PDP-8/E questions - test-drb@ccmp.vtda.org

24 Nov 2001

On Nov 25,  1:28, Tony Duell wrote:

...
   What's J5
(3-pin Mate-N-Lok) on the PSU for? 
 AC output (centre-tapped) to the line time clock board or power-fail
 interrupt board. Watch out, it comes straight from a secondary on the
 mains transformer. There is a fuse, but it's in series with the centre
 tap only. Which means that shorting the outside 2 pins together can burn
 out the transformer. 
Ah.  That would probably explain why I have a cable with two white wires on
pins 1 and 3, and a red wire on pin 2, connected to a 6-pin single-row
Mate-N-Lok (like the ones used on power regulators).

...
   And lastly
(for now :-)), which direction should the fans blow? 
 I am not sure what the offical way is, but if you reverse the fanse
 aren't you going to be blowing hot air (heated by the PSU) over the logic
 cards? Most machines I've got where the fans are between the logic and
 the PSU draw air in over the logic and blow it out over the PSU heatsinks.

It doesn't get very warm, but then there's not much in the machine at the
moment.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York