13 Oct
2006
13 Oct
'06
5:41 p.m.
It's not
quite as bad... What you do is :
Remove top cover, loosen the top screw holding the PSU ('backend of the
chassis) on each side, and remove the bottmo 2 screws on each side. Then
swing the CPU to the vertical position (That's one reason why the rack
slides have a tilt mechanism) and the PSU will swing away from the
backplane are. Unplug the 8 pin mate-n-lock, remove the 3 screws and
slide the regulator out.
The connecotrs are on the front of the regulators themselves, not the
connectors on the power distrbution PCB
Yup, for all their supposed 'engineering prowess' DEC did some mighty stupid
things sometimes, especially in the 1970s vintage systems.
Of course the above process only works well if you happen to have a
BA11-K box
rack mounted with those cute DEC tilt slides. If not, then you are in for
If your BA11-K is not in a rack, then loosen/take out the screws as
above, then tip the CPU box onto one side. You can then ease the PSU away
from the rest of the CPU and get the regulator out.
a major overhaul. And by the way try and do all this
without bending a
backplane pin...
Think the 11/34 in the BA11-K box is bad ... just try and get to the power
supply to replace the fan in a PDP-8m. You have to take the whole box apart.
I am sure I've stated ARD's law of DECSA construction before -- 'The
lower the importance of a part of a DECSA, the more screws hold it in
place'. The PSUs are held in my 2 screws, the fan tray by 4 screws, but
the grille over the fan tray is held on by an amazing 28 screws.
Removing the backplane from a DECSA is an entertainment. Everything else
has to come out first...
-tony