Monday, March 23, 2015

Partially reassembled 1442 punch, debugging on SAC interface and some datacenter progress


I began reassembling the punch unit of the 1142 card reader/punch, up until the point where I would need the feed wheel repaired. This work put the punch restore comb, springs and lubrication covers back onto the assembly, but I can't put the incremental drive back without the wheel, nor the punch chad chute that funnels the bits of cardboard down from the punch unit to the bucket at the base of the enclosure since the chute is in the way when installing the feed wheels.


After I cleaned up the logic for the link it became apparent that the signals are not getting through to the fpga board. Time to dig into this since it now appears I am sending the signals as received, they just aren't received. Scope and logic analyzer time.

The fpga board is unplugged so I can diagnose directly from the board. With the 1131 powered down I began verifying the signal level and integrity of all the inputs on the top board of the PCB stack. Right away I found differences between circuits that should all be in the same default condition with no power at the processor. Disappointing but perhaps there is a benign explanation.


My reflective umbrella arrived and I did a quick but blinding test using it. It does indeed spread the light down, although if you look up it is still about as annoying as a direct peek even in daylight. I realize that I have to install the reflective umbrella in between roof trusses and that means the light itself has to be held by a couple of wooden sticks spanning the two trusses. That would center the light unit underneath the center of the umbrella for maximum relection and minimized blinding of occupants. 

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