Saturday, June 6, 2015

Still working to get the escapement and CR cords on the 1053 exactly right, plus checkout of the Pertec disk drive


I removed the spring on the carrier return torque limiter and replaced it with the correct spare parts spring, since the torque limiter must be adjusted so that it doesn't produce excessive pull, which could have caused the problem I had.

I have begun the tedious job of installing the escapement and carrier return cords on their respective drums and pulley systems. I need to have this finish up with the carrier at the far right, since that is the position to put the initial tension of five turns on the mainspring.

With everything hooked up, I did some hand cranking of CRs and tabs and it all seemed good. Power was applied to the motor, tabs again good but the CR zoomed all the way to the left, popped the escapement cord off the drum again, and hadn't unlatched the CR clutch as it should have.

I only need to reattach the escapement cord to try some more, but it is going to be necessary to figure out what is malfunctioning before I do the next power return or I will be in an infinite loop of escapement cord reattachment.

I did a few rounds of carefully setting up the cords, drums, mainsprings, pulleys and have come to the conclusion that I need to put more tension on the cords by shortening the carrier return cord. Normally, the tension is adjusted by loosening two screws that hold the CR drum in position on the mainspring shaft, rotating the drum in relation to the escapement drum, but I have a problem.

The mainspring shaft is a bit scraped up so that the setscrews and CR drum are no longer adjustable. I will have to shorten the cord instead of rotating the drum to move the attachment point further. The daylight is fading, so this will have to wait until another day.


The drive won't start - no spinning of the motor, blowers etc. I need to get in and debug this, using documentation from a very similar Pertec drive. I think the documentation I have is from the successor version of my drive, very very similar but some differences that are easy to spot.

The drive, opened up and cartridge removed
This may be simple issues, such as the start/stop signal line on the interface appearing to be active since I don't have any terminators on the cable. It could be that one of the microswitches that signal the presence of a drive is not working. I can be a logic board failure as well. At least all the superficial stuff looks good - fuses are intact, boards in place, connectors inserted properly, no wiring out of place.

The removable disk cartridge (5440 type for top loading) but similar to the front loading 2315 used with the 1130
Two unused cartridges, in box, that were inside the cabinet holding my drive

Unused cartridge in the box


  1. The tension on the Return and Tab cords is set by the spring-loaded Tab Cord Pulley that is outboard of the frame on the right side. Changing the length of the cords (or rotating either drum on the mainspring escapement shaft) just changes the pre-load position of the Tab Cord Pulley. There should be marks on the pulley slide to indicate the correct at-rest position. If the Tab Cord Pulley slide it too far outboard, it won't be able to take up the slack as a Carrier Return happens and would allow the cord to become disconnected.

  2. As long as the Pertec isn't sending out any magic smoke when you plug it in, things can't be that bad. ;-)