Thursday, May 28, 2015

More time dedicated to the typewriter space, tab and carrier return functioning

Yesterday was such a full day that I didn't get to the 1130 system at all. I was able to help repair a power problem on one of the 1401 systems at the Computer History Museum, during my weekly midday visit, the rest of the day was absorbed by my day job and spent the evening helping my wife, who had a dental crisis with an infected tooth, one that had an old root canal but had cracked internally and abcessed.


I did some partial dis-assembly to work on the sticky carrier return restore, the blocked space button and the failure of the tab button to reliably trigger the space/backspace/tab cam cycle. I had to remove a brace, the motor starter capacitor, unhook the main spring, and loosen the tab/rewind pullies.

With the improved accessibility and visibility, I cleared up the escapement issue that blocked the space button from advancing the carrier. It took quite a bit more to fix up the carrier return issue. I unhooked a few parts of the intermediate lever, latch and restore parts to isolate where the binding is occurring.

My work for the day improved the restore operation substantially, but not completely yet. If it was restoring about 30% before today, it is now restoring to 80% and moving much more crisply. I still need it to get to 100% promptly.

I turned my attention to the tab mechanism. The interposer isn't snapping back far enough to trip the space/backspace/tab cam cycle, although the space and backspace interposers work reliably. Something was different about this one interposer.

One difference is that the interposer has to turn on a microswitch during its trigger, which is switched back off by the end of the cycle as the clutch operates. This would add a bit more resistance, but the design should have sufficient spring tension on the interposer to handle this.

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