PDP-8/M Rebuild – part 1 – Initial Inspection

I’ve finally decided to bite the bullet and start the rebuilt of one of my OMNIBUS PDP-8s. I decided to start with the more challenging of the two using the theory that by tackling the worst I would be much better prepared for a simple rebuild of better condition machine.

An appraisel of the machine

Before commencing, I will carry out a thorough appraisel of the machine so we can get a measure of the job in hand:

Front View

The front panel is in reasonably good shape. The plexi is mostly unmarked and the surround isn’t too grimey or scuffed.

A few of the console switches have broken but most are repairable and I’ve been kindly given a few spares which will make up for the missing ones.

The Backplane

Inside, the box is mostly clean, a few rust blisters but nothing too worrying. The backplane looks in good shape.

The power supply has already been moved and I will detail this later in the post.

The build label

The build label reveals that the machine was once fitted with:

KK8E Processor
KL8E Serial Console
3 x MM8E core sets (giving 12KW of memory)

When the machine arrived it had no cards. I’ve since aquirred a KK8E, KL8E and RX8E. For memory I plan to use one of the MM8E sets from my other 8/M

Power Supply

The power supply arrived loose in the box. It isn’t too bad, although has received some somewhat rough patches during its life. One area of concern is the two missing power transistors at the front of the supply.

I plan to rebuild the machine in the following stages: