What is a servo press?

A servo press uses servo motors for precise force and position control during forming operations.

How do I calculate servo press tonnage?

Use our free tonnage calculator at servopress.club/tonnage-calculator.html

Mitsubishi MR-J4 AL.E3 Alarm: Absolute Position Lost on Servo Press

admin

AL.E3 on Mitsubishi MR-J4 servo drives indicates absolute position data has been lost. On a servo press, this is critical because the press cannot determine slide position without absolute encoder data.

## Why AL.E3 Occurs

The MR-J4 uses a multi-turn absolute encoder that retains position data through a battery backup. AL.E3 triggers when:

1. **Battery voltage too low** —encoder battery below 3.0V (nominal 3.6V lithium)
2. **Battery disconnected** —cable unplugged during maintenance
3. **Encoder cable disconnected** with power off —absolute data lost
4. **First power-on** after encoder replacement

## Battery Replacement Procedure

The encoder battery is located on the servo motor, not the amplifier.

1. Power on the servo system (battery replacement must be done with power ON to preserve data)
2. Locate battery connector on motor encoder —typically a small JST connector
3. Replace with MR-BAT6V1SET (3.6V lithium, Mitsubishi part)
4. Do NOT power off between disconnecting old battery and connecting new one
5. Verify AL.E3 clears after replacement

**Battery life:** 3-5 years at 20?C. Replace every 3 years as preventive maintenance.

## Absolute Position Recovery After AL.E3

After clearing the alarm, the press does not know where the slide is. You must perform home position recovery:

1. Manually jog slide to mechanical home position (TDC)
2. On MR-J4 amplifier: hold SET button for 3 seconds to set current position as home
3. Alternatively, use MR Configurator2 software: Diagnosis > Absolute Position > Set Home
4. Verify position on press HMI matches expected TDC value

## Preventing AL.E3

- Add battery replacement to annual PM schedule
- Monitor battery voltage via MR Configurator2 (Diagnosis > Battery Voltage)
- AL.92 (battery warning) appears before AL.E3 —replace battery immediately when AL.92 appears

anna_controls

AL.E3 recovery on MR-J4 requires careful attention to the homing sequence. After replacing the battery and clearing the alarm, you must jog the slide to the mechanical home position (usually TDC) using the manual pulse generator at minimum speed. Then write the home position value using parameter PA03. Do not skip this step or the absolute position reference will be wrong.

raj_maintenance

AL.E3 recovery procedure for MR-J4: 1) Replace battery if voltage is low. 2) Power cycle the drive. 3) If AL.E3 persists, you need to re-establish the absolute position by jogging to a known reference point and writing the position value. On a press, this means carefully jogging to TDC using the manual pulse generator. Do NOT rush this step.