DEC PDP-9 Restoration

12/22/12

We removed the 709 power supply and checked for physical damage. Everything looked OK.

We reformed all of the capacitors in the power supply because it had not been powered on in a long time.

This is a process were a power supply is voltage limited to a little less than the rated voltage of the capacitors

and is current limited to about 20mA is connected to the capacitors. The voltage on the capacitors will build to

the set voltage over several minutes. Once this is completed the oxide insulating layer is rebuilt in the capacitors

and the will work OK. If you just turn on the power supply you will likely damage the capacitors.

We also reformed the electrolytic capacitors on the boards in the core memory system.