Yaskawa A1000 VFD AL-29 — What It Means
The fault code AL-29 does not appear in any official Yaskawa A1000 VFD documentation or service manual. Yaskawa A1000 drives use specific alphanumeric codes like oH, SC, Uv, and CPF, but no code matching AL-29 is listed in the manufacturer’s fault code tables. If your display shows AL-29, it is most likely a misread code (such as CPF29, which indicates control circuit hardware damage), a custom alarm label created by a third-party monitoring system like a PLC or SCADA, or possibly a display glitch or firmware bug.
The closest valid Yaskawa code ending in 29 is CPF29, which means control circuit error and indicates damaged hardware on the control board. This fault requires a power cycle and typically replacement of the control board or the entire drive unit. Other possibilities include misreading an overheating fault (oH codes) or short-circuit faults (SC codes). Always verify the actual fault code by power cycling the drive and checking the fault history menu (parameter U2-02) to confirm the exact code before ordering parts or calling for service.
Before You Replace Anything
Technicians sometimes replace the entire VFD when the issue is simply a misread code or a third-party system alarm. Always verify the actual fault code in the drive’s fault history menu (U2-02) and check PLC/SCADA alarm mappings before ordering expensive replacement hardware.
Common Causes
- Misread or incorrectly displayed code (~50%) The most common reason for seeing AL-29 is misreading the actual fault code on the display, confusing CPF29 or another valid code, or viewing a custom alarm label from a third-party monitoring system rather than the drive’s native fault.
- Third-party alarm system custom label (~30%) Many PLC or SCADA systems create their own alarm numbering (such as AL-29) that maps to one or more underlying Yaskawa fault codes, so the drive itself may be showing a different code internally.
- Damaged control board hardware (actual CPF29) (~15%) If the real fault is CPF29, the control board has sustained physical damage such as burned components, failed capacitors, or corrupted connections between the control board and drive unit.
- Display glitch or firmware bug (~5%) Rarely, a corrupted display or firmware error can show a nonsensical code like AL-29 that does not exist in the official fault table.
Quick Diagnosis
Answer these to narrow it down fast.
Does the drive display change to a different code after a complete power cycle?
No: The code persists. Check the fault history menu (U2-02) to see if the drive logs a different underlying fault.
Is the drive connected to a PLC, SCADA, or HMI system that shows AL-29?
No: The code is coming directly from the drive. Proceed to verify the exact characters on the drive's own display and consult the fault history.
Does the fault history menu (U2-02) show CPF29 or another valid code?
No: The drive may have a corrupted display or firmware. Contact Yaskawa technical support or a qualified VFD technician for further diagnosis.
Step-by-Step Fix
- Power cycle the drive completely. Turn off input power, wait 60 seconds for capacitors to discharge, then restore power and observe the display for the exact fault code shown.
- Access the fault history menu. Navigate to parameter U2-02 on the keypad to view the last stored fault codes and confirm whether the drive logged AL-29 or a different code such as CPF29.
- Check third-party systems. If the drive is connected to a PLC, SCADA, or HMI, review the alarm mapping configuration to see if AL-29 is a custom label assigned by that system rather than a native Yaskawa code.
- Inspect the control board physically. Disconnect all power and open the drive enclosure. Look for burnt components, cracked capacitors, discolored PCB areas, or loose connectors between the control board and the main drive unit.
- Perform electrical testing on the drive. Use a megohmmeter to check line-to-line and line-to-ground resistance (should be greater than 5 megohms). Measure DC bus voltage between the positive and negative terminals (should be approximately 145 percent of line-to-line input voltage).
- Replace the control board if CPF29 is confirmed. Order the correct control board part number for your A1000 model from Yaskawa or an authorized distributor and install it according to the service manual. If the fault persists after board replacement, the entire drive unit may need replacement.
- Document and consult support if code remains unexplained. If none of the above steps resolve the issue or if AL-29 continues to display without a matching entry in the fault history, contact Yaskawa technical support with the drive serial number and firmware version for further diagnostics.
Parts Often Needed
| Part | Notes |
|---|---|
| Yaskawa A1000 Control Board | Amazon | Verify exact part number for your drive model and firmware version from the service manual or Yaskawa distributor |
| Yaskawa A1000 VFD Complete Unit | Amazon | Required only if control board replacement does not resolve a confirmed CPF29 fault or if multiple internal components are damaged |
When to Call a Pro
Call a qualified VFD technician or industrial electrician if you cannot verify the exact fault code after power cycling and checking the fault history, if the drive is connected to complex PLC or SCADA systems that require custom programming knowledge, or if you confirm a CPF29 fault that requires control board replacement. Control board replacement involves working inside high-voltage equipment with stored energy in capacitors even after power is disconnected, and improper handling can cause electric shock or further damage to the drive. Additionally, if you lack a megohmmeter or experience with DC bus voltage testing, professional diagnosis is necessary to avoid misdiagnosing the fault and replacing expensive parts unnecessarily. If the drive is under warranty or service contract, contact Yaskawa or your authorized service provider before opening the enclosure to avoid voiding coverage.
Rough cost: A pro service call runs about $300-800 for control board replacement or drive unit replacement.