LiftMaster K2A0878 Hall-Effect / RPM Encoder Board — SL3000U / UL

The LiftMaster K2A0878 is the Hall-effect / RPM encoder board identified in SL3000U-series service information for the operator’s internal motion-feedback system. The associated RPM cup is a separately numbered component, so the electronic sensing board and the rotating target should be checked independently. Match the complete operator generation and installed board reference before ordering. This board is not an external photo eye, a main control board or a universal sensor for all LiftMaster gate and garage door equipment.

Compatibility — Models, Versions and Exclusions

Diagnose Feedback and Mechanical Movement Together

A drive-feedback fault can arise from the sensor, its connection, associated wiring or a mechanism that is not moving correctly. Have the technician inspect these together before choosing the kit. A stalled motor or binding gate can prevent the expected feedback even when the sensing component itself remains serviceable. Record diagnostic behavior rather than assuming every motion-related fault requires a new sensor.

Photograph the installed encoder, RPM cup and connections before service. Compare the actual arrangement with the correct SL3000 generation’s drawing, particularly if earlier repairs changed the electronics. Restore the specified sensing position and wiring without improvising brackets or bypassing feedback. After replacement, complete the prescribed setup and observe the complete operating cycle with the required protection devices functioning.

Specifications and Product Identification

Before Ordering

• Read the complete SL3000 model and encoder label.
• Match K2A0878 in the correct generation’s drawing.
• Inspect the RPM cup, connections and actual drive movement.
• Confirm current board-package contents and post-service tests.

Package Contents and Separate Requirements

This offer identifies the K2A0878 encoder board. The K13-32087 RPM cup, motor, main control board, complete harness and operator are not promised as included. Confirm supplied mounting or connection pieces in the current service package. A feedback fault can require more than one repair, but neighboring parts in the service drawing remain separate purchasing decisions unless expressly included.

Safety Warnings — Read Before Installation or Service

• WARNING: Gate drives contain hazardous electrical energy and exposed moving parts. Feedback-sensor service requires a qualified gate technician.
• Isolate all applicable power and secure the gate before accessing the sensor or control enclosure.
• Never bypass feedback, limits or protection inputs to force a faulty operator to run. Correct the underlying problem.
• Restore guards and verify travel, reversal and every required protection device before returning the entrance to normal use.

Related Products and Important Differences

• 041C4398A residential RPM sensor — a different application; not a substitute for this SL3000 encoder board.
• LMRRUL monitored photo eye — external protection where approved; it does not replace internal motion feedback.

Frequently Asked Questions

Is the RPM cup included?

It is a separately numbered component and is not promised with this board offer.

Does it replace the main control board?

No. It is the internal encoder-board service item.

Will it fit a residential opener?

No cross-application compatibility is established.

Does a feedback error prove the board is defective?

No. Connections, the cup and actual drive movement need diagnosis.

Need Help Confirming the Right Product?

Contact Garage-DoorParts.com before ordering. Send the full equipment model, readable part labels and photographs of the installed assembly. Include the dimensions, electrical configuration or accessory details relevant to your project so the listing can be checked against the actual installation.