On the Cassini testhead, the inboard u-bar assembly (canoe) contains the latching mechanism. If the latching mechanism experiences a problem, it might be necessary to replace the canoe. This document describes how to perform that replacement.
To remove the old canoe:
- Un-dock and remove any fixtures.
- Turn the testhead power off. On small Cassini, the switch is on the left side, inside the rear door. On large Cassini, the switch is at the bottom of the rack, inside the front door.
- Remove the cover that covers the electronics of the testhead.
- Remove the 2-pin connector from the PCB connector labeled 'Latch'.
- On the testhead, remove 6 each 6-32 screws. Do not remove the 2 each 4-40 screws.
- While holding the canoe, pull the shoulder pin and carefully slide the canoe off of the testhead. feed the wire from the 'Latch' connector out the hole in the side of the testhead.
The canoe is now removed.
Note: With the canoe removed, the testhead is fragile, and the bearings in the remaining canoe can be easily damaged. Do not try to use the latching mechanism. Do not put any pressure on the testhead.
To install the new canoe:
- Pre-align the linear bearings (1 on each end of he canoe) so that the bearing's threaded holes will align to the testhead holes.
- While feeding the wire back through the hole in the side of the testhead, carefully slide the canoe into place.
- Use a small sharp tool to align the linear bearings with the holes in the testhead.
Carefully install the 6 each 6-32 screws.
Note: Because the linear bearing has movement, it is very easy to cross-thread the screws. Start the screws very carefully using a manual screwdriver. If a screw begins to cross-thread, STOP, remove the screw and re-install it properly.
- Connect the wire back onto the PCB Latch connector.
- Install the cover back onto the testhead.
The replacement canoe is now installed and should function properly.