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.