Reassembly of the 1132 printer - part 4

INSTALLING RESTORE LEVERS

The Print Clutch Restore Levers were installed as they will push the Print Clutch Latch Levers so that the Print Clutch Dog is held by the end of the latch lever. They are a more complex set of bars that bolt on midway on the frame at the front side. 

The high point of a lobe on the Print Cam pushes the restore lever, which pushes the Print Clutch Latch up out of a notch on the Knockoff Armature Lever and allows the lever to pivot so the latch will sit on the high part of the Knockoff Armature Lever. 

I was able to install the assembly but the Print Clutch Cams won't rotate past the restore levers. These bars have adjustments to be certain that they lift the Print Clutch Latch out of the Knockoff Armature Lever notch sufficiently but without the restore lever bottoming out on the guide bar onto which they pivot. 

Restore lever assembly outlined in yellow

I will have to loosen this and tweak its position until I can hand rotate the mechanism again. 

REMAINING PARTS TO INSTALL

The carriage must be installed back on the printer, now that it is restored. 

When that is in place, I can drop the Print Wheel assembly into place.

The magnet assembly goes on the front of the print mechanism frame after that. When it is installed, the plate with the 120 magnets gets dropped on and that completes the main part of the printer reinstallation. 

Restoration of the 1132 printer carriage mechanism - part 2

DETENTS WORKING WELL

As the clutch solenoid plate is pulled (as if the magnets were energized), the slow or high speed clutch activates and turns the platen. The detent pops in so that it stops crisply at the nearest print line position. The CB switch plunger pops in and out correctly. No work needed on these functions. 

PLATEN DISENGAGE/ENGAGE LEVER WORKING

The front lever that engages or disengages the platen from the gears was frozen solidly in one position. I got into the mechanism, oiled it and now the lever does what it should. The operator can disengage the platen, push the Carr Restore button to skip until channel 1 on the carriage control tape has a hole, with the paper manually lined up for the first line of printing. Re-engaging the platen synchronizes the physical paper forms with the carriage control tape. 

When I put the front plate and knob back on the lever, it was frozen again. A part had been broken because the knob itself was cemented in place so firmly that someone had snapped a bit of metal trying to turn it. I will need to think up a fix for the broken part in order to have the knob, now freed up with clock oil, work as it should. 

WORKING ON CB SWITCH CONTACTS

The goal of all my contact burnishing was to get the resistance of the switch down to a reasonable level. It was sitting around 220 ohms but when it touched the ohmmeter to the two sides of the contacts, it was much lower.

I realized that the resistance was elsewhere. Push in pins connect wires to the two sides of the switch and one was corroded enough to add the resistance. I removed the pin, cleaned it up and reinserted it. Resistance now about 6 ohms. 

REMOVED OXIDATION ON INTERPOSER SWITCH CONTACTS

There is another set of contacts in the carriage, which turn on when the interposer magnet has fully attracted its arm. The interposer magnet is used to switch the clutch that will be activated when the clutch magnet is energized, switching from low to high speed operation. The switching mechanism needs to have fully engaged before the clutch magnet operates, thus the interposer switch sends feedback to the printer control logic in the IBM 1130 when the switching is complete. 

I burnished for a couple of minutes and had a great low resistance connection when the interposer mechanism had fully pulled back (as it would when the interposer magnet is switched on). 

WORKED TO LOOSEN UP GEAR TRAIN

This was the big problem in the carriage. I kept at it, flowing the clock oil everywhere I could reach and turning it by hand. Suddenly, I felt whatever glue like material was inside give way. The gear starting turning very easily. 

MOTOR TESTED WITH BENCH POWER, CARRIAGE MECHANISM IS WORKING OKAY

I hooked up the 48VDC from a bench power supply to the carriage motor and turned it on. The motor spun right up and turned the continually operating parts of the gear train. When I manually pulled the clutch magnet armature, the carriage advanced a line with the detent falling into place. After I held the interposer magnet mechanism to the switched state and then manually pulled the clutch magnet, the platen turned faster and without detents. 

