Resurrecting a PDP-12 in Duluth

The keyboard is now greased, oiled, and (hopefully) ready to go! I decided to remove all of the keys and all of the codebars (the metal strips with notches in them under the keys) to make oiling easier. Almost every point where two parts have contact (like the pivots on the ends of the codebars or the contact points where the keys hit a metal spring under the keyboard) needed a few drops of oil. A precision oiler was incredibly helpful and sped things up immensely, while minimizing the oil spilled on the table... In the last post I mentioned replacing the ESC key with the ALT MODE key from a different keyboard. I decided to keep the original ESC key after all. This decision was made because the two keys were not identical as I thought, and on each keyboard the CTRL keys had a different design as well. I assume that the ESC key would be coded the same as the ALT MODE key, but to be safe I left it as it was. In the future I may consider swapping the CTRL keys and the ESC/ALT MODE keys ...

Last night I started removing keys from the keyboard that are cracked, or that I just wanted to replace (mainly swapping the ESC key for the ALT MODE key.) I will need to get some cleaning supplies and clean down all the keys and the cover before oiling and re-assembling the unit. I also disassembled the modem to look for any more information on it, but alas, I found nothing helpful. I found some large capacitors that look suspicious. They have what appears to be hints of some corrosion on one of the terminals, but it could also be old solder or flux.  I will remove them from the circuit later to test them further and see if they are truly bad. I also found a corner of one of the boards that has some suspicious burn marks. I suspect this was from a soldering iron, but I will check the components over thoroughly just to be safe. The dark green board is probably one of the most populated PCBs I have ever seen.

I have started work on the Teletype now. The first challenge was figuring out how to take things apart. Everything is so well designed that it all fits perfectly in place with very little space between parts. I am starting with the keyboard assembly first. I will be cleaning it and then replacing keys (if needed) from our spare ASR-33 to make the nicest looking keyboard I can. Removing the keyboard was a challenge as I had to run to Sears to pick up a slightly longer and thinner screwdriver to get at the mounting screws that were a little out of reach.  I removed the modem that was attached to the Teletype in order to get at the keyboard better. It appears that all communication to the computer and Teletype goes through the modem first. I have yet to find any schematics or documentation for it (If you know of where it might be hiding, please don't hesitate to let me know!) There will be more posts soon as I start oiling and greasing the countless gears...