them when I made the unit above. So now I've made a more versatile version.

The front, showing barrier strips where the dummy load resistors connect to the top row of screws. A cable customized for each type of power supply (the one shown is for the H777) will connect to the appropriate screw terminals on the bottom row.

First power supply to be tested is the H740 in the foreground (for PDP 8/f and 11/05).  Behind that is the PDP 8/A power supply.

Rear view showing the banana jacks for monitoring the supply voltages under load.

The resistor banks that go into the two oil-filled cylinders.

The wiring to the barrier strips.

Schematic and wiring diagram.



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