PREPARING TO REINSTALL THE CARRIAGE IN THE PRINTER

The carriage is fully functional other than the broken part that disengages the platen when the front knob is turned. I can repair that with the carriage mounted on the machine. I put on all the covers and got the carriage ready to move over to the printer for installation. 

Reassembly of the 1132 printer - part 3

INSTALLING DETENT LEVERS

The Print Clutch Detent Levers rest in the notches on the cams to keep them from rotating from this rest position. While the Print Clutch Latch is holding the Print Clutch Dog so the tooth is out of the Print Clutch Shaft flutes, the cams should be sitting with a notch on their perimeter in position for the Print Clutch Detent to fall into the notch and keep the cam from turning.

The bar holding them attaches down high on the frame on the front side of the printer. The bar is a very tight machined fit between the frames, requiring quite a bit of finessing to slid the bar between the frame sides and move it up to the mounting position. I had to tap the bar with a hammer to move it around to line up the threaded holes that bolts will screw into. 

The Print Clutch Restore levers are next up. These are even more difficult to start between the frame sides, as the surface rust on the frame sides meaningfully tightens the clearance between the restore assembly and the frames. I ran out of time fighting with this by the end of the workday. 

Restore lever assembly

Space into which it is installed - about 65% up vertically in the picture

Restoration of the 1132 printer carriage mechanism - part 1

LOOSENING UP THE SHAFTS AND BEARINGS OF THE GEARBOXES

The carriage motor runs continuously as does the main printer motor. A worm gear on the end of the motor turns parts of the gearbox, so they are always turning as long as the motor switch is on. 

Continually turning parts marked in green

The left and right side gears marked in green across the center of the picture above turn at different speeds. A clutch mechanism attached to each gear can couple its motion to the center gears. When either clutch is activated, the platen begins turning at the speed dictated by the left or right gear. The right gear turns the platen at about 150 RPM while the left gear makes the platen turn at 70 RPM. 

Gears marked in yellow turn in slow speed mode

Gears marked in red turn for high speed mode

When either the yellow or red gears are turning, they also turn the platen through a driving gear and a second detent gear ensures good vertical line alignment. 

A detent gear in the gear box has notches in it at each print line position into which a spring loaded detent lever will fall. This ensures that the platen stops precisely at the next line position even if the solenoid deactivation is somewhat imprecise. 

I worried about clearing up the clutches as they are somewhat complex with plenty of spaces for lubricants to freeze up the works. 

exploded view of a clutch

I have been seeping clock oil everywhere I can reach but not getting a significant improvement in turning resistance. This is going to take some time and might require substantial disassembly. 

MOTOR TEST

The 48VDC motor wouldn't turn with the very sticky gear train connected, but once I pulled the worm gear off of the motor, it spun up nicely with my bench power supply. It is a 50W motor but when free spinning it was consuming around 32W. I tried to get some clock oil seeping into the front bearing of the motor, hoping it spins even easier in the future. 

Worm gear removed

shaft ready to spin when 48V applied

CB RESTORATION

The CB (cam driven switch) consists of a cam gear that is on the same shaft as the carriage control tape drum. It has slots for each line position of the platen.

CB microswitch

The microswitch has a spring loaded plunger on the top which rides on the cam gear. The purpose is to send a signal back to the 1130 printer controller logic every time the plunger enters a slot. The printer controller logic activates the solenoid to activate a clutch. That causes the platen to start rotating at about 70 RPM. When the plunger falls into the next slot on the cam gear, the printer controller releases the solenoid so that the platen comes to a stop.

The plunger needed to be freed up to move in and out of the slots. Once it did, I concentrated on the conductivity of the contacts. After thirty minutes of work, the resistance of the points was still above 220 ohms. The corrosion from the rodent urine soaked really deeply into the contact metal. 

Reassembly of the 1132 printer - part 2

SUCCESSFUL LAPAROSCOPIC SURGERY ON PRINT CLUTCH CAM

There was one Print Clutch Dog that had slipped off its pivot point, which I deferred repairing until this point in the assembly. I had to remove the top guide bar/comb in order to bend the adjacent disk away far enough to nudge the dog back onto its pivot. It took about ten minutes to finesse it, but mission successful. The guide bar went back on. 

