PDP-8/E PSU Debugging (was Q-bus pinout)

From: Chuck McManis <cmcmanis_at_mcmanis.com>
Date: Fri Apr 9 23:07:03 1999

Ok, much probing and spying with flashlights later ...

The back connector has had the 5v line removed from it, (the wire is tucked
inside the PSU with heat shrink tubing over its end) and instead this pin
is connected to a wire that is soldered to the _underside_ of the bottom
board below the heatsinks. (toward the front of that board but I haven't
tried pulling the board yet.)

If I had to hazard a guess, I'd say that someone had ECO'd this 8 to sense
the voltage level on the bus using the rear connector by connecting 5volts
at the back of the bus into the regulator board in the PSU.

Ring any bells for anybody?

If that's the case then perhaps I've got a problem in the bus jumpers.
Question for the gallery:
        If you are looking at a PDP-8 from the "front" which side is the "A"
connector and which side is the "D" connector? Or put another way, is the A
connector on the front panel closer to the key or farther from the key,
than the D connector?

--Chuck
Received on Fri Apr 09 1999 - 23:07:03 BST