Some Shasta synthesizer users have experienced a sudden and significant slowdown during synthesis — sometimes stretching run times from hours to days.
This issue can lead to failed runs and wasted plates if not addressed quickly.
One likely cause is a Y‑axis cable connection issue affecting the movement of the XY Table
How It Happens
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The Shasta’s Top (Y‑axis) movement can stretch or shift the cable that connects to the motor head assembly.
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If the cable is strained or the connector becomes partially loose, the instrument may pause or slow as it tries to complete movements.
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In some cases, this happens at the extreme travel points (furthest left or right positions).
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Even if there’s enough cable slack, certain movement patterns can still shift the connection enough to cause intermittent contact.
Symptoms
You may notice:
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Significantly slower injection times as the run progresses.
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Example: ACN steps that normally takes ~18 seconds may take 6+ minutes later in the run.
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The instrument may freeze over the weekend or after long runs until restarted.
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Y‑axis movements feel delayed, hesitant, or inconsistent.
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Chamber pressure calibration may be off after a freeze.
Troubleshooting Steps
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Review Logs
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Compare early‑cycle and late‑cycle injection times.
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Look for large increases in wash or reagent injection durations.
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Inspect the Y‑Axis Cable & Connector
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Power down the instrument.
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Locate the Y‑axis cable running to the top injection head.
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Gently tug and move the cable to check for looseness or intermittent connection.
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Ensure the connector is seated fully and securely.
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Check for frayed, pinched, or stretched cable areas.
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Check for Obstructions
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Verify nothing is physically impeding the movement of the head along the Y‑axis.
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Ensure cables are routed so they don’t snag during travel.
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Restart the Instrument
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If frozen, restart both the PC and the instrument.
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Perform a chamber pressure calibration to confirm stability.
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Document Findings
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Take photos of the Y‑axis cable and connection.
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Send images and any observations to support@sierrabio.com for review.
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Preventive Tips
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Periodically inspect all motion‑axis cables for wear and secure connections.
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Keep cable slack optimized to avoid excess strain at extreme travel points.
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If slowdown repeats after inspection, consider replacing the Y‑axis cable.
Need Help?
If you continue to see synthesis slowdowns or freezes, please send:
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A brief description of the issue
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Photos of the Y‑axis cable and connector
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Relevant log files
Contact Sierra BioSystems Support at support@sierrabio.com