Tension Cord Replacement Guide
This procedure describes how to replace the long and short tension cords in a PAL injection unit.
Regular replacement helps maintain correct syringe slider positioning and proper vial or well plate pressure during operation.
- ESD Warning: Disconnect the PAL system from power and unplug all connected devices (PC, GC, LC) before starting maintenance.
- ESD Protection: Use an ESD strap when touching electronic components to prevent PCB damage.
- Remove the Injection Unit (“Head”) from the Y-axis. Move the slider assembly to access the three mounting screws (Torx T20).
- Carefully disconnect the ribbon cable and avoid pulling it too far out of the head assembly.
- Remove the top cover plate by loosening the top screw (Torx T10).
- Release and remove the long tension cord that keeps the syringe slider assembly in position when power is off (recommended replacement: annually).
- Place the PAL head with the syringe slider assembly on a clean workspace.
- Pull the black syringe slider assembly out of the Z-axis.
- (CombiPAL only) Remove the PAL MZAgiOpen bumper.
- Remove the five screws securing the electronics and needle guide cover plate (Torx size 8 recommended).
- Remove the cover to access the electronic components and needle guide mechanism.
- Disconnect the short tension cord by stretching and removing it. This cord presses the vial or well plate down when the syringe is withdrawn (replace annually).
- Install the new short tension cord so the knot faces away from the electronic board (~60° angle) and ensure the needle guide moves freely.
- Reinstall the metal cover and verify correct positioning of the flush tube relative to the roller (CombiPAL only).
- Insert the syringe slider back into the injection head and push it fully upward until the upper roller pair becomes visible.
- Tighten the five screws securing the electronics cover plate.
- Reinstall the PAL MZAgiOpen bumper and secure it with two screws.
- Use tweezers to reconnect the long tension cord to the top cover of the injection head.
- Reattach the injection head to the Y-axis, reconnect the cable, and tighten the three mounting screws.