I didn't have much time today as I was at the Space Force Museum most of the time. 

Reassembly of the 1132 printer - part 1

BEGAN REASSEMBLY OF PRINTER MECHANICAL PARTS

I began assembling onto the frame the subassemblies I had worked on. I first installed the Print Clutch Cam shaft onto the machine with the Print Clutch Cams all resting in their idle position. This is where they will sit if the Print Clutch Dog is held out of the shaft flutes by the Print Clutch Latch lever. 

The cams are separated by the comb slots of the guide I inserted while working on the workbench. When I put the Clutch Print Cam shaft onto the machine, there was another comb guide at the bottom into which all 120 cams had to fit. This was a very slow and tedious process, taking about an hour of time to move them carefully to fit into the comb teeth before the shaft settled down in place on the frame.

Meshed at right, trying to get the rest into bottom comb

A couple of Clutch Dogs popped off their pivots

In the process of getting the cams into the bottom comb and installing the shaft, I ended up with a few of the cams rotated compared to all the others. I also had a couple Print Clutch Dogs pop off their pivots, which I will have to resolve with a 'laparoscopic surgery'. 

I finally had the full set of cams engaged in both top and bottom combs. A third comb was added at right angles, but that was a breeze now that the top and bottom of the cam disks were properly spaced.

All engaged, with the shaft ready to attach

Third comb bar added to further stabilize the cams

I installed the two bearing caps and tightened them down. There were a number of restraining screws to reinstall that keep bearings from walking out of the side of the frame.

I then reattached the ribbon mechanisms and other parts that had been removed when I took the bearing caps apart. The left and right ribbon mechanisms are connected by a bar that runs through the print machinery, between the Print Clutch Cam shaft and the Print Wheel Drive shaft. I got that squared away. 

shaft just visible going through hole in frame

Shaft emerges at the other side

Final tweaks to the 1130 core memory replacement (MRAM) board

FINAL VALUE CAPACITORS INSTALLED IN THE TIMING CHAINS

The updated capacitor values for the timing chains arrived, but very late. They were shipped Fedex ground with a scheduled delivery of Aug 14. Due to a string of missteps and poor execution, such as sitting 36 hours in some depots before moving, it finally was out for delivery on Monday August 18th.

I did receive the package by 1PM Monday, in time to still get over to my shop for a short time. I put these new timing capacitors on the board. I then installed all 17 of the bypass capacitors at each integrated circuit location. 

BEGAN ANOTHER ROUND OF TESTING. 

As I was verifying that the replaced chips output a negative going sense pulse when a bit being read was 1, I realized I had installed 74LS03 chips which have a minimum VCC requirement of 4.75V but my board operates on 3.3V. They were working properly however I ordered 74HC03 chips which work fine with 3.3V VCC and are the same footprint. I will replace the five output chips with the new 74HC03.

I was able to verify that the MRAM chip does store data and return it properly, at least for a default storage address. I used a bench tool to generate a positive pulse for storage read and for storage write, setting up the input data and observing the sense output of the board. 

I am going to set up a bit more elaborate test where I set various storage addresses, store different data patterns in them, and then read the addresses to check that these are discrete locations giving the associated data patterns. It still uses a debounced pushbutton to emit the read and write signals. All the timing on the oscilloscope shows it should operate correctly at 1130 speed. 

CABLED UP FINAL POWER CONNECTIONS

I put together the wiring between the power regulator module and my board, along with wires that will attach to the 1130 power supply terminal strip at the bottom of the gate where the memory compartment sits. They have ring terminals on them so that I can quickly hook up the memory when I am ready to test on the IBM 1130. 

SHIELDING BOX TO BE BUILT AND INSTALLED

I do plan to build a metal box to fit over the MRAM chip since it is sensitive to magnetic fields. I set up four ground pads on the PCB where I expect the box will be soldered down. The ground plane underneath the MRAM chip is unbroken as well. 

