Thursday, November 12, 2015

1053 carrier return cord attached; working on DMS2 distribution deck recreation


Refastening the carrier return cord - the cord that pulls the carrier to the right during space and tab under pressure from the mainspring and which in turn winds the mainspring during carrier return operation - is a huge pain. There are two counter-winding pulleys on a common shaft, one taking up string during rightward movement and the other taking up string during return, with that shaft connected to the mainspring. The cord has to fit over five small pulleys in its run.

To be precise, there are two separate cords. one winds up on the pulley during rightward carrier movement, goes around two smaller pulleys and hooks to the carrier on its right side. The other cord is attached to the pulley that winds up during carrier return operations, goes over three intermediate pulleys and then hooks to the left side of the carrier. One of the small pulleys for the first cord is also spring loaded, in order to establish the right tension but buffer the cord from minor stresses during operation.

The return side cord is wound on its pulley, routed over three pulleys and the carrier pulled rightward to keep it taut. Then, the forward side cord is wound on its pulley, routed over two pulleys including the one with spring pressure, then hooked to the carrier. To get the right tension involves a gross adjustment and a fine adjustment.

The gross adjustment comes from loosening two hard to get to screws in the rear return side pulley where the return cord winds, rotating that pulley on its common axis relative to the rightward cords winding pulley. This is quite hard to do, as the two cords have to be on all their pulleys and in the right grooves of the two winding pulleys, while I hold one and try to rotate the other relative to it.

When the gross adjustment gets the cord to be free of slack when the small spring loaded pulley is partway depressed, then the fine adjustment is done on that spring loaded pulley to set it in the middle of its travel range.

I spent 30 minutes fighting everything and have the gross adjustment almost were it needs to be, but get frustrated by all the spots where cords can pop off pulleys or jump over grooves as I manipulate things.

When I took a rest break and returned, I was finally able to get it back together. The gross adjustment is decent, but I don't have quite enough tension on the spring loaded pulley. For now, it will be good enough.

The next area I need to look at carefully is the interaction between the carrier and the margin mechanisms. I have had the carrier 'jump' over the left margin during some return operations, which is definitely not acceptable, which implies either a bent part or some alignment that needs changing.


I now suspect that the file format of the tray images I found on the internet are big-endian rather than little-endian, which foils the display utilities from the simulator. Meanwhile, I continued testing and developing more of the code that will create the object decks for a System Load of DMS2.

The code that reads a system file into a buffer, given the SLET entry for the file, is working properly. The next bit of code is the subroutine which will punch that buffer as card images in the proper format for use during the system loader process, putting out the right header and trailer cards as well. When debugged, it can be combined in a mainline routine that reads in the SLET and walks through the entries to punch out the decks for them.

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