FANUC Repair
FANUC controls run half the CNC machines in America, and the legacy Series 0/16/18/21 hardware is where third-party repair earns its keep — factory parts for those generations are scarce. We repair servo and spindle amplifiers, power supply modules, and A16B/A20B boards.
Independent repair — not FANUC-affiliated
FANUC repair services
FANUC
Free evaluationFANUC Servo Amplifier Repair
Alarm 8, 12, or a dead amp on a FANUC machine? Free bench evaluation, firm quote before any work — most repairs land between $650 and $1,500.
3–5 business days in lab · Free evaluation →
FANUC
Free evaluationFANUC Spindle Amplifier Repair
Spindle alarms stop the whole machine. Free evaluation and a firm quote — typical spindle amplifier repairs run $750–$1,800.
3–5 business days in lab · Free evaluation →
FANUC
Free evaluationFANUC Power Supply (PSM) Repair
When the PSM faults, every axis stops. Free evaluation; typical repairs $500–$1,200.
3–5 business days in lab · Free evaluation →
FANUC
Free evaluationFANUC Board Repair (A16B / A20B)
A16B / A20B boards from FANUC controls, power units, and I/O — free evaluation, typical repairs $300–$800.
3–5 business days in lab · Free evaluation →
Product families we service
Alpha & Alpha i servo amplifiers
A06B-6079 / 6096 / 6114 — IGBT, bus, and control failures
Beta i amplifiers
A06B-6117 / 6130 series
Spindle amplifiers (SPM)
A06B-6078 / 6088 / 6111 / 6121
Power supply modules (PSM)
A06B-6077 / 6087 / 6110 — the shared single point of failure
A16B / A20B boards
Control power, I/O, memory & interface PCBs
Categories: Servo Drives · CNC Electronics · Power Supplies
What fails on FANUC hardware
Across the FANUC equipment that reaches our bench, a handful of faults account for most of it. Electronics age in fairly predictable ways, which is exactly why board-level repair works.
FANUC Servo Amplifier Repair
Power module failure
What you see: Overcurrent alarm, a drive that trips the instant it is enabled, or visible damage inside the unit.
Why: The IGBT power stage fails short, usually because of a downstream fault — a shorted motor winding or a motor cable that has chafed through — rather than spontaneously. This is why the cable and motor must be checked before a repaired drive goes back on.
FANUC Spindle Amplifier Repair
Power stage failure
What you see: Overcurrent alarms, tripping on spindle acceleration, or a drive that faults as soon as it is enabled.
Why: Spindle drives handle high current during acceleration and braking, and the power devices fail under that duty — often precipitated by a motor or cable fault downstream.
FANUC Power Supply (PSM) Repair
Pre-charge circuit failure
What you see: The module will not bring the bus up, or alarms immediately on power-up.
Why: The soft-charge circuit that limits inrush while the bus capacitors charge — the resistor and its bypass contactor or relay — is a genuine wear item, and its failure stops the bus reaching working voltage.
FANUC Board Repair (A16B / A20B)
Supply rail and capacitor faults
What you see: Random alarms, resets that clear on a power cycle, or a control that becomes unreliable once warm.
Why: Aging capacitors on the board supply produce marginal rails. On a machine control this presents as exactly the intermittent, wandering faults that are hardest to place on the machine itself.
Before you ship a FANUC unit
- □Megger the motor and its cable before condemning the drive. A shorted winding or a cable chafed against the machine frame will destroy a replacement drive exactly as fast as it destroyed the first one.
- □Record the alarm code and what the machine was doing when it tripped — during acceleration, at speed, on a hard stop, or only when warm. That distinction separates a power-stage fault from a thermal or feedback fault.
- □Check whether the cooling fan still spins freely and whether the heatsink is clogged. If the only fault is a thermal trip, cleaning and a fan may fix it on your bench.
- □Confirm incoming line voltage and phase balance. Repeated drive failures on one axis are often a supply or wiring problem the drive is simply reporting.
- □Note your parameter set if you have it recorded. Drive parameters normally live in the CNC or the drive's protected storage and our physical repairs do not touch them, but a record is worth having.
Repair or replace?
Servo and spindle drives are where repair economics are most favourable: the hardware is expensive, frequently obsolete, and often tied to a specific machine and parameter set. New replacements for older platforms are commonly quoted at multi-week lead times when they are available at all, and a like-for-like replacement still has to be parameterised and commissioned against the machine. Because a drive failure usually stops the machine outright, the number that matters is rarely the invoice — it is how many production days pass before the axis turns again.
FANUC part numbers
Control Board Lab is an independent industrial electronics repair company. We are not affiliated with, endorsed by, or an authorized service center for Allen-Bradley®, Rockwell Automation®, Siemens®, FANUC®, Mitsubishi Electric®, Yaskawa®, ABB®, Schneider Electric®, Pro-face®, Omron®, or any other manufacturer named on this site. All trademarks belong to their respective owners and are used for identification only.
Machine down? Let's get it back up.
Start a repair online in two minutes, or send us the part number for a free technician review.
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