Troubleshooting Mori Seiki SL-25 EX0980 Lock Pin Alarm

EX0980 Not Lock Pin In is an interlock fault, not a prompt for a universal unlock code. On a Mori Seiki SL-25 fitted with the spindle lock-pin system, the control must see confirmation that the hydraulic pin reached its commanded position. Clear the alarm by restoring pin movement, position feedback, or spindle-index alignment.

Machine Configuration and Safe Starting State

Before anything else, confirm that the machine has the lock-pin assembly described here: a small hydraulic actuator at the rear of the spindle that inserts a pin into a spindle slot and prevents rotation. This arrangement points to an SL-25 configuration with spindle indexing, possibly an early SL-25M with an indexable C-axis. Record the complete model and control identification before looking for parameters because the control type is not specified.

1. Stop automatic operation and remove any spindle command.
2. Place the machine in the manufacturer-defined maintenance state before reaching the rear spindle area.
3. Inspect the electrical prints and hydraulic diagram. Identify the lock-pin solenoid, proximity-switch feedback, and related relay output by function; no I/O addresses are established here.
4. Observe whether the pin is retracted, partially inserted, or fully inserted while the message is active.

Do not move on until the physical pin position and the corresponding diagnostic input state have both been recorded.

Lock-Pin Travel and Spindle-Slot Alignment

The first split in the diagnostic path is whether the actuator moves. A pin that travels but stops short usually indicates slot misalignment, binding, contamination, or inadequate hydraulic force. A pin that never starts moving directs the work toward the solenoid and electrical output path.

Inspect the pin and slot for burrs, chips, visible damage, and side loading. Check hydraulic pressure against the value printed on the machine documentation rather than substituting an assumed setting. Do not force the pin or rotate the spindle against an engaged pin. Continue only after the pin can travel freely to the seat when the slot is aligned.

Proximity-Switch Feedback

The control can display EX0980 even when the pin appears inserted if the proximity switch does not report the seated position. The switch may be out of adjustment, its target gap may be excessive, or its wiring and input circuit may have failed.

1. Locate the proximity switch associated with the lock pin in the electrical prints.
2. Monitor its control diagnostic input while moving the mechanism only through an approved maintenance command.
3. If access is safe, present a suitable metal target to the sensing face as a diagnostic test. This checks whether the sensor can switch independently of pin travel.
4. If the input changes with the test target but not with the seated pin, correct the mounting, target alignment, or sensing gap using the sensor and machine documentation.
5. If the input never changes, check sensor indication, supply, connector condition, wiring continuity, and the receiving input channel.

A metal target is a test tool, not a permanent bypass. Do not proceed until the feedback input follows actual pin position and drops out again when the pin retracts.

Solenoid and Bestac Relay Output

If the pin does not move, trace the command from the control output to the hydraulic solenoid. An early SL-25M arrangement may use a Bestac relay card to control the pin solenoid. That machine arrangement has three such cards, which can provide a substitution test when the cards are electrically interchangeable.

1. Command lock-pin insertion and check whether the control requests the output.
2. Check the associated relay indication and determine whether the solenoid receives its commanded supply. Use the electrical prints to select the test points and expected voltage.
3. If the command exists at the control but not at the solenoid, inspect the Bestac relay card, connectors, wiring, and intervening protection.
4. For a card-substitution test, power down according to the machine procedure, label every connector, and verify from the prints that the candidate cards have matching functions and connections before exchanging them.
5. If the fault follows the card, repair or replace the failed relay hardware. If it remains with the lock-pin circuit, restore the cards to their original positions and continue through the field wiring and solenoid.

Do not move on until a lock command energizes the solenoid and produces repeatable actuator movement.

Index Position and Grid-Shift Correction

When the actuator, output, and sensor are functional but the pin meets the spindle instead of entering the slot, check the commanded spindle index position. On an indexable C-axis configuration, the grid-shift setting influences where the axis settles relative to the mechanical lock position.

1. Mark or measure the relationship between the stopped spindle slot and the pin centerline.
2. Repeat the index command to determine whether the offset is consistent. A changing stop position points away from a simple grid-shift correction and toward the positioning system.
3. Verify reference return, feedback condition, mechanical coupling, and index repeatability before changing a parameter.
4. If the offset is stable and the machine procedure identifies grid shift as the correction, back up the parameters and record the original value.
5. Adjust only by the documented control method and increment. The control model and grid-shift parameter identifier must come from the machine documentation.

Do not use grid shift to compensate for a sticking pin or failed proximity switch. Proceed when repeated index commands place the slot on the pin centerline and the pin seats without contact against the slot edge.

End-to-End Interlock Verification

1. Command the spindle to its required index position and confirm repeatable slot alignment.
2. Command the lock pin in. Confirm the solenoid output, full mechanical travel, and transition of the lock-pin diagnostic input.
3. Verify that EX0980 Not Lock Pin In clears only when the pin is seated and its feedback is active.
4. Command retraction and confirm that the input changes state before spindle motion becomes available.
5. Repeat the complete insert-and-retract sequence several times from normal operating commands. Stop testing if travel becomes slow, alignment changes, or feedback becomes intermittent.

The repair is proven only when spindle positioning, pin travel, sensor feedback, alarm clearing, and release for the next machine action occur in the correct sequence without a temporary sensor target or forced output.

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