ZK T4 / XLS Bio Prism Replacement
Step 1. Flip the clock over and remove the 4 Philips screws located at each corner.
Step 2. Gently lift the back off the clock straight up and away from the front of the clock, there will be wires attached to both sides of the clock. There is no need to disconnect these wires.
Step 3. Remove the two screws that are mounting the retaining clip to the prism housing, and gently remove the retaining clip. With the retaining clip removed, you will be able to remove the prism housing by gently pulling upward.
Step 4. Remove the housing from the clock and place it on a clean surface, gently set the back of the clock down. Remove the screw holding the back of the housing and slide the backing out, exposing the prism.
Step 5. With the prism exposed firmly press on the back of the prism to pop it out of the housing.
Step 6. Set the new prism in place by lining it up with the housing and firmly pressing it in place. Please note, you should use gloves when handling the new prism to avoid getting oil and fingerprints on the back of the prism’s surface.
Step 7. Follow the disassembly steps in reverse to reassemble the clock.