Pete Dudley, manipulator service technician from CRL, was on site from Nov 27-30 to service the NHC Model N manipulators (See E-log entry #1578 for background).

He began by evaluating the motion selection and electric drive of the manipulator installed on the blue service cart.  This manipulator had chip A0166R01, same as the right side manipulator which had the failure described in E-Log 1578.  Pete noted that the arm was very slow to switch between the different drive directions, and had a significant lag between when the switch for motion was released, and when the motor actually stopped driving.  This was the case with all directions.  Because of this, he suspected that the right arm Z tape broke because when the manipulator reached the switch at the end of travel, the motor did not stop quickly enough causing over tension and snapping the tape.  A newer chip, A0166R04, was removed from the spare master arm (received Spring 2017), and installed into the master arm on the blue cart.  The test was repeated, and this time the motion selection and drive worked as expected.  The situation which previously caused failure was evaluated:  slave end fully extended in Z, master end fully collapsed in Z.  In this configuration the arm was moved back and forth in the Y direction.  No tape failure occurred, and the Z motion tape tension seemed normal.  Y motion drive was attempted, and was not possible, as expected.  This test was repeated in the opposite configuration (slave end fully collapsed, master end fully extended) with the same results.  Full drive speed was used for all tests.

The right side slave arm (with broken Z tape) was then removed and transported to the HCSA.  Using the bench mounted locking plate, the broken Z tape was replaced, and a full inspection and cable/tape tensioning was performed.  Pete accidentally broke the Z tape on the right side master arm while investigating the failure, which was also replaced.

The other two slave arms were also both inspected, tensioned, and tested in the same way.  Then all three were each in turn installed to the master arm #9348 on the blue manipulator transport cart where all mechanical motions and drives were tested (except X, because mounted on cart), the failure situation described above was also tested for all three slave arms.

The left side manipulator was then installed into the wall.  It was necessary to remove the lead sheilding on the thru-tube and machine it down approximtaely 0.070" in order for the arm to fit into the wall tube.  After installation, the manipulator motions and drives were tested again including the X motion, and the failure scenario situation was also re-tested.  Chad used the left side manipulator to remove and re-install the pre-filter mounted on the west side partition wall.  He also confirmed that he could reach the east wall electrical outlets and the outlets, gas fittings in front of the window.

The right side slave arm was adjusted so that the Y position was moved 1/2 turn of the shaft drive towards the window (this is the maximum adjustment possible before it hits a hard stop).  This was done so that the operator can more easily reach the outlets and air/gas connections inside the cell in front of the window.  Because both the master and slave ends protrude further out from the wall compared to the E-HD manipulators for the SHC, this modification makes the NHC manipulators feel a bit more like the SHC manipualtors for the operator.  After the adjustment, the right side slave arm was installed.  The left side slave arm was removed, adjusted the same as the right side, then reinstalled.  The spare slave arm was also adjusted in the same way.

The right side manipulator was evaluated through all mechanical motions.  We attempted to remove the A0166R04 chip from the left side, and install in the right in order to try the motion drives, however the pins had been damaged from the previous removal/install, and eventually one pin broke so this was abandoned.  CRL will ship us at least three new A0166R04 chips which should arrive in 2-3 weeks.

Upon completion of the work the location of the different arms is as follows:  Right side master #9351, Left side master #9348, Spare master #9763, Right side slave #9349, Left side slave #9764, Spare slave #9352