11/45 revisited

Jay West jwest at ezwind.net
Fri Mar 9 16:27:52 CST 2007


Told ya'll I was going to dig back in to that 11/45 restoration project :)

Got the workroom cleaned up enough to actually have room to work on the 
thing. Stripped it down to the very most basic configuration possible 
(including getting rid of the 9312 for a 930, etc.). Barebones. No cards in 
SPC slots except grants. Known good 16K of core and then a base processor 
set (without segmentation and without FP).

Turned on the bottom 742, then the top one... fans all come on but nothing 
on the front panel at all. Checked the obvious front panel keylock, it 
wasn't off. Time to check voltages & ripple on the backplane.

E02B2 is at 0.55v, indicating the H745 in slot E is officially a problem 
child.
E15A1 is at 0.95v and E01B1 is at 0.05v, so the +15v regulator built into 
the top H742a is suspect. Noted that the small fan on the top of the top 
H742a isn't turning so likely the regulator is well-done.

The test points on the backplane for regulators B, C & D are ok, as is 
the -15v from the bottom H742a.

Time to get the H742a docs from bitsavers :)

Jay West







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