Sunday, March 15, 2015

Tearing down the punch unit of the 1442, wrapped up construction of the SAC Interface box, on to programming and debugging


I oiled the pivots and greased the cams that activate the pulleys involved in reading and moving the card to the pre-punch position. I then began disassembling the punch eject assembly, because the roller pivot was quite wobbly which has to be diminishing the force of the ejection into the cornering station.

Removing the pivot was quite a bit more challenging than I thought, because the Screw won't releease the rubber wheel, forcing me to partially disassemble the bearing, shaft through the frame and gear/belt on the other side.

I still have too much drag at the cornering station. I just don't understand it - I am polishing the metal constantly and the plastic cover too. I will play with the 'bite' of the rollers that suck the card away into the stacker stations.

I am also studying to see what kind of effort is involved in stripping the punch down and rebuilding it. So far, I have removed the Incremental Drive, the restore assembly, the magnet unit and some access plates, but still looking into how far I can safely tear it down.

I can see that the punch and interposer mechanisms work well, which is nice to know. There is still the sticky pivot for the feed wheel roller, which seems to require even more disassembly.

Near the end of the day, disaster struck. Somehow I managed to shatter some of the ceramic 'tire' on one of the feed wheels. These have a gritty ceramic applied to them, reminiscent of a grinding wheel surface, which grips the blank card stock and moves it forcefully to each of the eighty card columns during a punch cycle. With part of the circumference shattered off the wheel, I will now need to find some way of repairing this. This is not good.


This morning I installed the two 50 pin IDC connectors and converted them from female to male. I had some header strips for Arduinos which have pins that are shorter on the side that fits into the Arduino and longer for mating with other connectors, but I wanted them symmetric, the same height on each side of the narrow plastic separator strip. I used pliers to carefully modify these and tested the fit between the IDC connectors and the FPGA board. It works well.

Ribbon cables with IDC connectors to fit on the Ztex fpga board
The broken ground line on board two was resolved by tacking a wire to one of the large pads for a ground via elsewhere on the board. I also installed a wire to pull the Meter In signal to permanently off, since this is only of interest when you want to bill by the CPU usage meter and care that a peripheral may continue operating a few seconds longer than the processor - squeezing every last second of billing.

I finalized all the wiring and mountings for the circuit cards, cleared up some 160 pin receptacle issues with socket pins that were too far back in the housing, then installed the SAC cable to the 1131. At this point, I need to configure the FGPA so that it asserts the proper state on all the command lines - such as interrupt requests - to make it neutral to the operation unless my logic changes things intentionally.

The Cypress FX2 USB module requires definition and compilation of the firmware to run the USB module. This module has an 8051 microcontroller inside as well as a fair amount of direct hardware to maintain quad buffered FIFO queues to support full bore 480Mb/second operation to the PC host.

I installed the toolchain and configured the USB firmware into the board, at which point it would also allow me to configure my logic definitions into the Spartan 6 FPGA via storing them in EEPROM on the board.

I had quite a bit of remapping to do, switching the signal assignments from the old Digilent FPGA board to the new Ztex board, as well as swapping out the USB link logic.


I received my ground fault circuit interrupter breaker for the 240/120 20A link to the outdoor weatherproof socket. I can now plug in and test my interior wiring, once I stick in the breaker. Since it is dark out now, I would prefer to swap the breaker in the panel during daylight. Less chance of shorting something or worse. 

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