Fanuc Servo Module A06B-6080-H307 A06B6080H307 A06B-6080-H307

Fanuc A06B-6080-H307 | Alpha Servo Amplifier Module — SVM3-20/20/40, 3-Axis Type B, 283–325V / 4.35kW, 5.9A / 5.9A / 12.5A

Overview

The Fanuc A06B-6080-H307 is a three-channel alpha servo amplifier module, designated SVM3-20/20/40, providing asymmetric current output across its three axis channels: the L and M channels each deliver 5.9A continuous output matched to αC6/2000-class motors, while the N channel delivers 12.5A continuous output for a heavier α22/2000-class motor. This asymmetric three-axis configuration is a practical machine design tool — it allows three axes of differing motor classes to be served by one module, without requiring either the expense of a higher-current module for all three channels or the cabinet complexity of separate single-axis modules for each.

The A06B-6080 series is the Type B interface counterpart to the A06B-6079 Type A series. Both series contain the same SVM model designations and identical electrical ratings, but communicate with the CNC through Type B PWM protocol rather than Type A.

The Type B interface is used with Series 0-MD, 0-MF, 15B, 16B, 18B, and 21B controls — the B-suffix generation of Fanuc's CNC controls that evolved in parallel with the Type A-equipped A-suffix controls.

Mechanically and electrically, the two series are interchangeable; the interface setting determines which is correct for a given machine.

In practice, the SVM3-20/20/40 configuration appears on machines where two axes share a similar motor class (two αC6-class axes — perhaps X and Y, or A and C rotary axes) while one heavier axis (Z-axis with gravity-assisted load, or a large rotary table) requires the α22-class N channel.

The single 90mm-wide module handles all three without expanding the drive rail footprint beyond what a simpler three-channel SVM3-20/20/20 would occupy.

Key Specifications

Asymmetric Three-Axis Architecture — 20/20/40 Current Configuration

The SVM3-20/20/40 current designation identifies the peak current class of each channel in Fanuc's internal numbering convention: "20" corresponds to the 5.9A continuous output class (driven by 50A-class IPM modules), and "40" corresponds to the 12.5A continuous output class (driven by larger IPM modules capable of the higher sustained and peak currents the N channel motor demands).

Three different IPM modules fit within the 90mm module width because each IPM's physical size scales with its current rating — the "20"-class IPMs for L and M are smaller than the "40"-class IPM for N, allowing all three to co-exist within the compact 90mm format.

The N-channel IPM's higher current capability is why the A06B-6080-H307 draws 4.35kW from the DC bus rather than the 3.7kW of the symmetric SVM3-20/20/20 (H304) — the additional 0.65kW reflects the higher sustained power demand of the α22 motor on the N channel.

Type B Interface — CNC Compatibility Context

The Type B PWM serial feedback protocol in the A06B-6080-H307 is the interface standard for Fanuc's B-series CNC controls.

Functionally identical to the position/velocity/current loop architecture of the Type A interface, Type B differs in the specific serial communication parameters and timing that the CNC uses to transmit axis commands and receive feedback.

A machine configured with Type B controls must use Type B SVM modules throughout its drive stack — mixing Type A modules in a Type B installation produces communication errors between the CNC and the affected module.

The A06B-6080-H307 is tested and certified on FANUC 0-C, 0-D, 16, 18, and 21 generation controls in the Type B interface configuration.

Its compatibility with this control generation places it in a large installed base of CNC machine tools built across the 1990s and early 2000s — machines that remain in active production and regularly require servo module replacement as original components age.

FAQ

Q1: What is the functional difference between the A06B-6080-H307 (Type B) and A06B-6079-H307 (Type A)?

Both are SVM3-20/20/40 three-axis modules with identical electrical ratings: 5.9A on L and M, 12.5A on N, 4.35kW input, 283–325V DC bus. The only difference is the CNC communication interface.

The A06B-6079-H307 (Type A) works with Series 0-C, 15A, 16A, 18A, 21A controls. The A06B-6080-H307 (Type B) works with Series 0-MD, 0-MF, 15B, 16B, 18B, 21B controls. Substituting one for the other without reconfiguring the CNC interface will produce communication alarms. Always confirm the machine's CNC type before ordering.

Q2: The N channel carries 12.5A — can it also run a smaller motor like the ones on L and M?

Yes. The N channel's 12.5A rating is the maximum continuous current it will supply; it does not force the motor to draw this current. If a smaller αC6-class motor (needing 5.9A) is connected to the N channel, the drive operates at approximately half of the N channel's capacity. Servo parameters must be set for the actual motor model on N.

There is no electrical harm in using a higher-rated output channel with a lower-rated motor. However, the opposite — connecting a 12.5A motor to the L or M 5.9A channel — would cause overcurrent alarms under full-load operation.

Q3: What CNC alarms identify which specific channel on the A06B-6080-H307 has failed?

The 7-segment LED on the module shows channel-specific alarm codes. Alarm 8 (HCL) indicates L-axis overcurrent; Alarm 9 (HCM) indicates M-axis overcurrent; Alarm A (HCN) indicates N-axis overcurrent.

The CNC's SV alarm number identifies the corresponding machine axis (X, Y, Z). Combined channel alarms (b, C, d, E) indicate multiple simultaneous faults.

The standard diagnostic sequence is to disconnect the suspect motor's U/V/W cables and test motor insulation to protective earth — acceptable insulation is several hundred megaohms or higher — before concluding the module requires replacement.

Q4: How is the A06B-6080-H307 powered within the alpha amplifier system?

The H307 draws its 4.35kW operating power from the alpha PSM's shared DC bus, the same bus that powers all SVM and SPM modules in the stack. The PSM must supply the combined peak demand of all connected modules simultaneously.

For a machine with one SVM3-20/20/40 (4.35kW) and an SPM-11 spindle (17.5kW), the PSM must sustain at least 21.85kW — a PSM-26 (A06B-6087-H126) is a typical selection for this configuration.

The H307 has no internal power supply; it cannot operate without a connected and functioning PSM.

Q5: What is the repair approach for the A06B-6080-H307 when it fails?

The most practical path for most users is exchange: supply the failed module to a Fanuc service specialist, who provides a tested and warranted refurbished unit.

Component-level repair is available — transistor IPM modules, fuses, cooling fans, and absolute encoder battery packs are available as service parts. 

The wiring board and control card are not sold separately by Fanuc, but specialist repair facilities stock them.

All repaired H307 units should be tested on actual Fanuc 0-D or 16/18/21 Type B controls with appropriate alpha motors across all three channels before returning to service, verifying correct operation at rated current on each channel independently.