HELP! HAL is in my IBM!!
October 24, 2014 2:45 PM   Subscribe

I just picked up an IBM electric typewriter from a salvage shop. However, as you can see HERE, there's something a little bit strange going on. Any electricians out there who can give me some insight? Thanks!
posted by crazylegs to Technology (6 answers total) 1 user marked this as a favorite
I'm not an electrician... but what you have is a good old fashioned short circuit. The circuits are closing for all (or most of) the keys at once.
posted by sonic meat machine at 2:54 PM on October 24, 2014

Looks like the same arms are firing over and over again.

Pressing a given key initiates a cycle, the last step of which is supposed to restore the key mechanism to the latched state it was in before the key was pressed, and it appears to me that this last step is failing, and so the type arm just flails away.

It might simply be that the thing that restores the latch of the key is not strong enough to restore a bunch of keys all at the same time -- which were pressed when it was turned off, say -- but that would be a pretty strange design vulnerability, I'd think, unless there is a mechanical interlock which is supposed to prevent more than one key from being successfully pressed at a time that has also failed.

Maybe the thing to do might be to unplug it, get the covers off, and turn the mechanism by hand (via a belt which is turned by the motor?) and see what accomplishes this last relatch step and relatch all the keys that are tripped by hand, then turn it back on and see where you are.
posted by jamjam at 3:30 PM on October 24, 2014

Not an electrician and no insight to offer, but the timing on that couldn't be better. Put the typewriter out next week and warn trick-or-treating kids about the ghost who will go berserk if they touch that key - you'll have the most popular house on the block! You can build up a whole gruesome backstory to tell older kids...
posted by current resident at 3:52 PM on October 24, 2014 [6 favorites]

Maybe you could check the switch insulation 1000494 on your IBM Electric Model A? Any way, here's a manual. Good luck, make us proud.

aaa sss ddd fff hhh jjj kkk lll
posted by Rob Rockets at 4:09 PM on October 24, 2014

This is not an electrical problem. It's mechanical. You need a technician, not an electrician.

That looks like a Model B. It's been a looooong time since I worked on one of those, but my first instinct would be to tip it back and look at the underside. There is a rubber coated roller (called a power roll; you can see it in the picture) that "powers" the keys. Try cleaning the roller with a degreaser (we used triclorethane, don't know where you'd get it). Rubbing alcohol might do the trick.

But that's not your only problem. The keys are getting tripped and not resetting. While you're looking at the underside you may spot the problem. I'll browse the manual that was posted and see if it jogs my memory.

(former IBM typewriter tech)
posted by caryatid at 5:13 PM on October 24, 2014 [8 favorites]

I'm sorry, Dave. I'm afraid I can't do that.
posted by Cranberry at 11:49 PM on October 24, 2014 [3 favorites]

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