How do I convert a Von Duprin 98/99 series Rim or Vertical Rod/Cable device from classroom function to nightlatch (storeroom) function)?

1. You need NL drive screw if you don't have one.  Part #090074 for a package of 10. This is the set screw that goes in the master cam on the back of the device center case.
2. Remove the NL drive screw from the center case if it is not already removed.
3. With a Phillips-head screwdriver, rotate the master cam on the back of the exit device center case (chassis).  Rotate it so it moves the boomerang shaped locking slide to a DOWN, or locked, position.  This will keep your classroom function lever handle from moving if you are trying to re-use a classroom function trim in nightlatch function mode.
4. Re-insert the NL drive screw.  This will cause the key to only retract the latch bolt, instead of move the locking slide up and down.
    

Reference Video linked here for cam locking slide operation: .  Note: the video shows how to go from NL to classroom function.  This knowledge center entry discusses how to go in the reverse mode of what is shown in the video.