Key Technical Specifications
| Parameter | Specification |
|---|---|
| Series | YASKAWA VARISPEED VS-626M5 |
| Typical Model Format | CIMR-M5A / CIMR-M5N + voltage/size code |
| Power Range | 3.7 kW – 30 kW (5 – 40 HP) |
| Output Frequency | 0 – 400 Hz |
| Control Method | Vector control for asynchronous spindle motors |
| Communication | YENET1200 high-speed serial bus |
| Power Architecture | Separate converter + inverter; shared DC bus |
| Power Devices | Low-loss IGBT with DSP-based PWM |
| Spindle Functions | Speed/torque mode, orientation, continuous regeneration |
| Encoder Interface | Built-in motor encoder for closed-loop speed and orientation |
| Protection | Overcurrent, overvoltage, undervoltage, overload, overheat, ground fault |
| Mounting | Control-cabinet mounting, forced-air cooling |
| Safety Note | Wait 5 min after power-off before touching terminals (DC bus capacitors) |
Product Introduction
If you are still pulling a VS-626M5 out of a CNC cabinet, the machine is probably older than half your maintenance crew. That is not necessarily bad. These drives were built for real machining — rigid tapping, spindle orientation, fast speed changes, and continuous regeneration — not for sitting in a catalog.The VS-626M5 sits between a general-purpose VFD and a full servo spindle amplifier. It uses vector control, a separate converter/inverter architecture, YENET1200 communication, and DSP-assisted PWM to keep spindle response tight. The M5A versions are typically standalone spindle inverters, while M5N versions carry the YENET1200 interface for direct NC integration. The weak spot is never the IGBTs alone. It is aged DC bus capacitors, dried thermal paste, cracked terminal blocks, and missing parameter backups.
Quality SOP & Tech Pitfalls
The Lab Report (SOP)
- Visual and counterfeit check: confirm YASKAWA label, CIMR-M5 model code, rating plate, and cabinet fit.
- Capacitor and bus check: inspect DC bus capacitors for swelling, leakage, or venting.
- Power-up test: apply correct DC bus or converter supply and verify boot, fault codes, and fan operation.
- I/O and encoder check: verify encoder feedback, orientation signal, and digital I/O response.
- Communication check: confirm YENET1200 link to the NC unit if applicable.
- Electrical checks: measure input/output insulation, terminal tightness, and fan current with a Fluke 115 or equivalent.
- Parameter logging: record all spindle parameters before shipment.
- Anti-static and mechanical packing: seal with test summary and handling warning.
The Engineer’s Warning (Pitfalls)
- Do not treat M5A and M5N as identical. M5N units expect YENET1200 NC communication; M5A units rely more on analog/digital I/O. Swapping the wrong variant can leave the spindle dead even if the drive powers up.
- Parameter loss kills more machines than failed IGBTs. If the parameter set is gone, the spindle may run, but orientation, gear-range switching, and speed limits will be wrong.
- DC bus capacitors age even in storage. A “new old stock” VS-626M5 can still fail on first start if the capacitors have dried out.
- Wait the full 5 minutes after power-off. The DC bus holds lethal voltage. I have seen technicians get careless here. Do not be that technician.
Installation & Configuration Guide
1. Pre-Installation
- ⚠️ Lock out all AC supply and DC bus sources.
- ⚠️ Wait at least 5 minutes, then verify DC bus voltage is discharged.
- Photograph all labels, wiring, encoder cables, YENET1200 connectors, and parameter screens.
- Record the exact CIMR-M5 model code and software/parameter version.
2. Removal
- Label power, motor, encoder, YENET1200, and I/O wiring.
- Disconnect the DC bus links carefully if the converter and inverter are separate.
- Remove the drive without stressing adjacent terminals.
3. Installation
- Copy all parameters from the old unit before power-up. This prevents most startup failures.
- Verify the replacement matches the original voltage class, power rating, and M5A/M5N type.
- Seat power and control connectors firmly.
- Reconnect encoder feedback and YENET1200 communication exactly as before.
4. Power-On & Testing
- Apply power and check for immediate fault codes.
- Verify fan operation and DC bus voltage.
- Test jog, speed reference, orientation, and gear-range signals.
- Run a low-speed test, then a full-speed test under no load before returning to production.
- Monitor temperature, vibration, and fault history for at least one full shift.
Compatible Replacement Models
| Compatibility Tier | Model / Path | Notes |
|---|---|---|
| ✅ Drop-in Replacement | Same VS-626M5 CIMR-M5 model | Best choice if the exact model code and parameters match. Still verify capacitors and fans. |
| ⚠️ Software/Engineering Compatible | YASKAWA modern CNC spindle drive / Sigma spindle platform | Likely requires parameter migration, encoder verification, YENET/NC communication review, and cabinet changes. |
| ❌ Hardware Mod Required | Generic VFD or non-YASKAWA spindle drive | Not recommended for CNC spindle orientation, rigid tapping, or YENET1200 systems without full engineering redesign. |
Frequently Asked Questions (FAQ)
Q: Is VS-626M5 still available new from YASKAWA?
A: No. It has been obsolete for years. Most units on the market are surplus, refurbished, or tested used.Q: Can I replace any VS-626M5 with another VS-626M5?
A: Not blindly. You must match the CIMR-M5 code, voltage class, power rating, and M5A/M5N communication type. A 7.5 kW M5A will not simply replace a 15 kW M5N.Q: Why does the spindle run but not orient?
A: Usually missing parameters, wrong encoder wiring, or a failed encoder interface. The drive can spin without orientation, but the NC will fault during tool change or rigid tapping.Q: Can I power it from a standard 3-phase supply?
A: Many VS-626M5 configurations use a separate converter to create the DC bus. Check your cabinet wiring. Applying AC directly to an inverter-only unit can destroy it.Q: What is the most common field failure?
A: Aged DC bus capacitors, failed cooling fans, cracked terminal blocks, and lost parameter sets. The IGBTs often survive longer than the surrounding parts.Q: Should I upgrade or repair?
A: If the CNC controller is still serviceable and the machine has years left, a tested like-for-like replacement is usually fastest. If the NC itself is obsolete, plan a full spindle drive migration with engineering validation.
