Cooling fan
Common VFD, drive, UPS, and cabinet overheating failure point.
Mitsubishi FR-A800 Fault E7 — What It Means
Fault E7 on a Mitsubishi FR-A800 drive indicates a CPU fault — the main control processor has detected an internal error, a memory checksum failure, or a watchdog timer expiration. The FR-A800 is Mitsubishi’s advanced industrial inverter series, featuring built-in PLC functionality, safety inputs, and fieldbus options. E7 is a critical fault that immediately stops the drive output and prevents restart. Unlike most VFD faults which point to external causes, E7 typically indicates a hardware failure within the drive itself — most often a result of a power supply disturbance, a firmware corruption event, or aging control board components.
Common Causes
- Control power supply instability — A momentary drop or spike in the drive’s internal control power supply (usually ±5V, ±15V) can corrupt the CPU’s working memory and trigger E7.
- Firmware corruption — A power interruption during a parameter write or firmware update can corrupt the non-volatile memory, causing the CPU to fail its self-test on the next boot.
- Control board component failure — Aging electrolytic capacitors on the control board degrade the internal power supply rails, leading to intermittent CPU faults that become permanent over time.
- Electrostatic discharge (ESD) — Improper handling of the control board or a discharge event through signal wiring can damage the CPU or its supporting components.
- Excessive vibration — High-vibration environments can cause solder joint fatigue on the control board’s BGA or fine-pitch components, producing intermittent CPU errors.
Step-by-Step Fix
- Power cycle with a long wait — Disconnect all power to the FR-A800 (main power and control power if separate). Wait at least 5 minutes for all capacitors to fully discharge. Restore power. Some CPU faults clear after a complete power cycle if they were caused by a transient event.
- Check for a firmware update event — If E7 appeared immediately after a parameter copy or firmware update attempt, the firmware image may be corrupted. Attempt to re-flash the firmware using the FR Configurator2 tool if the drive will accept USB connection.
- Inspect control board capacitors — With power off, visually inspect the control board for capacitors with bulging tops or brown/dark staining at the base — both indicate electrolytic failure. Replace the control board if damaged capacitors are found.
- Check input power quality — Use a power quality analyzer to verify the supply voltage is stable and free of severe voltage spikes or harmonics that could disturb the internal power supply.
- Contact Mitsubishi FA Support — E7 is a fault code that Mitsubishi service engineers should evaluate. They can read the internal CPU diagnostic log via FR Configurator2 to identify the specific sub-cause.
- Replace the control board or drive — If the CPU fault is persistent and the board shows no obvious damage, a control board swap (or full drive replacement if the board is not available as a spare) is the practical solution.
Parts Often Needed
| Part | Notes |
|---|---|
| Control PCB (FR-A800) | Frame-size specific; source from Mitsubishi FA or authorized distributor |
| Drive (replacement unit) | For older FR-A800 units where control board availability is limited |
Technician Tips
When diagnosing VFD faults, always check the drive’s fault history before resetting. Modern drives store the last 5-10 faults with the drive state at the time (running, accelerating, decelerating, stopped). An overcurrent fault that occurs only during acceleration points to incorrect motor data or mechanical binding. The same fault during deceleration suggests regeneration issues. A ground fault that clears after disconnecting the motor and returns when reconnected means the motor or cable insulation has failed.
Prevention: Schedule annual infrared scanning of drive cabinets. Loose power connections and failing capacitors produce heat long before they cause faults. A 5-minute scan can prevent hours of unplanned downtime.
Need Replacement Parts?
Before ordering, match the drive part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
E7 almost always requires a Mitsubishi-certified drive technician. Unauthorized firmware loading or improper control board replacement can permanently damage an FR-A800. Contact Mitsubishi Factory Automation technical support for E7 diagnosis.