I found a good shielding box on Amazon that would fit reasonably well - a bit larger footprint but will clear other parts on the board. It is made of Mu-Metal, a material with high magnetic permeability that would strongly attenuate any changing magnetic fields outside the box. However, once it was ordered, the vendor confessed that it is not in stock and cancelled the order. The product listing remains on Amazon with the same unrealistic delivery estimates to lure the unwary. 

I may have to form my own box, which may challenge my skills with metal work given the limited tools I own for the purpose. However, if I can form the part up so that I can solder overlapped seams and it is not too misshapen or ugly, I could use that. I bought some heavy copper sheets, since MuMetal prices were near $100 in the minimum quantities they offered. 

FINAL STEP WILL BE CONFORMAL COATING OVER THE BOARD

I will coat the board with silicone to insulate and protect it while it lies inside the gate of the IBM 1130. However, I will wait until I have completed testing and won't need to change the board or any parts on it. 

Freeing up 1132 printer components - part 8

FINISHING THE PRINT CLUTCH LATCH LEVERS

The oil worked overnight and with just a bit more work, all the levers move freely. 

FINISHING THE PRINT CLUTCH CAM AND CLUTCH DOG WORK

Most of the mechanism in the printer is lubricated by spraying IBM #6 oil on the parts without disassembly. However, the flutes of the Print Clutch Cam Shaft should be lubricated with IBM #17 grease. I have modern replacements for these lubricants. 

Thus, I began from the right side, making sure every Clutch Dog pivoted freely, that the Print Clutch Cam rotated around the shaft when the dog tooth was not engaged, and then sliding it against the finished Cam disks. I would grease up a section of the shaft and then process Print Clutch Cams until I had mostly filled that area. Below is a picture with a section of the shaft having been greased, before working on the Print Clutch Cam disks to the left of it. 

The maintenance manual recommends engaging the comb to keep the Print Clutch Cam disks in their proper spacing. It is also supposed to keep any Print Clutch Dogs from popping off their pivots. I hooked up the comb as suggested, but my initial packing of the Print Clutch Cam disks was too tight together requiring me to massage the parts to fit in the comb. During that work, two Print Clutch Dogs popped off their pivots. 

I believe I can reset the dogs onto the pivots once the shaft is back in the machine, so I will leave the two dangling for the time being. 

It is time to reassemble the printer mechanism, adjusting as I reinstall to prepare it for hand testing and eventually testing hooked to the IBM 1130. 

CLEANUP AND TESTING OF THE CARRIER ASSEMBLY

The carrier assembly has an electric motor, a gearbox, clutches, two solenoids, and the carriage control tape mechanism. First up was a cleaning - removing nut shells and other infestation consequences. I then checked the lubrication and movement of the gear box and other key parts. 

The gear train is very stiff - solidified lubricants at work - and needs much work to free up the rotating parts. 

POWERING THE CARRIER WITH A 48V BENCH SUPPLY

The carrier motor runs on 48VDC as do the solenoids that engage either single space or skipping movements. I used a bench supply and testing the motor. It attempted to turn but the high friction of the gearbox was too much for it, even with 50W delivered to the motor. I will test again once I get the mechanical parts freed up. 

CARRIAGE CIRCUIT BREAKER (CB) FROZEN AND LOOKING CORRODED

IBM uses the term Circuit Breaker (CB) for a switch that activated by moving parts - either activated by cams or in this case by a plunger popping up and down in slots around a gear. The CB will send a pulse at each line position as the carriage moves - the slots are spaced to produce six lines per inch vertically on the print forms. 

The metal leads for the switch contacts look very corroded and blackened from the acidic rodent urine atmosphere. The spring loaded plunger is frozen in position up in a gear slot. I will have to free up the plunger motion and then either clean the contacts or replace them to get this key CB working. It is how the carriage knows to stop after spacing one line. 

Freeing up 1132 printer components - part 7

PULLED CARRIER OUT OF THE PRINTER

I slid a board underneath the carrier, lifting first one side and then the other as the board slid into place. I pulled the carrier out to the left side of the printer frame, moving it across the board, then put it onto my hydraulic lift cart for transport to the bench. 

