The Problem
An Agilent 6890 GC autosampler was unable to initialize and could not perform injections because of a Z-axis homing error. A replacement injection tower had already been installed, but the fault remained, indicating that the issue was elsewhere in the autosampler system.
Diagnostics
ScientifiCo evaluated the remaining autosampler components, with attention to the carousel tray assembly and sample handling motion. Inspection showed that the carousel drive belt was torn and could no longer transmit motion reliably.
The belt was replaced using a customer-provided part. After reassembly, the carousel still failed to operate, and additional diagnostics showed that the carousel drive motor was not activating as expected.
Verification With Known-Good Assembly
To separate a tray failure from a tower or controller issue, a known-good carousel tray assembly was installed for comparison testing. With the known-good tray in place, the autosampler initialized normally and the axis errors cleared.
Result
The test confirmed that the customer’s original carousel tray assembly had failed internally. The replacement injection tower was functioning correctly, and the known-good tray restored autosampler initialization and injection readiness.
