What the A.7A0 alarm means

The SERVOPACK heat-sink temperature exceeded 100 degC; the drive derates or shuts down to protect the power electronics. We have built up many handled cases of this Yaskawa DX100 / DX200 / YRC1000 alarm, and usually the first on-site inspection tells us what is wrong.

Most common causes

  • Cabinet cooling fan failure or clogged filters
  • Ambient temperature above 55 degC
  • Sustained overloading of the axis
  • Repeated overload-alarm resets without cooling time
Field note: Confirm or rule out the first cause first — it is the situation we encounter most.

Step-by-step field fix

  1. Let the drive cool naturally — do not reset repeatedly
  2. Clean or replace cabinet filters and verify fan operation
  3. Lower the ambient temperature or add ventilation
  4. Review the duty cycle for sustained peak loads
  5. Replace the SERVOPACK if overheat recurs under normal duty
Safety first: For YASKAWA a-7a0, this alarm family involves the DC bus, which sits at several hundred volts and stays charged for minutes after power-off - touching terminals is a shock hazard. The self-serviceable action is Let the drive cool naturally — do not reset repeatedly; anything past that falls under the DC bus and power stage and needs a certified engineer. On YASKAWA a-7a0: checking incoming voltage at the disconnect and looking at breakers and fuses is fine to do yourself; opening the cabinet to touch bus terminals or pulling power modules needs a qualified electrician.

How we diagnose drive alarms on site

YASKAWA a-7a0 belongs to the drive & power stage family. On YASKAWA a-7a0 the failing stage is Yaskawa Sigma-series servo drives (servo packs) assigned per axis in the cabinet on the DX100 / DX200 / YRC1000 / YRC1000micro - the fault sits on the energy chain: mains input, rectification, DC bus, braking resistor, inverter power devices and the drive board. We start reading YASKAWA a-7a0 at the pendant alarm list (A / E / 4xxx segments) together with the servo drive's digit display.

The chain involved in YASKAWA a-7a0 runs: three-phase mains -> rectifier -> DC bus (bus capacitors) -> brake chopper / braking resistor -> inverter (IGBT) -> motor.

Cabinet cooling fan failure or clogged filters is common on YASKAWA a-7a0, but look at the duty cycle: Cells with high-inertia loads or frequent start-stop cycles return far more regenerative energy than a plain transfer cell, and the braking resistor lives in a hot cycle that shortens its life. When we suspect this family we ask what changed: if the takt was raised recently or a heavier fixture went on, the alarm cluster usually lines up with that process change. Replacing the resistor alone will not fix it - the chopper rating and resistor wattage have to be re-checked against the new duty.

Field notes on this page cover YASKAWA a-7a0 (Heat Sink Overheated (>100 degC)); written by the Henghuan repair team, updated 2026-10-01.

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Related Drive & Power Stage alarms

A.100 — Overcurrent or Heat Sink Overheated (SERVOPACK) A.320 — Regenerative Overload A.400 — Overvoltage — Main Circuit DC Voltage Too High A.410 — Undervoltage — Main Circuit DC Voltage Too Low A.710 — Overload — High Load (Stall-level Torque) A.720 — Overload — Low Load (Continuous Over-torque)
Same family: this code belongs to the Drive & power stage alarms family - the page collects all Drive & power stage-family codes we have handled, with the common inspection order and spares.
Other brands: we also keep field-fix libraries for Universal Robots · Kawasaki · Staubli and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the YASKAWA a-7a0 alarm mean?

The SERVOPACK heat-sink temperature exceeded 100 degC; the drive derates or shuts down to protect the power electronics. We have built up many handled cases of this Yaskawa DX100 / DX200 / YRC1000 alarm, and usually the first on-site inspection tells us what is wrong. YASKAWA a-7a0 sits in the drive & power stage family; on our work orders the highest-frequency trigger for this code is "Cabinet cooling fan failure or clogged filters".

QCan I clear a YASKAWA a-7a0 alarm myself?

Whether YASKAWA a-7a0 clears on its own depends on the outcome of "Let the drive cool naturally — do not reset repeatedly". Finish the flow with "Replace the SERVOPACK if overheat recurs under normal duty" to confirm YASKAWA a-7a0 - do not skip it. If that step is clean, the second most frequent cause on YASKAWA a-7a0 is "Ambient temperature above 55 degC". If YASKAWA a-7a0 returns after two clears, or the checks point at Cabinet cooling fan failure or clogged filters, stop the cell and call a professional robot repair engineer.

QFor drive/power alarms like YASKAWA a-7a0, what spares do you bring on site?

The commonest causes we see on YASKAWA a-7a0 are "Cabinet cooling fan failure or clogged filters, Ambient temperature above 55 degC, Sustained overloading of the axis", so we stock the van against those. For YASKAWA a-7a0 specifically, we stock the van along the energy chain: braking resistors, bus capacitors, input fuses, drive-board supply parts and the common power modules for the brand. For YASKAWA a-7a0, drive alarms usually stop the whole line, so they sit at the front of our dispatch queue. Before we roll, tell us what YASKAWA a-7a0 shows on the pendant alarm list (A / E / 4xxx segments) together with the servo drive's digit display and what the machine was doing - phone or video triage is free.

This page on YASKAWA a-7a0 was written by the Henghuan Robotics repair team from field service experience. Alarm descriptions are our own summary for troubleshooting reference and may vary by controller and software version — when in doubt, check your Yaskawa documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by Yaskawa.