Monday, August 25, 2014

Begin console printer (typewriter) mechanism and card reader restorations - Monday Aug 25

My first task when I began work in the late afternoon was to reform the electrolytic capacitors in the card reader power supply. To do this, I disconnected all the power wiring from the PS to the rest of the machine by removing all the wires on terminal block 2, then temporarily wired the PS for 115VAC input. This allowed me to hook up a Variac to slowly bring up the voltage.

Terminal Block 2 - outputs of the 1442 power supply
I started the Variac at 20% power and took my first measurement on the +12VDC output terminals. It was already at 12V! I dialed the Variac down to zero and thought for a second. The PS in this unit uses a ferroresonant transformer, similar to the one used in the 1131 for some of the supply voltages. This kind of transformer is designed to saturate its core even when voltage is low, with the result that any voltage above that point produces no change in the output voltage. It is a form of voltage regulation. In this case, less than 20V input to the transformer takes it to full saturation.

That means my plan to gradually increase the voltage was foiled, as I gave the capacitors the full 12V supply right at the outset. Fortunately, there was no immediate failure. I brought the Variac back online but monitored the 12V output to pick a point where the capacitor had only about 4-5V across it - about 10% on the Variac yielded this - and then inched it up in stages.

Once I had full line voltage on the PS and it was holding up well, it was time to wire it for its permanent input of 230V. I put all the PS output wires back onto the terminal block and closed up the PS enclosure. IBM's usage meter has its own power supply which had to be altered to change from 208V to 230VAC mains. There was a comment about the main motor wiring, but it referred me to the diagram on the access plate on the motor. When I opened it, the only choices were low voltage (115) or high voltage (208 or 230), nothing required to distinguish 230 from 208.

I opened the logic card compartment, removing the crumbling and gooey foam inside. I cleaned it off in preparation for installing some neoprene on the cover. There is an air filter which was clogged and filthy - I initially vacuumed the dirt off it but will be replacing it soon.

The three external card reader covers had the dreaded foam too - I had removed a lot of that foam before transportation but still had the tarry residue on the inside of each cover.

Foam from top cover fallen into mechanism
Foam from another upper cover

Remnants of the fallen foam
I tried various means of removing the last of the foam and its glue - nothing was perfect but after about an hour I got the inside of one reader cover clean enough to install new sound deadening. Two more to go, then when the new neoprene supplies arrive tomorrow I can start installing it.

Fiberglass encased in cloth 'jacket' - no crumbling here

Felt sound deadener - also no crumbling
The upper mechanisms of the reader/punch are filled with the gritty powder left from the crumbling foam. I will need a soft brush to loosen it while I hold the vacuum cleaner nearby. It has really covered everything, and has to go before I can lubricate and adjust the mechanical stuff.
Powdered foam everywhere

Getting into everything

more foam residue
Delightful gunk bonding with oil and grease

Like having sandpaper in the transmission

I also began the task of loosening the congealed grease and oil in the console printer. When I began, the typewriter mechanism wouldn't rotate at all, it was so gummed up. I applied a good penetrating oil (Marvel Mystery Oil) at every point where oil and grease was used, which will gradually loosen and flush away the crud inside.

Inside of the console printer (1053 typewriter) during relubricating
I have a great tool for fixing selectrics - a hand-crank that screws into the main rotating mechanism, allowing me to turn it myself. It is good for moving to a specific degree of rotation for typewriter adjustments as well as rotating fully to check out the operation of the typewriter. When I began, the hand crank couldn't turn the mechanism, but by gentle rocking I worked the penetrating oil into the gummed parts and loosened them up.

Hand crank installed into operational shaft (power section)
Soon, the operational shaft was rotating, although still with a bit too much drag, continually performing an index operation (line feed). The gumming was keeping the actuator for the index operation from restoring itself at the end of a line feed, so it kept doing them. This kind of behavior is quite normal for the first stages of restoring a selectric, at least until all the old lube is flushed out.

I touched the escapement bar - the piece that rotates for a space operation allowing the carrier to move right one position. However, it kept moving right, which shows that the escapement pawl didn't snap back into the teeth on the escapement rack. Grease again. I need to patiently work the penetrating oil in and move all the mechanisms until it properly handles spacing, backspacing, tab, line feed and carrier return.

Once the operational shaft functions are working (and stop when they are not selected), it is time to work on the print section. This part has a clutch that is only engaged when a character will be typed or the ball is to be shifted between upper and lower case sides. Quite a lot has to move smoothly and restore for all this to work, so that will be another long stage of penetrating oil, hand cycling and encouraging parts to move.

One final issue I found, which I have observed on just about every real 1130 I have encountered in modern times. The type ball is 'frozen' on the mechanism. The lift bar on the cap of the typeball does not release the ball. The ball is firmly planted in place. Many of the balls had the lift bar on the cap broken because a user tried to remove the ball.

Typeball stuck in place, cap broken off
I encouraged the two spring sections to move out from the groove in the typeball mount, but the ball was still firmly stuck. I am trying penetrating oil and gentle persuasion. It may take a while to get this to come off, but that is essential in order to be able to switch between the normal 1130 typeball (number 969) and the APL typeball (number 988).

I picked up some air filters from a home supply store to rebuild my 1131 air filters. I removed the cardboard frame on the filter, which is 1" think in its normal configuration, cut it to shape and flattened it a bit to fit inside the 7/16" height of the FF-5 filter frames in the machine. The new filters look much better than the foam I was using before. I have installed new filters for A and B gates of the 1131, but still have to fix the Midpack Power Supply filter and fashion a complete filter for the D (core) gate - to be done later this week.

Air filter before surgery
Trimmed section from the filter
Material being fitted into FF5 filter frame of the 1131
A finished filter ready for insertion under logic gates

1 comment:

  1. I bow in respect to your willingness to work on a selectric! When I was a hardware CE that was one piece of gear I never dared to touch - scared stiff of it! Re the reader/punch, and the speed at which the parts of the card path have to work, I bet you will need to at least partly disassemble it to make sure it's clean and all the bearings are free and the rubber rollers still flex.