PRINT CLUTCH LATCH (TRIGGER) WORK CONTINUES

With the other parts out of the way, I have good access to all the points where the latch levers can stick. I added oil and worked them - some are still a tad stiff so I will leave the oil to seep in and finish them up tomorrow. 

REMOVED PRINT CAM CLUTCH SHAFT

Now that the carriage is out of the machine, I had easy access to the three bolts on each side for the bearing caps holding down the print cam clutch shaft and the print wheel drive gear shaft. However, I took a careful look and found parts that were attached to both sides of the divide where the bearing cap would come apart. Not mentioned at all in the maintenance instructions. 

Yellow circles around first part spanning cap

I continued to find spanning parts and removed the screws for each one until I judged I could get a clean separation of the bearing caps. Removing the caps was easy, giving me access to the two shafts.

I examined the ends closely to be certain that nothing else had to be disconnected before I pulled the print cam clutch shaft out of the frame. 

Once I was ready, the actual lift out and carry of the Print Cam Clutch shaft was easy. It was surprisingly heavy but I set it up on the workbench, ready to work on the Print Clutch Dogs. 

PRINT CLUTCH AND PRINT CLUTCH DOG WORK ADDRESSED NEXT

I slid each clutch off the 18 flute print clutch shaft, got oil on the pivot point for the dog and exercised it to be certain it moves cleanly. I also verified that the clutch itself rotates around the shaft when the dog tooth is not engaged in a flute. 

This needs to be repeated 120 times (119 since the last column is partially removed). I finished about 40% of the columns today - it isn't difficult at all, just requires time to carefully move each disk to the left. It is easy to pop the dog off the pivot, but fortunately also easy to get it back on. 

FIRST LOOK AT THE CARRIER ASSEMBLY

The carrier assembly has an electric motor, a gearbox, clutches, two solenoids, and the carriage control tape mechanism. First up was a good cleaning - removing nut shells and other infestation consequences.

The nut was about 3/4" long, just sitting inside the carriage assembly.

 Visually, the entire assembly appears to be in pretty good shape. I could manually engage the two solenoids and either trigger the slow speed (one line) or high speed (skip) clutches. All parts move freely.

I anticipate that I can do a bit of lubrication and then test this out by energizing the 48V carriage motor. Some of the mechanism turns continually, but the two clutches are what couple the motor drive to turn the platen. Since they are also 48V, should be easy to bench test the carriage completely. 

CLEANED UP THE PLATES THAT SIT UNDER/AROUND THE CARRIER

The black painted plates had decades of rodent feces and urine crusting the surfaces. I did some scrubbing and cleaning, making them considerably cleaner and nicer looking. There is still a sludge on the surface that would take far too much work to remove than I am willing to invest. 

Freeing up 1132 printer components - part 6

TURNING METAL RULER INTO PRINT WHEEL ALIGNMENT TOOL

The only diagram mentioning the Service Tool is below:

I did find the part that I believe is the Service Tool from the text, but it was named the Aligner - Type Wheel in a diagram in the parts catalog. 

The notch in the Aligner (circled in blue) fits over a button (circled in green) on each side of the print wheel assembly. The Aligner has an edge that extends between two characters on the print wheels, blocking the wheels from rotating when the assembly is pulled up by the two handles. It fits between the letters E and R on the wheel, which are adjacent in the arrangement around a wheel.

The characters are raised sections on the top of the teeth of the print wheel, The shoulders of the teeth mesh with the drive wheel below. It is into the shoulders between the R and E teeth that the alignment tool will fit. 

I bought an inexpensive aluminum ruler from the local hardware store, then cut it to length so it will fit a bit past the two buttons on the print wheel assembly. I notched out a slot on each side that will slide onto the buttons, with the edge of the ruler fitting into the shoulders of the print wheels. I then had to hold it down in place with zip ties to be sure that it kept the wheels locked in alignment. 

With the wheels locked, it was easy to remove the bolts and lift the print wheel assembly out of the printer. I had access to make sure the wheels and hangar pivots were well lubricated. 

