Wednesday, March 18, 2015

Looking at options to repair feed wheel of 1442 reader, while continuing SAC Interface construction

I am out of the house attending a conference this week, plus some other obligations while home, that will limit how much I get done until the end of the week.


The feed wheel 'tire' which sustained damage during dis-assembly will be a challenge to repair or replace, but essential if I want this unit to be able to punch cards. This component has a pair of wheels on a common axle, the wheels have some kind of ceramic 'tire' around the rim with a gritty surface to grab card stock well when the pivoting metal roller is squeezing the card onto the feed wheel from the other face of the card.

The diameter is important in determining the distance between columns during punching, while the degree of grip must be consistent between the two wheels to avoid any skew in the card motion as it moves from column 1 down to column 80 during punching. I am afraid I may need to symmetrically replace the tire on both wheels to ensure the consistency, but that is not certain yet.

The undamaged feed wheel

Ceramic like material split at the point where it had the grit added to the binder

Edge on view

Another view of the damaged 'tire'
Mark Sims has offered some advice on possible repair methods, all of which are being considered.


Working with an entirely new FPGA board with different firmware for the USB chip, a new toolchain for that USB device, changed pin assignments and a different way of communicating from the fpga require quite a bit of time to study, design and implement the system and begin testing.

Toolchain I will use - there are also web server and java interfaces

I got the VHDL for the board to the point where it would push the state of the signals coming in from the 1131 out to the PC and it set the outgoing signals to their default idle values. This will let me power up and verify some very basic functionality. Now fighting the new tools to get this all synthesized, turned into a bit stream, pushed onto the EEPROM on the board and to get the USB processor firmware I wrote downloaded.

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