Verification of 1053 Console Printer controller electronics - part 2

DIAGNOSING ISSUE WITH THE LACK OF A SHIFT CYCLE DURING PRINT

I put the four channel scope on the machine and started looking at signals from the controller logic to understand why the 1053 is not shifting to the correct side of the typeball before printing. I started with the two long timers that are used to divide the approximately 50 milliseconds of a print cycle into two halves. They looked perfect.

Next I began working back to see what should be occurring such that the logic would enter a shift cycle and drive either the -upshift or -downshift solenoid as appropriate. I didn't have much time left but did collect a lot of traces to figure out the issue. 

I should see -Twr Shift Cycle go active and trigger a new firing of the two long timers which would cover the print cycle once the shift was complete. However, when I looked the -Twr Shift Cycle was only active for about 100 ns, far too short. 

My next session will start with studying all the signals that set or change the Shift Status, compare it to the B register bit 6 which is the requested case, and should produce -Twr Shift Cycle.