11/45 progress

Jay West jwest at ezwind.net
Wed Mar 14 17:11:45 CDT 2007

A darlington (Q1) and a zener (D3) later... and my +15v (as well as -15v) 
has returned to the requisite spots on the backplane.

Thanks a TON for the schematics Christian & Al, extra thanks to Al for the 
entire 11/45 printset!! Oh, and Tony, the description of the power supply 
circuit and test points was most helpfull. Thank you! I understand the 
supply itself, but I'm not sure I understand the control circuits just after 
the darlington that will shut it down.

The machine now springs to life and passes all the front panel tests I would 
normally do. I did manual store/recall of various patterns in core. "clr pc" 
in loc 0 loops as does "br ." in any location. The box also passes a trap 
catcher program. Lastly, it passes a memory address test (puts the address 
of each memory location in each memory location and then verifies).

Next I would like a way to test interrupts in this minimal configuration 
(that was where the problem was before, no matter what device interrupted it 
would always trap to the same address). I would assume I have to put 
something like an M7856 in next in order to test this. Sound like a 
reasonable next step? Remember, in the config I have right now I've just got 
3 quad SPC slots... hex cards are not an option (yet).

On another note... the power control board (5409730) was well... really 
poorly soldered. I'm not an expert solderer, but those joints looked awfull. 
Not to mention I had a difficult time getting any of the old solder to be 
absorbed by my solderwick. Is this a characteristic of old solder? My iron 
was at 750f, I'd think that'd be plenty (it is for my own new solder).

Thanks for the input folks!

Jay West 

More information about the cctalk mailing list