WP 11678

Issues reported with the EX Picomotor Driver. Found chassis breaker in off position and would immediately trip if chassis was switched on. Unit removed and taken to EE lab. Found one of the 8702 Newport picomotor PZT drivers shorting the 24V power line. No spare Newport 8702 PZT drivers available. Spare chassis installed.

Steps taken before powering on spare unit.

1. Field cables tested for shorts; no issues found:
   1. Across pins 1&14, 2&15, 3&16, 4&17, 5&18, 6&19, 7&20, 8&21
   2. All pins to chamber/table ground
2. Unit powered on with no cables connected.
3. Beckhoff controls and readback cables connected and unit powered up.
4. Connected spare picomotors X&Y and tested all channels using the RJ9 front panel jacks. All channels tested fine.
5. Disabled EX Picomotor (MEDM) and reconnected field cabling.

Picomotor Driver S1107566 Removed
Picomotor Driver S1107550 Installed