TL;DR

Alarm 108 on the Haas VF-2 means the Automatic Pallet Changer (APC) has reported an excessive fault. The fix is to acknowledge the alarm, power-cycle the machine, then inspect the APC proximity sensors and connector J10 for debris or loose pins.

What you might see

alarm 108
APC excessive fault
pallet changer error
haas alarm code 108

Likely causes

Tap to mark as ruled out

Debris obstructing APC proximity sensors
Loose or contaminated pins on connector J10
Misaligned proximity sensors after a crash

Required tools

Lint-free cloth
Phillips screwdriver
Multimeter (optional)

Safety first

Lockout-tagout the machine before opening the electrical enclosure.
Allow the spindle to come to a complete stop before reaching into the work area.

Procedure

7 steps · ~15 min

1
Press RESET on the control panel to acknowledge the alarm.[1]
Control Panel Layout
Haas VF-2 control panel — RESET button highlighted
- RESET Button
- ALARM Display
- Mode Switch
2
Navigate to ALARMS > ACTIVE ALARMS to confirm the message reads 'Alarm 108: Excessive APC Fault'.[1]
3
Power cycle the machine: turn the main breaker OFF, wait 30 seconds, then turn it ON.
Warning: Lockout-tagout the machine before opening any electrical enclosure.
4
If the alarm persists, check the APC proximity sensors for debris and clean with a lint-free cloth.[1]
5
Inspect connector J10 on the APC motor for loose or contaminated pins. Reseat if necessary.[1]
6
Run SETTINGS > DIAGNOSTICS > APC TEST to verify all sensor states report PASS.[1]
7
Press RESET once more and resume operation.

Sources

Haas VF Series Operator's Manual, Haas Automation Inc.
Section 7.4 - APC Fault Codes, page 218
View source
“Alarm 108: Excessive APC Fault, see proximity sensor cleaning and connector J10 inspection procedure.”

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