Troubleshoot the Tecan MCA96: Missing Volume Pipetting Issues

[Quick Answer] The Fast Fix

If your Tecan Freedom EVO is missing volumes across entire rows or columns, it is usually because the MCA96 arm is out of alignment.

• The Symptoms: Intermittent failure to pipette correctly across specific rows or columns.
• The Solution: An inspection of structural screws, a full range check, and a Reference Position Setup by our engineer to realign the head.
• Single Well Issues: If the same well always fails, it’s likely a worn O-ring or a specific channel malfunction requiring a seal replacement.

The Problem: Patterned Pipetting Failures

An intermittent issue with the MCA96 arm can cause incorrect pipetting, leaving entire rows or columns under-filled or empty. Because the failure often moves between different wells or plates, it can be difficult to predict or isolate during a standard run.

Solution 1: Mechanical Realignment of the MCA96

Missing volumes in rows or columns indicate the head is not sitting perfectly square to the deck. This tilt prevents tips from seating with uniform pressure, causing air leaks during the aspiration cycle.

To resolve this, our service engineer performs a mechanical recovery protocol.

• Hardware Inspection: Tightening structural screws on the MCA arm to eliminate any "sag" or mechanical play caused by vibration.
• Range Check: Verifying the full X, Y, and Z travel to ensure there is no hidden resistance or motor slipping.
• Reference Position Setup: Executing a service-level recalibration to reset the arm's home coordinates. This ensures the MCA96 "knows" exactly where it is in relation to the deck for perfect tip seating every time.

Solution 2: Channel-Specific Repair

If a specific well consistently fails to pipette correctly, the issue is likely a localized vacuum seal breach rather than a general arm alignment problem.

• O-Ring Replacement: Swapping the worn or compressed seal for that specific channel to restore suction.
• Head Evaluation: Assessing the internal manifold if O-ring replacement fails, which may indicate the need for a full MCA96 head replacement.
  

FAQ: Maintenance & Calibration

Is a Reference Position Setup the same as Labware Teaching? No. Labware teaching tells the arm where the plate is, but a Reference Position Setup tells the arm where the arm itself is. If the arm's internal reference is off, your labware teaching will never be consistent.

Why does the volume loss affect entire rows? Even a fraction of a millimeter of misalignment prevents tips in that row from making a proper seal with the manifold. This "tilt" leads to failed aspiration across the entire section.

Can I fix this myself? Mechanical alignment and Reference Position Setups require specialized service software and tools. Our engineer should perform these steps to avoid accidental crashes or further hardware damage, ensuring your instrument returns to validated specifications.

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