Multi-brand
VFD / AC Drive Repair — ABB, Yaskawa, Danfoss, Mitsubishi, Eaton (up to 25 HP) — Mail-In
Component-level repair for AC drives up to 25 HP across major brands: ABB ACS series, Yaskawa V1000/A1000, Danfoss VLT, Mitsubishi FR, Eaton, Fuji, Hitachi, Delta. Free evaluation, typical repairs $300–$900.
Coverage: ABB ACS150/355/550 · Yaskawa V1000/A1000/GA · Danfoss VLT/FC · Mitsubishi FR · Eaton · Fuji · Hitachi · Delta — up to 25 HP
✓Fixed — or it's free
Unrepairable units are refunded; evaluations cost $0
✓24-month warranty
Every repair covered, parts and labor
✓3–5 business days bench time
Rush (1–2 day) and emergency service available
✓Program preserved
Your application and settings stay in the unit
Symptoms this repair fixes
- ✓Overcurrent / ground fault trips
- ✓Dead drive
- ✓DC bus faults
- ✓Display/keypad failures
- ✓Fan failures and overtemp trips
Honest limits
- ✕Drives over 25 HP at launch
- ✕Motor-side faults
What you get
- ▸Free evaluation and firm quote
- ▸IGBT / rectifier / bus-capacitor replacement
- ▸Precharge and control repair
- ▸Powered test with motor load appropriate to frame
- ▸24-month warranty
Typical families
Part-number pages for this service
How VFD Repair (ABB, Yaskawa, Danfoss & More) units actually fail
Most units we receive fail in one of a handful of well-understood ways. Here is what each fault looks like from the machine, what is happening electronically, and what we do about it at the bench.
Output stage failure
- What you see
- Overcurrent or ground-fault trips, or a drive that faults immediately on start.
- Why it happens
- Output power device failure, usually precipitated by motor or cable insulation breakdown downstream of the drive.
- What we do
- The output stage is tested cold and repaired, gate drive verified, and drive output proven under run test.
Bus capacitor aging
- What you see
- Undervoltage or bus faults, or trips only under acceleration or load.
- Why it happens
- Electrolytic capacitor degradation with service hours and temperature, accelerated in hot panels and by long unpowered storage.
- What we do
- Bus capacitors are assessed and replaced and stability verified under load.
Pre-charge and control power faults
- What you see
- Instant trip on power-up, or undervoltage as soon as load is applied.
- Why it happens
- Failure of the inrush limiting circuit or the control power supply — commonly mistaken for a far more serious power-stage fault.
- What we do
- The pre-charge path and control supply are tested and repaired, and correct power-up verified.
Cooling failure and overtemperature
- What you see
- Overtemperature faults after a period of running.
- Why it happens
- Fan failure and heatsink obstruction in dusty or hot installations.
- What we do
- Cooling is restored and thermal behaviour proven under load.
Because this service covers several manufacturers, the free evaluation matters more than usual: it establishes both what has failed and whether repair is genuinely the right answer for that specific drive. On small, current, inexpensive general-purpose drives, replacement is sometimes the better decision, and we will tell you that rather than sell you a repair.
What happens on the bench
The same sequence on every 5-stage repair, so nothing gets skipped because a fault looked obvious.
- 1
Discharge and inspection
The bus is discharged and verified at zero, then the drive is inspected for the physical evidence that dates a failure — vented capacitors, heat-darkened board, corrosion from a damp or chemically aggressive environment, and dust loading in the heatsink.
- 2
Power stage and rectifier test
The input rectifier and the output IGBT stage are tested cold for shorted or open devices. Ground-fault and overcurrent trips are traced to the specific failed device rather than treated as a single generic "output fault".
- 3
DC bus capacitor assessment
Bus capacitors are measured for capacitance and ESR. Drives that have sat unpowered in stores for years are a special case: the oxide layer in an electrolytic capacitor degrades without voltage, and a drive that has been on a shelf can fail immediately on first energisation.
- 4
Pre-charge and control power
The inrush limiting circuit and its bypass, plus the control-power supply, are checked. A drive that trips instantly on power-up or reports undervoltage under load frequently has a failed pre-charge resistor or bypass relay, which is a far smaller repair than the symptom suggests.
- 5
Repair, then run test
After board-level repair the drive is run and its output verified, with the thermal path cleaned and cooling restored, so it returns proven under power rather than merely powering up.
Check these before you ship
Some of these will tell you the unit is fine and the fault is elsewhere. We would rather you find that out now than pay to ship a good unit.
- □Test the motor and motor cable first. An insulation fault downstream is the most common reason a drive fails again shortly after being replaced.
- □Write down the exact fault code and whether it trips on power-up, on start, during acceleration, or only under load once warm — each points somewhere different.
- □Check the heatsink and fan. Overtemperature faults on a dust-packed drive in a hot panel are often a cleaning job, not a repair job.
- □Confirm all three input phases are present and balanced. Input phase loss both causes drive faults and shortens bus capacitor life.
- □If the drive has been in storage for years, say so — it changes how we approach the capacitor bank.
Repair or replace?
Drives sit in the middle of the repair-versus-replace decision, and we will tell you when replacement is the better call. Repair wins decisively when the drive is obsolete, when it is one of many identical units you intend to keep as a maintainable fleet, or when a replacement means re-engineering mounting, wiring or parameters. A current-generation general-purpose drive in a small frame size can be cheap enough new that repair is not worth it — and if that is your situation, we would rather say so during the free evaluation than sell you a repair.
Ship your unit to
USPS
Control Board Lab
PO Box 120241
Arlington, TX 76012
UPS / FedEx
Control Board Lab
1009 Oakwood Ln # 120241
Arlington, TX 76012
Write your RMA number on the outside of the box and include it on a note inside. Units over 50 lb (large VFDs, spindle drives, industrial PCs in enclosures) ship by freight — contact us before ordering and we will arrange dock-to-dock shipping.
Frequently asked questions
My drive brand isn't listed — can you still look at it?
Almost certainly, if it's 25 HP or under. Use the part-number search or the quote form with your model number and we'll confirm before you ship anything.
Start with a free evaluation
Ship it in, get a firm quote, approve before any work — pay nothing if it can't be repaired.
The Fixed-or-Free Guarantee: if we can't repair it, you don't pay for the repair.
Call (817) 799-7332 · 📱 Text us a photo of your unit · Email repairs@controlboardlab.com