The wheels turn freely and all the hangars pivot. The surfaces of the print wheels are rusty but that will go away after a few minutes of printing. This assembly needs no further restoration or lubrication. 

MORE DISASSEMBLY TO AID IN FREEING UP PRINT CLUTCH AND LATCH

I decided to do more disassembly of the printer mechanism in order to easily get to and manipulate the Print Clutch Dog, Print Clutch plate and Print Clutch Latch parts. I looked at the maintenance manual for the procedure to remove the print clutch shaft which would do the job. However, the procedure looks quite intensive.

By analogy, imagine reading the procedure to repair a part in an automobile, only to be told to remove the engine, transmission, doors, seats and all four wheels before reaching the part. On the printer, I have to remove the entire print carriage first. Next I would remove the print wheel assembly, which requires me to build an alignment tool first and install it to lock the wheels in the proper orientation before removal. Other parts come out before I could begin to remove the shaft in question with the print clutches on it. 

Among the parts I had to remove were the top cover, the side covers, the top back cover and two metal plates that sit around the carriage for cosmetic reasons. The last of those plates was challenging to get it. I ended up having to lift up one end of the carriage when I had unscrewed it (see below) then slid the plate partway under it to get it out of the machine. 

Clutch cam shaft and print wheel drive gear

REMOVING CARRIAGE

The instructions for removing the carriage are vague and have some internal contradictions. The manual says only to:

When necessary to remove the carriage, it should be done by removing the two large tip-up shoulder screws, one at each end. (Figure 4-14.) 

The problem here is that the diagram shows no screw labeled Tip Up Shoulder Screw and there does not seem to be any single screw on a side. The only possibility is that the Carriage Removal Screws from the diagram are in fact the Tip Up Shoulder Screws. However, the diagram makes this appear to be two screws on a side, one coming in from each end, which doesn't agree with the claim there is ONE screw.

Looking at the left side of the carriage, if there were two bolts, front and back, as the diagram shows, then the front bolt is directly blocked by the timing disk. That would be a real pain to take apart just to get the carriage off.

Timing disk in front of shoulder bolt

To lift the carriage I needed to take the entire top cover off of the printer, giving me the room to pull the carriage directly up. I then discovered wiring connected to the carriage which had a connector inside the carriage that I could pull off to disconnect the wiring.  There was also a ground strap that would have to be detached in order to lift the carriage out. None of that was documented in the maintenance manual. According to that manual, all you need to do is remove the two screws. Hah. 

Plate to remove, blocked by carriage

Wires running to carriage

Plug disconnected

Ground strap

Top back and sides removed

When I could finally see the Carriage Removal Screws that I was unfastening, it was clear that the screw is in fact a single long bolt that is only threaded at the end, rather than two screws as it appeared in the IBM diagram. 

Removing shoulder bolt

I was initially concerned 

The carriage assembly is pretty heavy and awkwardly shaped. I am going to work out a method sliding a board underneath it, then slide the carriage out one side of the printer. The alternative would require two people to safely lift it out. 

REMOVING PRINT CLUTCH SHAFT

I had already removed a bar with a comb that kept the 120 print clutch cams spaced evenly. This will be inserted over the restored clutch cams when I am ready to reinstall, held in place temporarily by strings, and used to keep all the Print Clutch Dogs inserted on their Print Clutch Cams during the insertion. 

Again the manual becomes vague: 

Remove the bearing caps after removing the three screws in each. 

There are no illustrations to show where these are, nor the three screws. Nothing in the maintenance manual, the theory of operations manual, or the parts catalog. I had to work this out by examination. It does require the carriage to be lifted out first since one of the three bolts is blocked by the carriage. The caps are shown in yellow below with the three screws under the red arrows.

The actual bearing caps in the machine can be seen with one of the three bolts not visible as it is under the carriage:

I ran out of time in the shop to finish pulling the carriage out thus couldn't unbolt the bearing caps to get at the print clutch shaft. Those bearing caps also hold the print wheel drive gear; these are very large metal pieces. Next time I will pull the bearing caps and then lift the print clutch cam shaft out of the machine to work on it at the bench.