❓ Question — from a lathe operator, Ludhiana
We changed the servo battery on our Mitsubishi M80 lathe (MDS-E drives) and now get Z71 (Abs encoder: initial position lost) on X and Z. How do we set zero again safely? The turret is close to the chuck.
✅ Answer — JJ Automation Technical Team
Z71 means the absolute encoder lost its backup while the battery was disconnected — position data is gone, the encoder itself is almost certainly fine. To re-establish zero:
- First move the machine to a safe area in handle/jog mode (the alarm usually still allows jog). Move the turret well clear of the chuck and tailstock.
- Open Maintenance → Parameter and set #2049 (type) for the axis to the zero-point initialization method your builder used — most Indian-market lathes use marked point / no-stopper (type 2: basic point alignment).
- In Absolute Position Setting screen (Maintenance → Abs pos), select the axis, set "Abs posn set" = 1, jog the axis to the builder's reference mark (scribe line / dial position from the machine manual).
- Set the origin/zero — the screen shows "complete" when position is latched. Repeat per axis.
- Power cycle the CNC completely (main breaker, not just NC reset). Z71 should clear.
If Z71 returns after every power-off with a NEW battery: measure the battery voltage at the drive connector (should be ~6V for MR-BAT6V1 type) and check the encoder cable's battery wires for a break — a common failure on flexing cable tracks.
Reply below with your machine make and #2049 setting if the procedure doesn't match your screen — M700/M800 differ slightly and we'll post the variant.