A FANUC A06B number identifies a drive-system unit — servo amplifiers, spindle amplifiers, power supply modules and motors — and the four digits after "A06B-" tell you the family: 6079 and 6096 are alpha-series servo modules, 6078 and 6088 are alpha spindle modules, 6077 and 6087 are alpha power supply modules, while 6114, 6111 and 6110 are their alpha i successors and 6130 belongs to the beta i generation. The suffix after the H encodes the size or axis count within the family. Nearly all of the alpha generation and everything before it is long out of FANUC production — which is exactly why being able to read the number matters: it tells you in five seconds whether the module on your dead machine is a stock item or an orphan.
If you maintain CNC machines, the A06B number on the amplifier nameplate is the single most information-dense string in the cabinet. This guide decodes it, maps the families we see most, flags what is discontinued, and lays out the realistic paths — repair, used market, or migration — for each.
How the numbering works
FANUC's catalog prefixes split the control hardware world cleanly:
- A06B- — drive-system units: servo amplifiers, spindle amplifiers, power supply modules, motors, and complete amplifier packages.
- A16B- / A20B- — printed circuit boards, whether inside a control, an amplifier, or a monitor. When a repair shop talks about "board repair," these prefixes are usually on the board silkscreen — our FANUC A16B/A20B board service lives at that level.
- A02B- — control units and their major assemblies.
Within A06B, the structure is A06B-XXXX-HYYY: the four-digit block is the product family and the H-suffix narrows to a specific rating, frame size, or axis count. Two examples off our own bench: A06B-6096-H106 is a single-axis alpha servo module in a particular current rating, while A06B-6079-H208 is a two-axis unit from the neighboring alpha servo family. You do not need FANUC's full tables to make practical use of this — recognizing the family block is enough to know what class of module you are holding and what era of machine it belongs to.
The families that matter, mapped
As of August 2026, these are the A06B families we see most on inbound repairs, with their generation and lifecycle status:
| Family block | What it is | Generation | Production status | Typical repair path |
|---|---|---|---|---|
| A06B-6066 | Servo amplifier | C-series (pre-alpha) | Long discontinued | Board-level repair; used units scarce |
| A06B-6079 | Servo amplifier module (SVM) | alpha | Discontinued | Repair, or used market with unknown hours |
| A06B-6096 | Servo amplifier module (SVM) | alpha | Discontinued | Repair; heavily represented on used market |
| A06B-6077 | Power supply module (PSM) | alpha | Discontinued | Repair — the whole rack depends on it |
| A06B-6087 | Power supply module (PSM), larger ratings | alpha | Discontinued | Repair |
| A06B-6078 / 6088 | Spindle amplifier module (SPM) | alpha | Discontinued | Repair |
| A06B-6114 | Servo module (SVM) | alpha i | Superseded by newer i generations | Repair or exchange |
| A06B-6111 | Spindle module (SPM) | alpha i | Superseded | Repair or exchange |
| A06B-6110 | Power supply module (PSM) | alpha i | Superseded | Repair or exchange |
| A06B-6130 | Servo amplifier | beta i | Newer; some ratings still supported | Repair or FANUC channel |
The pattern to internalize: the alpha generation and everything before it is orphaned hardware. FANUC's support model for legacy amplifiers runs through repair and exchange programs rather than new production, and the further back the family, the more the practical support burden shifts to board-level labs and the surplus market. The machines these modules run — mills, lathes and machining centers from the 1990s and 2000s — are frequently sound iron with decades left in the ways, which is precisely why a BLS-counted manufacturing workforce of roughly 12.8 million people still stands in front of so many of them, and why Census business data keeps counting machine shops among the most numerous manufacturing establishments in the country. Nobody scraps a good machine over one dead module.
What fails, by module type
Servo amplifier modules (SVM families — 6066, 6079, 6096, 6114). Overcurrent and IPM alarms, dead amplifiers, fuses that blow at power-on, and faults following a motor or cable short. The physics is the same as every drive: power semiconductors fail from years of thermal cycling, DC bus electrolytics dry out on the Arrhenius schedule — roughly half the life for every sustained 10°C rise, by the capacitor makers' own model — and gate-drive circuits follow the components around them. Before condemning any servo amplifier, isolate it from the motor: disconnect and megger the motor and cable per IEEE insulation-testing practice, exactly as our amplifier-or-motor guide walks through, because a shorted motor will destroy a freshly repaired output stage in one enable.
Spindle amplifier modules (SPM families — 6078, 6088, 6111). Spindle alarms under load, trips on acceleration, fan and overtemperature faults, dead drives. Same component classes, bigger energies; repairs run from $750 upward with a full recap.
Power supply modules (PSM families — 6077, 6087, 6110). The PSM rectifies incoming three-phase and feeds the shared DC bus that every servo and spindle module on the rack drinks from — which makes it the single point of failure for the whole axis group. One dead PSM presents as an entire machine's worth of dead amplifiers; the diagnosis discipline is the same "check the common supply before condemning the loads" logic we preach for dead PLC racks. Rectifier, precharge, bus capacitor and control-supply failures are the classic repairs, typically $500–$1,200.
"Reading the nameplate is half the trade on old FANUC iron. A06B-6079 versus 6114 tells me the generation, the interface, and roughly what the used market will want for it before I've opened the cabinet door. The guys who skip the number and go by what the module looks like order the wrong exchange unit about once a year."
