How to identify a Fanuc servo amplifier part number

Almost every Fanuc drive, motor and power supply carries a printed specification plate with a number beginning A06B-. That number — not the friendly series name moulded into the plastic, and not the SVM/SPM designation printed on the front — is what Fanuc and the spares market actually order against.

The plate is usually on the side or top face of the amplifier, and repeats a short-form model line (for example a servo amplifier module or spindle amplifier module designation) alongside the A06B- specification and a serial number. Photograph the whole plate. A partial number transcribed from memory is the single most common cause of a wrong part arriving.

Fanuc control boards and PCBs use a different prefix family — A16B-, A20B- and A02B- are the ones you will meet most often on boards, backplanes and control units. If the number on your board starts with one of those rather than A06B-, you are looking at a board, not a drive.

A06B- numbers are structured as a prefix, a four-digit group identifying the product family, and a suffix group that encodes the variant. Read left to right: the A06B- prefix marks it as Fanuc drive-family hardware, the middle group tells you which family and frame it belongs to, and the trailing characters after the second hyphen distinguish current rating, axis count and options within that family.

The practical consequence is that two amplifiers can share everything up to the last hyphen and still not be interchangeable, because the suffix is where axis count and current rating live. Treat the full string as atomic. Never truncate it in an enquiry and never assume a 'close' suffix is equivalent.

Fanuc also revises hardware in place. A plate may carry a revision or edition marking near the specification number. Note it if it is legible — for some families a later revision supersedes an earlier one and is accepted as a replacement, while for others firmware or backplane differences mean it is not. Where we cannot confirm interchangeability from Fanuc's own documentation, we will say so on the quote rather than guess.

A servo amplifier is only half of a matched pair. The amplifier must suit the motor's continuous and peak current, the feedback type the motor carries (the encoder generation matters), and the command interface the CNC expects — analogue, serial, or a fibre-optic servo link, depending on the generation of the control.

So when you request a quote, send three things: the amplifier's A06B- number, the motor's A06B- number, and the CNC series (for example a Series 0, 16i/18i/21i, 0i or 30i control). With those three, a supplier can tell you whether a proposed replacement is a genuine drop-in, a drop-in that needs parameter changes, or a different generation that will need a matched motor as well.

If the amplifier failed, capture the alarm code the control displayed before you power everything down. Fanuc drive alarms narrow the fault to the amplifier, the motor, the feedback cable or the power supply module — and it is common for the amplifier to be a symptom rather than the cause.

Burnt, painted-over and coolant-etched plates are routine on machines past their first decade. If the specification number is gone, you can usually still recover an identification from the machine builder's electrical schematic, from the CNC's own diagnostic screens (which report connected drive and motor identities on serial-interface generations), or from the spare-parts list in the machine's manual.

Failing all of that, clear photographs of the unit — front face, both side faces, the connector layout and any surviving markings — are often enough for a supplier who handles these daily to narrow the family. Send them with your RFQ and say explicitly that the plate is illegible; it changes how the enquiry is worked.