Buying a used or refurbished servo drive? Read this before you pay
When a servo drive dies and the new-original lead time doesn't fit your downtime budget, the used and refurbished market starts looking tempting — sometimes 40–70% cheaper, sometimes "available today". Sometimes that's the right call. But servo drives are among the least forgiving components to buy second-hand: they combine power electronics, electrolytic capacitors with a shelf life, firmware, and wear-prone cooling fans. This checklist compiles the eight checks experienced maintenance buyers run before money changes hands.
Why servo drives are riskier second-hand than PLC modules
- Aged capacitors — DC-bus electrolytic capacitors degrade even in storage; a drive that powers on today can fail within months.
- Unknown duty history — a drive pulled from a 24/7 stamping line has lived a different life than one from a test bench.
- Cooling fans and relays — the first mechanical parts to fail, and the ones cosmetic photos never show.
- Encoder and firmware pairing — drives are tuned to specific motor encoders; a "compatible" unit may still need parameter upload or firmware matching.
The 8-point checklist
1. What exactly does "refurbished" mean to this seller?
The word has no industry standard. Insist on the definition in writing: full reconditioning with replaced capacitors and fans plus load testing is a different product from "powered on once in the warehouse". Ask which components were replaced and whether a test report exists.
2. What was tested — and at what load?
"Tested OK" ranges from a control-power check to a full-load run with a motor. For drives above a few kW, only a load test (or at minimum a no-load run with bus voltage verification) predicts real behavior. Ask for the test procedure in writing.
3. What warranty do you get, and from whom?
A 90-day shop warranty and a 12-month seller warranty are different risk levels. Check whether the warranty covers replacement or only repair, who pays return shipping internationally, and how the RMA process starts. See what a serious seller-level warranty covers in our 12-month warranty policy.
4. Is the seller transparent about their business model?
Reputable independent suppliers state clearly whether they sell new-original, refurbished, or used stock — and never mix conditions in one listing. A seller who won't put the condition in writing is telling you something.
5. Serial number and traceability
Ask for the serial number and, ideally, date-code photos before payment. Stolen, swapped, or mislabeled units are a real risk in popular drive families. Traceability also matters if your insurer or quality system requires it.
6. Memory backup and parameter loss
Drives with memory-backup batteries may arrive with dead batteries and lost parameters. If you don't have the original parameter file, a "working" drive can still take days to commission. Confirm battery condition and ask whether parameters can be restored.
7. Firmware version compatibility
For multi-axis or networked systems (PROFINET/EtherNet-IP based lines), firmware mismatches can break communication profiles. Confirm the firmware version and whether the seller can flash a specific one.
8. Total cost of the cheap option
Price + return shipping + your technician's re-commissioning time + the probability of a second failure. When the drive controls a critical axis, one failed "bargain" can cost more than the new-original part ever did.
When new-original is the smarter buy
The used market makes sense for non-critical axes, trials, or when a genuine new part is truly discontinued and unavailable. But for most modern drive families, new-original surplus stock still exists — it just isn't on the big marketplaces. We specialize in exactly that: SHLY-PLC supplies 100% new original drives and PLC components (never refurbished or used), each covered by our 12-month seller warranty and inspected before dispatch. If you're weighing a used unit against a new-original one, send us the part number — comparing a real new-original price and lead time against the used offer takes one email, and it sometimes wins.
Frequently asked questions
Is it ever fine to buy used servo drives?
Yes — for temporary rigs, non-critical axes, or rare drives with no new supply, a well-documented used unit from a transparent seller can be rational. The checklist above is how you price the risk.
How can I tell a relabeled counterfeit from a genuine drive?
Label fonts and layout, seal quality, serial number traceability, and weight are the first tells. Our guide to verifying genuine vs counterfeit industrial parts walks through the full inspection routine.
Do refurbished drives void machine insurance?
Some insurers and OEM service contracts require new-original parts on safety-relevant axes. Check your coverage before choosing second-hand.
- Electrolytic capacitor aging behavior in storage — manufacturer reliability notes (Nippon Chemi-Con, Nichicon).
- Industrial drive refurbishment practices — EU Automation, Radwell service documentation.
- Counterfeit industrial electronics trends — ERAI annual reports.