— CNC service technician, 22 years, job-shop machine tools; name withheld by request
Your options when one dies
Board-level repair. For orphaned families this is usually the shortest path back to cutting chips: free evaluation, firm quote, then repair with new power components and a recap. Typical FANUC servo amplifier repairs run $650–$1,500; spindle amplifiers from $750; PSMs $500–$1,200. Standard turnaround is 3–5 business days in lab (rush $149 for 1–2 days, emergency $399 for a same/next-day attempt, capacity confirmed first), and completed repairs carry a 24-month warranty. Servo and spindle parameters live in the CNC control on FANUC systems, not in the amplifier, so a repaired module reinstalls without a reprogramming project in nearly every case — details on the servo drive repair service.
The used and exchange market. Real, liquid for the common families, and priced by scarcity: single-axis alpha SVMs commonly trade in the hundreds used or rebuilt, while scarcer two-axis units like the 6079-H208 have been reported around $1,200–1,500 refurbished on the used market. The structural problem is that a used module carries someone else's decades of thermal cycles — you are buying the same aged capacitors and semiconductors that just failed in yours. Used units make excellent shelf spares to cover the repair window; as the primary fix they are a coin flip with a short warranty.
Migration. Replacing the whole drive package with a current generation, or retrofitting the control entirely. It is the right eventual answer for a machine the plant intends to keep another twenty years — and it is a capital project with engineering, downtime and re-commissioning attached, not a Tuesday fix. The repair-versus-replace math applies with the usual conclusion: repair to get running, migrate on your own schedule if migration is truly in the plan. The downtime side of that math is not subtle — ABB's 2023 Value of Reliability survey of 3,215 plant respondents put unplanned downtime at an average of $125,000 per hour, and DOE research attributes close to 70% of manufacturing electricity to motor-driven systems, of which a CNC's servo and spindle axes are the working end.
Two housekeeping notes that pay off later. First, photograph every amplifier nameplate in the cabinet now, while the machine runs — the day a module dies, having the exact A06B and H-suffix on file turns a scavenger hunt into a part-number search in our parts index. Second, fold these modules into whatever maintenance program your plant runs: NFPA 70B, a standard since 2023, is pushing exactly this class of aging electronics toward documented condition-based maintenance, and OSHA's lockout/tagout regime — credited with preventing an estimated 120 fatalities and 50,000 injuries annually — is the non-negotiable first step of any cabinet work, because amplifier bus capacitors hold lethal charge well after the disconnect opens.
When to ship it
Ship the module when it faults with the motor megger-verified clean, when it is dead, or when the whole rack is down and the PSM is suspect. Send the module only — the request-quote form with the full A06B number and the alarm history gets you an RMA, and the free evaluation gives you a firm number before any work. If the machine is a production bottleneck, say so on the intake and use the rush tier; if you are not sure which module of a multi-module rack failed, describe what the CNC displays and which axes are affected, because the alarm pattern usually points at PSM versus SVM before anything is unbolted.
Frequently asked questions
What does a FANUC A06B part number mean?
A06B is FANUC's catalog prefix for drive-system units — servo amplifiers, spindle amplifiers, power supply modules and motors. The four digits after the prefix identify the product family (for example 6096 is an alpha-series servo module, 6111 an alpha i spindle module), and the H-suffix narrows to the specific rating, frame size or axis count.
How do I tell a servo amplifier from a spindle amplifier from a power supply module?
By the family block in the part number. In the alpha generation, 6066/6079/6096 are servo amplifier modules (SVM), 6078/6088 are spindle amplifier modules (SPM), and 6077/6087 are power supply modules (PSM); the alpha i generation uses 6114 (SVM), 6111 (SPM) and 6110 (PSM). The PSM feeds the shared DC bus that all the other modules run from.
Are FANUC alpha series amplifiers still made?
No — the alpha generation and everything before it is out of new production, and support for legacy amplifiers runs through repair and exchange channels rather than the distributor shelf. That is not a death sentence for the machine: board-level repair keeps orphaned modules in service, and the used market provides shelf spares.
Can a FANUC servo or spindle amplifier be repaired?
Yes — the classic failures are power semiconductors, DC bus capacitors, gate-drive and control-supply circuits, all standard board-level work. Typical repairs run $650–$1,500 for servo amplifiers, from $750 for spindle amplifiers, and $500–$1,200 for power supply modules, after a free evaluation and firm quote, with a 24-month warranty on completed repairs.
Will I lose parameters if my FANUC amplifier is repaired?
Almost never — on FANUC systems the servo and spindle parameters live in the CNC control, not the amplifier, so a repaired module reinstalls without a reprogramming project in nearly every case. Keep your control's parameter backup current anyway; it protects you against control-side failures no amplifier work can cause.
The whole servo rack is dead — which module do I suspect?
The power supply module. The PSM feeds the common DC bus for every servo and spindle module on the rack, so one failed PSM presents as a machine's worth of dead amplifiers. Check the shared supply before condemning the loads — the same discipline as any dead rack — and ship the PSM, not the whole rack, once the pattern confirms it.
Is a used FANUC amplifier a better deal than a repair?
As a shelf spare, a used unit is a reasonable hedge; as the primary fix, it is the same aged hardware that just failed in your cabinet — someone else's thermal cycles on the identical capacitors and semiconductors, usually behind a warranty measured in days. Repair replaces the wear components with new parts in your own module and carries a 24-month warranty.
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