DEC wiring colors and the PDP-8/e PSU

From: Ethan Dicks <erd_6502_at_yahoo.com>
Date: Mon Oct 21 23:41:01 2002

I think I have repaired the circuit breaker in my PDP-8/e, but in
my efforts to reassemble the dismantled breaker, I am concerned that
I might have swapped the hot and return wires (black and white) from
the mains plug.

For internal AC wiring, I have seen in this power supply and others
(of the -8/i and -8/L vintage, among others) white and red wires.
Is it white-to-white, black-to-red?

The problem with my breaker turned out to be curable by tightening
up the pivot points of the double-jointed contact-throw mechanism.
The design, it seems, depends on the back-pressure of the movable
contact into the fixed. One breaker stayed extended, while the
other collapsed before the throw was complete. As there is a
linkage that trips both at once, that's all it took. I think there
was excessive side-play that meant the weaker breaker couldn't
stand the pressure at the main joint and it popped.

Before disassembling it, the symptom had been that I could reset the
breaker dozens of times in a row and never have it stick. Now, it
seems quite mechanically reliable. Haven't applied power yet, for
obvious reasons.

Thanks for any tips. If anyone happens to have their PSU dismantled
enough to see the back, I need to know which half of the breaker,
white-lead or black-lead, attaches to the lone white wire, and which
one attaches to the red wire (with a companion wire).

Thanks,

-ethan


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Received on Mon Oct 21 2002 - 23:41:01 BST

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